HullScant is the Wolfson Unit's Hull Scantlings program. It is used to evaluate the scantlings for motor and sailing vessels under 24 metres.

The program calculates the actual scantling structural properties of a vessel and can compare this with the requirements set out in the latest ISO standard 12215, Part 5 (2019) which deals with pressures and scantling equations for fibre reinforced plastic, metal and wood monohull boats.

The HullScant software is specifically designed for all builders and designers conducting a scantling assessment and will greatly simplify the process of design category assessment for pleasure craft under the Recreational Craft Directive.


A demonstration version of the software can be downloaded from our software area here.

HullScant Release 2 to ISO 12215-5(2019)

Answers beginning with R1 are relevant to HullScant R1 and the 'old' ISO standard 12215-5:2008/AMD 1:2014 ONLY. Answers beginning with R2 are relevant to HullScant R2 and the current ISO standard 12215-5:2019 ONLY . A number of answers are relevant to both Hullscant R1 and Hullscant R2




1. HullScant and the ISO 12215 standard

1.1 Can you please list the differences between Hullscant R1 and Hullscant R2

At the most basic level, Hullscant R2 assesses against ISO12215-5:2019 whereas Hullscant R1 assesses against 12215-5:2008 (inc A1 2014). The differences between the standards are significant, hence it isn't really possible to list the individual changes to the standard. In addition to the change to the standard, Hullscant R2 has a significantly changed user interface and increased geometry import functionality (IGES files of hullform and individual structural components can be read in), and a number of structure inputs (eg local deck height, panel height above DWL) are automatically calculated by the program. 


1.2 As HullScant is based on the ISO standard and the ‘design categories’ I presume that the pressures it calculates are based on the maximum wave heights for those categories.  Does this mean that if I enter a speed of 25 knots for Category B the pressures are based on 4m waves at that speed, or does it appreciate the vessel cannot be driven at that speed in that sea state ?

R1 > When writing HullScant the Wolfson Unit used the standard that is created by ISO working group 18, we do not write this standard. We understand there is an inherent consideration of reducing speed in waves - section 3.1 of the standard describes this –and there is consideration of this fact in the design pressure for certain types of vessel (e.g. see the Notes in section 8.1). If you would like a full and comprehensive technical answer to this question it would be best placed to the convener of the ISO working group. HullScant is an assessment of the provided particulars against the ISO 12215 standard, NOT an assessment of the vessels suitability for a specific environment.

R2 > There is an explicit listing for speed reduction of workboats in waves in Appendix J of the ISo 12215-5:2019 standard


1.3 Have you ever thought about producing a more general software without the ISO limits? That is, have you considered adding an option into HullScant to add design pressure directly – say a design load on deck or the load from a block? This could be called 'user load' with direct input of design pressure. The material and laminate stack build could be the same, but without the ISO limits while calculating the characteristics of a ply or stack, and instead the general theory can be used.

R1 > HullScant will never be able to go outside the ISO limits as this has never been validated and could lead to many user errors. In terms of your suggestions this may be difficult as there are intrinsic safety factors in the material properties etc. that are then accounted for in the ISO 12215 prediction of loading and pressure. One cannot work without the other. However, the user is able to obtain the stiffener and laminate strengths in the program without doing a full ISO calculation using the Results, Stiffer Properties or Results, Laminate properties menu items respectively. All in all, the software should not be considered to be a design tool; it checks conformity to the ISO standard, which in turn is a ‘sizing rule’. i.e. no part of the standard should be used in isolation.

R2 > While the above answer is still valid with respect to adherance to standards and intrinsic interaction of safety factors and design pressures, Hullscant R2 allows the user to specifiy their own design pressure in the Plating dialog. If this is enacted, the report clearly denotes that the results are not ISO compliant. It should also be said that the use of this feature and its implications are very much at the users discretion and responsibility.

1.4 What version of the ISO 12215 standard is used in the software ?

R1 > The program is in accordance with the April 2008 publication (2008-04-15) of 12215 part 5. We have released updates after every version change of the standard, free of charge to existing customers. The version of the standard used within a given version of HullScant is listed in the Report section, as well as the About screen. If you need to update your existing copy, please go to our Customer Download Area.

R2 >  The program is in accordance with the December 2023 ISO publication (2023-12-31) of 12215-5:2019 and some of the errata published by WG 18 up to and including 2023-12-31 . We have released updates after every version change of the standard, free of charge to existing customers. The version of the standard used within a given version of HullScant is listed in the Report section, as well as the About screen. If you need to update your existing copy, please go to our Customer Download Area.

1.5 What errata are incorporated in the software ?

Hullscant, as of 2024-02-22,  uses ISO on ERRATA items 4.6, 4.8 and 4.28, but incorporates ERRATA  items 4.14, 4.16 and 4.22.

In more depth, comparing the 2023-12-31 standard (ISO) versus the 2023-12-31 errata (ERRATA) , the differences that affect hullscant are –

ERRATA items :

4.6 Design area ERRATA has a limit of 2.5 b^2   . ISO has no limit on panel area .

4.8 ERRATA uses a limit of 3Lh^3   ISO has a limit of 5 Lwl^3

4.14  & 4.22 (the same point, but said in 2 different ways) .   Min core properties

  •    ERRATA : Sigma DCCO >= 0.004 P base
  •    ISO :         Sigma DCCO >= 0.008 P base
  •   ERRATA : Tau DCCO >= min (  max( 0.055Lh – 0.03 ,  0.3     ),     0.52    )
  •  ISO :       Tau DCCO >= min (  max( 0.07 Lwl – 0.12 ,  0.3     ),     0.58    )

4.16   ERRATA use a blend of K shb from 2008 and 2019 standards

4.28 ISO uses flexural stress, ERRATA uses tensile and compressive  

4.31   poisson ratio for CSM ; std say E/G -1   ERRATA say E/((2G-1) .

There are a few other ERRATA differences from ISO (eg Al material properties , table B1 & B2).

Commentry : 

4.16 – This was developed by industry professionals as their opinion was that ISO 2019 was overly penalising certain aspect ratios and curvatures.

4.14/4.22 – It is generally felt by the industry that the standard was overly conservative and effectively disallowed successful designs.

4.31: Both wrong : should be (E/2G) -1  by std theory , and that matches data in table C6 . Not actually used in anger in any formula inside Hullscant.

Hullscant, as of 2024-02-22,  uses ISO on ERRATA items 4.6, 4.8 and 4.28, but incorporates ERRATA  items 4.14, 4.16 and 4.22.

1.6 Is the program verified by a third party ?

R1 & R2 > The program has not gone through an official third party verification process and certification but R1 was endorsed by both the RYA (a Notified Body) and ISAF while R2 is used by an extensive number of notified bodies.

1.7 Does HullScant cover multihulls?

R1 > No, HullScant currently only covers monohulls, as per Part 5 of the ISO 12215 standard. Part 7 of the ISO 12215 standard is currently (June 2009) deleted, and hence there is no standard upon which to base the software.

R2 > The base module of HullScant only covers monohulls, but ISO 12215-7:2020 (multihulls) is due to be released as a additional module in the first half of 2024

1.8 Are the outboard motor forces  in Annex K incorporated into the panel scantlings?

R2 > No, they are purely informative and are not incorporated into the requirements / pass ratio in the main report. The origins of these formulae are in a VTT report (, section 7.12, page 105.

1.9 Can you assess a vessel as a workboat, as per Annex J?

R2 > Yes, just check the box in the 'Assessement' tabsheet and select the appropriate work boat type. The user can also select up to 12 different wave heights for speed reduction.

1.10 What happened to the 'user design pressures' checkbox on the Assessment tabsheet ? Its disappeared.

R2> This option is now on the 'Design Variations' dialog, which can be accessed via the button on the Assessment tabsheet. There were beginning to be too many options for the one control panel.

2. Geometry Import

2.1 IGES import of stiffeners is not working

R2>  Hullscant only reads curves when importing stiffeners, NOT surfaces. That is it reads the 'footprint' of the stiffener on the hull surface, extracting length and curvature. The stiffener library allows the user to create the stiffener shape. Stiffener spacing has to be specified by the user currently.

General notes about IGES import

Hullscant imports IGES from most source CAD packages with little issues. Occasionaly there are a few odd import issues, in which case please contact the Wolfson Unit. Packages that have been confirmed to import properly include Rhino, Solidworks, MaxSurf, and CATIA.  A few key points to remember are -

Individual surfaces are read as panels, and individual curves as stiffeners. That is, if you import the whole topside as one surface, it will be read as one (very large) panel. The user needs to split the surface into smaller surfaces, each one representing a panel as defined by the ISO standard.

Hullscant primarily reads NURBS surfaces, and prefers type 143 to 144; if data is not being transferred very well check what it is being exported as, and if the option is there, choose Type 143 trimmed NURBS surfaces.

Hullscant reads (and converts) according to the units listed in the IGES header. If the user has drawn the vessel in metres, but the CAD package is set to millimetres then the vessel will be scaled on import; check the unit setting in the CAD package !

  • hull definition import - surface & curves used
  • panel import - surface read only
  • stiffener inport - curves read only

Ensure you have the vessel in the correct orientation (X longitudinal, Y transverse, Z vertical). X =0 at aft end of waterline and +ve towards the bow. Z vertical upwards. The ISO standard has z=0 at DWL; Hullscant allows for a different vertical datum with the user specifying either draught or offset of DWl from the datum on the Assessment tab. 

It is also worth reading (if you haven't already) the 'General Order of Working' page in the Process Description section of the help files installed with the program ( 'About' pull down menu ->'Help'). There is also a simple 'getting started' guide available for download as well as a document discussing the different geometry requirements for multihulls , if that module is active and being used .

It is generally a good idea to import sets of panels (or stiffeners) together; for example save (and then import) all bottom panels in one IGES file, and all topside panels in one file. It is not essential to do this, but makes import, data management and tracking of issues much easier.

2.2Whats the best way of importing geometry, especially sheerline definition?

The ISO 12215-5 standard requires the height of the deck edge (ie the sheer line) and , where required, the chine line.for monohulls. ISO 12215-7 requires the height of a considerable more entities (float deck edge, keel line, wetdeck line, hull-wetdeck join etc etc).
To explain the concepts involved, a monohull shall be described first , after which the extensions required for multihulls will be described.
Monohull / main hull
The solution utilised in Hullscant is to define a number of transverse sections along the length of the vessel (ie stations in naval architecture nomenclature). There are 21 stations (stations 0-10 at half station gaps, each of which are defined by a set of points defining the shape of the hull. From the points that define these stations, specific ones are chosen to define the hull lines (keel line, sheer line etc) along the length of the vessel.
There are several approaches that can be used to define these station curves and hull lines; the easiest way is via importing IGES file(s).
  • The station curves can be defined by importing a set of IGES surfaces. Hullscant will calculate the extentd and then extract the curves and points at each station. If the IGES file also contains curves with specific names (see the relevant glossay {linkID=700}entries for these names), then the keelline, sheerline etc will be defined by these lines. If the IGES file does NOT have curves with these specific names, then Hullscant will attempt to define the keel and sheer from the imported shape. Which ever approach is used, the hull line (keel line etc) can be editted{linkID=*440} at a later point.
  • Import the keel line, sheerline etc one by one via the edit pull down menu. Import an IGES file consisting of points, lines and NURBS curves. surfaces will be ignored if this method of import is used.
  • As with method above, click on 'Add keel line' (or equivalent) in the Edit pull down menu but when asked where the data is to come from, click on 'By Hand'. Hullscant will create a best guess of the line, depending on what information is available (station curves, just hull dimensions etc etc). The user can then edit these values before accepting. As with the other methods, the curve can be editted at a later point.
It should be noted that there is not a current method for adding more points to a station curve other than adding an IGES file, hence using the 'by hand' approach has a minimal number of points defining the station. This is not a problem for the ISO standard calculations, but visually is limited and can be difficult if the points need to be extensively moved.
Multihulls have the need for addition curves, specifically -
wet deck profile
wet deck - hull join
float keel line
float sheerline
The demi-hull of a catamaran (or main hull of a trimaran) has the same hull line curves as a monohull, with the same method of import and editting.
There are also station curves needed for the wetdeck (and float for trimarans), from which the extra hull line curves are extracted These station curves are stored seperately from the hull station curves, and should be imported seperately, but the methods are the same).
Wetdeck stations are at the same X locations as the hull stations.
Float stations are at X locations determined by the floats extents, following the same logic as the hull (ie 21 stations, equally spaced).
While the hull (and float) keel and sheer are required at all 21 stations (indeed, the station positions are defined by the hull definition), there is not a requirement to have a wet deck station curve at each of the stations. If a wetdeck profile is present at a station where there is no wetdeck in reality, then it can be removed. In the 'edit wetdeck profile' dialog ( on the Hull Definition tabsheet either double click on the curve or vie the pull down Edit menu) , right click to get the pop up menu. The 'Remove wetdeck here' option should be visible. Wetdeck can be added / extended by a similar approach (ie pop up menu in 'edit wetdeck profile' dialog).
It is important to define the limits of the wetdeck correctly because this is used to determine if a side panel / stiffener is either clear or in way of the wetdeck .
2.2 How does the 'define floatation by draft' checkbox work?

ISO  references all heights with respect to the watering (Zq for a given panel etc)

Hullscant allows your vertical reference plane to be whatever you want (typically USK or DWL or mast step etc). The question then becomes what is the distance between the users reference plane and DWL; Hullscant allows that to be defined in 1 of 2 ways

  • The user defines the distance from their reference plane to the DWL
  • The user defines the draft of the vessel (and it already knows the vertical distance from the underside of keel to the reference plane as it has the station curves)

The choice of which of these approaches is used is set by the ‘Define floatation by draft’ check box-

  • if it is checked, then the user defines the vessels draft and Hullscant calculates the Zq = Z(panel in users ref frame) -  (ref plane -> USK -> DWL)
  • If it is unchecked then the user defines the distance of the ref frame from the DWL (be careful of direction !) . This then gives Zq = Z(panel in users ref frame) -  (ref plane -> DWL)

2.3 I want to change the vertical location of a panel, but its fixed

If you have imported the panel (or stiffener) as an IGES surface (or curve respectively) the default setting is to keep the shape as per the original IGES entity, with the height and area etc derived from this shape / perimeter definition. If the shape / size is to be kept , and you just want to move the panel vertically then click on the checkbox near the top of the panel dialog, listed as ‘Manually control areas and reference heights’. This will let the user change a number of parameters, but NOT the panels length, width or curvature. If you want to completely discard all links to the original IGES, then check the ‘manually control heights’ checkbox as above AND change the pull down options (listed as Link to IGES surface) to “No Link”. Be aware that if you reset the ‘link’ you can’t go back (ie it’s a one way process, as the surface information has been discarded), thus saving your work before doing so is a prudent action.


More information : There are 3 level's of linking to an IGES entity in hullscant : 1) a full link to the entity where the panel shape & location is recalculated from the IGES (which is saved alongside the hullscant file)  whenever it is loaded, 2) a storing of the IGES' discretisised shape , but NOT the underlying mathematical NURBS definition and 3) no link where the IGES shape is read and converted into a length, width and postion, and then all knowledge of the IGES surface is discarded. The default is level 2, where the IGES is converted to a discrete shape and that information is stored, allowing the user to move the shape around and manipulate it without storing the underlying mathematical defintion nor have to convert it to an equivalent panel each time.


2.4 I've imported a panel, but the shape does not look correct

Hullscant converts the true surface shape imported from the IGES file first into a 4 sided shape and then into an equivalent rectangular panel (ie length x breadth, with curvature Cl & Cb). The selection of the 'corners' of the 4 sided shape is determined by the change in direction as the perimeter of the surface is traced around. For some compex shapes Hullscant can chose poorly, so there is the option for the user to alter the corners. In the panel dialog, 'Orientation & weight' tabsheet, chick on the 'Edit corner location' button, and the resultant dialog will let the user move the corners -

Use the arrow buttons to shift the chosen corner around the edge of the IGES surface. The equivalent ISO panel is shown as a dotten red line,

3. Material properties

3.1 When I load a release 1 file into release 2, the material properties have changed

R2 > The 12215-5:2019 ISO standard has significantly different material properties for FRP's compared to the 2008/2014 standard. Note that a few metal properties (Al alloys in particular) have changed also. The 12215-5:2019 ISO standard does not have any core material properties listed, hence the data from 2008 has been used but these properties are known to be very conservative in comparison to manufacturers data sheets. In addition , 12215-5:2008/2014 used evaluation level A/B/C, which (in the case of level C) would lower material strength and modulus by a factor of 0.8. 12215-5:2019 does not use eveluation level, but does use Kbb & Kam (1 to 0.75 & 0.95 to 0.9 respectively) on the material strength (not modulus).

3.2 When I define material in the Material library, the program shows me the material properties. But in the data sheet of material I have much different values. Which is correct?

R1 > The values pre-defined in HullScant are those ‘approved’ and selected within the ISO 12215 standard. Actual material values will clearly vary according to manufacturing process, base materials, quality assurance etc. The ISO materials can be seen as the ‘average’ material, and there will be a great number of more specialised materials with higher strength or modulus, etc. There is also the underlying reason that the ISO values are relatively conservative, due to the requirement that they cover the materials produced by all manufacturers, as they can be used (via evaluation level c) without any material test data checks. You have the ability to enter your own materials into the database (and indeed, racing yacht designers do so regularly) by adding (‘Test Data Material’) to the materials database. Be aware though that there are separate rules and regulations covering a structure where you are using manufacturers test data properties rather than the default ISO values; The Wolfson Unit strongly advise reading Annex C of ISO 12215 part 5 (and any other associated Annex) before using test data values in your structural assessment.


3.3 In the boat particulars dialogue should I be using EL-b, measured fibre content by mass, or EL-c, ISO fibre content by mass? The latter gives a lower strength result.

R1 > If there is no explicit test data for the material then it should be EL-c. This is clearly described in Table C.1 of the ISO 12215-5 standard. There is a 0.8 factor on all mechanical properties calculated on the standard where there is not explicit actual measurement of the fibre content.

3.4 I’ve observed inequalities in the material property calculation between the ISO standard 12215-5 and the presented solutions in the HullScant application. The presented values are only 80% of the default values coming from the ISO standard. Why is this?

R1 > The default setting for the material properties are specified to be the “default data (Tables C.4 to C.7) with a multiplication factor of 0.8”, as per evaluation level EL-c , specified in Annex C, C.1.1,  General. Therefore you are correct to state that the values are 0.8 of the values specified. If you want to use EL-b (default data), select the required value in the boat particulars dialog. Be aware of the implications of the different evaluation levels and their requirement for quality assurance checks.

R2 > In the 12215-5:2019 standard the evaluation level has been removed, but a boat building factor  (Kbb) and assessment method factor (Kam) have been added, which range from 0.75-1.0 and 0.9 - 1.0 respectively, and can have a different combined value within the same structural assessment according to material type and manufacturing method.

3.5 HullScant does not seem to calculate carbon properly. If, for this boat, I insert a glass laminate with the same weight as one of the tested carbon laminates and check 'Calculate', the glass layup will pass but the carbon layup will fail - at the same weights. The carbon needs to be significantly beefier and heavier than the glass laminate in order to pass!

R1 & R2 > Check what orientation you have the carbon in. The material properties are determined in accordance with ISO (annex C, Table C.5 in particular). For example, double bias (DB) properties are very low in tensile and compressive strength. If for example you switched the outer layer (both inner and outer skins) to woven roving (300g/m) instead of DB (300) then the panels pass.

IF the NA is close-ish to the crown AND you have any 90 UD's (by which I mean UD running perpendicular to stiffener axis) AND you've entered this as an individual ply then HullScant will home in on its poor tensile failure strain of 0.45% or there abouts. It's a FPF (first ply failure) method.  If you have got this, try deleting these plies - if this is the problem then the M_offered will increase massively as the increase in limiting strain massively outweighs the minor loss in EI. This is why I model the inner skin/outer skin as two individual plies. My motto - never let HullScant see a 90 deg UD in tension!


3.6 Does EL c also take into account that the higher resin content inferred by the 0.8 factor would create a slightly thicker laminate?

R1 > The laminate thickness is the same as ISO data; only the material mechanical properties are altered (down to 0.8). This is an additional safety factor and the reduction in mechanical properties does not infer different resin content than the default values.


3.7 In the Material Library, when adding a GRP Multiple Laminate, what does “Multiplied or Crossplied Fabric” mean exactly? Is it a double axial 0/90° stitched fabric, a quadriaxial +/-45°/0/90° stitched fabric or still something else?

R1 > Multi or Crossplied fabric refers to bi-axial (0/90) fabric. If you need in the future to apply a double bias (+/-45) or quadriaxial fabric, you will need to add the material in the material library from: {Material Library => Add =>GRP Laminate} and then build your layup in the laminate library.


3.8 What is the difference between biaxial, double bias and multidirectional fabric? They are all unidirectional fibres that lay on top of each other in different angles and are stitched together. Am I mistaken?

R2> Double bias is +-45 degrees, Bi axial is +-90 degrees, as per the ISO standards naming convention (eg Table C 5) .  When adding materials into the library from the ISO database, the material name should reflect the fibre angle

R1> Double bias is +-45 degrees, Multidirectional (Crossplied) is +-90 degrees.

Note : You should not use DB or Quadraxial cloth in the "multiple laminate" because these have quite different properties from the more basic CSM, WR etc. where these are treated as a homogenous material with a thickness. Therefore you have to use laminate analysis for these.


3.8 In the Panel Results, what is the second column? Is it the minimum requested thickness or the minimal dry fibre weight as defined in 10.6.2 for FRP. The results don’t quite tally with what I expect them to be.

R1 > For FRP single skin panels HullScant calculates the equivalent required thickness from the dry fibre weight specified in ISO12215-5 Part 10.6.2 and examines this against the actual thickness. So HullScant does compare thickness against thickness. Check that you are not using a ‘laminate’ sandwich. You should be using a “Multiple GRP laminate” via the materials library (these (single skin & sandwich) are assessed in different ways


3.9 I would like to use Coremat type materials in the webs of some stiffeners to increase web stability. If I use “add>>core material” in the materials Library window, there is no option for this type of material. If I insert it as one of the options show or as a test data material there is no option that makes it work as a material that increases shear web stability. Do you have a workaround for this?

R2> Read the answer for R1 below (it has the background details and concepts), but in addition, the new standard allows flexural strength to be used (for single skin only, not sandwich structures), so the used does not have to make test material with the compressive/tensile strengths overwritten as per R1, but coremat does still need to be classed as a Laminated Ply (if it was classed as a core then it would be assessed as a sandwich ). The download at the end is a R2 file.


R1 >  Coremat thick is typically only half of total thickness of laminate and E value is much higher than real cores. This means treatment as a 'thin' sandwich (i.e. make as laminate in HullScant) is probably not correct. It is probably only ever used with CSM & WR which means normally the user would model panel as a multiple GRP laminate (i.e. a material). This uses flexural properties, not in plane. For example if you make up a multiple GRP material (see “6 x CSM MATERIAL” in the Materials dialog below) which gives a thickness compliance factor of 1.058. If the same 6 plies of CSM600 are modelled as a sandwich then it fails. This is because ISO defaults to in-plane properties for sandwich and UTS CSM < UFS. The problem is therefore how you get the laminate to use flexure properties, not in plane.

Define the Coremat as a material (‘Test Data’); It is probably best not to model COREMAT as a core material; use E glass instead, entering the relevant material properties (see screen grab below). Next add the other plies used (CSM, WR) as ‘Test Data’ as well, using flexural properties only the user can then build a laminate with Coremat in.

Finally, it might be worth doing a manual shear strength check at the neutral axis.


CSM, using ISO material properties                                                                                                          CSM, entered as ‘Test data’, and specifying flexural properties only                                   COREMAT as a ‘Test Data’ (note material type)


An example laminate





3.10 I am adding materials to the material library.  I am stuck as to how to add Soric flexible core.  I can’t add it as a core because none of the choices in the drop down menu are even close, and I have the same problem trying to add it as a reinforcement.  Do I add it as a “test data material”?

R1 > Entering the information as test data is the correct approach, but this isn't going to be that straightforward.......

If you treat it a sandwich (i.e. SORIC entered as a core in test data) HullScant will recognise it as a core and will employ thin sandwich theory as per ISO.  The core will have a zero E value and the program will do both a core shear strength and EI check in addition to BM check. This is wrong. The E value of the SORIC is much, much higher than a normal marine core AND these aren't really cores but 'bulkers' and are typically 2-4mm thick so thin sandwich approach is violated.

The best way to deal with this type of product is to treat it as a single skin (but using the laminate stack Annex H) - i.e. SORIC is entered as a laminate in test data. Without the magic word, 'core' HullScant will treat as any other ply and include the SORIC E value. BUT it won't however do a shear or EI check.

Recommendation:  Treat as single skin.  If it is just 2-4mm thick bulker the SF and stiffness are probably not going to be a problem.  If they are thought to be so then you will need to model it as a sandwich AS WELL or do a manual check. Finally, if entering as a core (as a 2nd check), make sure shear elongation (<35% or 35%) is correct for the material - work out USS/G from the type approval certificate.


3.11 In your choice of core material what is the difference between PVC I and PVC II? Both are listed as cross linked.

R1 > There are three broad classifications for rigid PVC compounds: Type I, Type II, and CPVC. Type II varies from Type I due to greater impact values, but lower chemical resistance. CPVC has greater high temperature resistance. You should match manufacturer’s data to the type set in HullScant. Typically most would be Type I.


3.12 I’ve used Quadraxial ply as a single skin, with the results giving a 0 required thickness and failing. When I looked closer at the results, quad (and UDWR) shows zero for flexural strength in the material properties. Why is this?

R1 > This data is derived from Table C.7. There is no ability to derive flexural strength from this table and members of the Working Group suggest that only actual test data should be used for flexural as it is very difficult to predict. If you convert this to a Laminate then you can get an answer out of HullScant (laminates use in plane strengths whereas single ply constructs use flexural). It is clear that HullScant is quite conservative when a single ply is used as a laminate. So two solutions... Use a laminate instead of single ply and increase the material to comply. Or get some test flexural data for the Quadraxial material and add this material as a “Test Data Material” in the Materials dialog using the other properties derived from ISO 12215-5.


4. Laminates

4.1 I'm getting a different minimum BM shown in the laminate dialog in Hullscant R2 compared to R1. I opened the R1 file, and made sure the material properties were kept the same, so why the different BM ?

For single skin laminates (ie no core), the 2019 standard allows the use of flexure strength ( C.2.3), whereas the 2008/2014 standard did not recommend it , hence Hullscant R1 always used compressive / tensile strength for FRP panels. Hullscant R2 uses flexural strength for single skin, & tensile / compressive strength for sandwich structures.

Most of the internal/ ISO FRP materials in Hullscant R1 did not have a flexural strength listed (follow on from point above), hence if importing and NOT updating material properties, one would need to add a flexural strength (there is a suggested formula in 2019, C.2.3).

By 2008 standard (and Hullscant R1), safety factor on material strength was 0.5  (with evaluation level possible also lowering strength AND modulus by 20%). By 2019 standard (Hullscant R2), safety factor is still 0.5 (table 17), but one also has Kbb  (1.0 for test materials, 0.75 for low) and Kam (0.95 for enhanced, 0.9 for simplified)

Hence even best comparison of  R1 v R2 Hullscant is going to have a 0.95 ratio on the design strength , which is the case with -

  • In Hullscant R1 set evaluation level as A, add a material (eg carbon WR 200g/m2), and make a laminate of 2 layers. In this case the min BM is listed as 2.46 with an EI of 243.07
  • Save, and load in Hullscant R2, being careful to keep material properties rather than updating them.
  • Open the material properties and set the flexural strength to the lower of compressive & tensile (which is what was being used in Hullscant R1). For carbon WR this is compressive, 56.7
  • Set Assessment method to enhanced (so Kam =0.95). Kbb will equal 1 as the material has been classified as test data.
  • Open the laminate, EI is 243.07 (ie same as in Hullscant R1) . Min BM is 2.34  (ie 0.95 of equivalent in Hullscant R1) . If assessment method is left as simplified, then the min BM is 2.22, 0.9 times the Hullscant R1 value.


4.2 When you create the material stack is the gel coat side at the top or bottom of the list, and does it make any difference anyway?

A laminate is created as if laying onto a female mould with the outer most ply first and inner most ply last. This applies to a schedule made using the laminate option. Using the multiple GRP material option it doesn’t matter (If you try the up/down buttons and check say flexural strength (which is the key property here) nothing changes). However, for best practise do it in the order of laying down (and the Wolfson Unit would tend to specify each individual ply rather than lump them together) is for audit purposes and so as not to confuse the builder in the unlikely event he needs to see the HullScant output.


4.3 I’ve got a CSM layup (which I was using as ‘single skin’ in Hullscant), but when I converted to using a laminate stack and added some WR, it starts to fail. What’s going on?

R1 > IN GENERAL: When you use the laminate option 12215-5 uses in-plane properties. The UTS of a CSM is about 68-80 MPa. When you use a MATERIAL stack (only available for CSM/WR/BX plies) it uses the Flexural strength - more like 130 MPa. Hence the different answers. The flexural strength is probably more correct for GRP single skin but data not so available for complex laminates hence LAMINATE option. Good for sandwich but for clever layups the user really should test the material properties. So if you have a WR/CSM/BX in roughly alternating plies or at least evenly distributed, use MATERIAL method and only use a laminate stack for cored layups

Back to the case in point: If you turn on stress ratios in results, and look at your hand lay bottom laminate, the problem is the WR ply in compression.  This is due to the low failure strain of WR compared with CSM.


4.4 I have created 2 different laminates, and used them alternatively for the same stiffener. However the stronger laminate is failing in HullScant, whereas the weaker one passes. What’s happening?

R1 > The stronger laminate (which fails according to HullScant)-

The weaker laminate -


HullScant/ISO-12215-5 is a first ply to fail method (FPF).  This means if a ply is introduced which has a much lower failure strain than any other of the plies, it will generally be that ply that triggers failure. This is what happens whenever a 90 degree UD is introduced as is the case for the panel with 195gsm 90 deg ply. When this is used in a stiffener as attached plating, the attached plate is in tension (12215 assumes built- in ends).  The tensile failure strain in the 90 deg ply is about 0.5% whereas it is nearly 2% in the other plies, so the 90 ply triggers failure.  

Sometimes it is possible to get away with this but if as in this case the weight of crown UD's moves the neutral axis well away from the plate then the problem is compounded.  Simply by deleting the two 90 plies from the laminate, the stiffener S1 one part becomes stronger (i.e. about the 14.3 kN.m given in the passing file). The same thing happens when you use aramid (unless you use a lot of it).


4.5 I’m considering using "Strongplank" material. What is the best way to model it in HullScant, particularly the "webs" in terms of cross linking the plies. Test data is a bit sparse. How can the cross linking of the skins that comes with Strongplank betaken into account?

R1 > The laminate analysis method assumes there is a bond between the skins and core. It would be necessary to input this as a material from test results to be sure. It should be analysed as a laminate for the purposes of the program.

If you have test data, and the shear properties are for the complete structure, then I would enter the properties as specified, and view the structure as one entity, i.e. skins included with the Strongplank 'core'.

It is understood this is a composite style strip-plank, i.e. used for hull, with the inner and outer faces glassed over with epoxy. Assuming that the radiused edges get filled with epoxy AND a top-notch secondary bond is produced, structurally we would have:

1. Outer and inner skin = horizontal flanges of Strongplank plus sheathing.

2. 'Core' material consisting of actual PVC core (assuming this has a decent density and it therefore structural) plus the vertical web.

It is suggested that a single pseudo-core having the actual thickness of the PVC be created but with properties derived as follows:

a) Calculate minimum strain from web and core (probably the GRP component)

b) Calculate the E value (or G value for shear) using:

G(effective) = (2 x tweb x Gweb + width PVC x G PVC)/(2 tweb + width PVC)

c) Calculate USS from G effective x min strain.

The actual laid up inner and outer skins should then be added to the laminate, but not the strong plank skins as they are already accounted for in the 'Strongplank' core.


4.6 I have a wooden yacht construction which is a combination of plank on frame, but with a double veneer of cold moulding over the top. Is this catered for in the program? I can see how to use normal plank on frame, and also full cold moulding, but not the combined.

R1 > First thing first – it is best to start reading all of Annex E!

There are two possible methods. The first is an Annex H laminate stack.  You need to set up two offered panels, one //, one #, corresponding to with or across the grain. This is a more conservative but more scientific method. It is very dependent in panel AR and it is suggested to use # to the grain.  The Wolfson Unit suggest you set up wood # to grain yourself to see what's going on. The alternative method is to treat the whole stack as a pseudo single material. Handle with care!  See the attached BST file for examples of both of these methods.



4.7 General hints & helpers in the use of HullScant

1. Avoid UD's for panels in HullScant - this is a first ply to failure method and not a laminate analysis program - always try to combine a multidirectional ply using the closest possible combination of WR, DB and QX

2. If UD's must be modelled (and this will mostly give lower strengths) then it is necessary to use the option to produce a 90 deg laminate (option available in the laminate toolbar - this automatically creates a second laminate at 90 degrees where UD0's become UD90's and vice versa.  QX/BX/WR/DB are unaffected) and within the second tab of the panel layup offer this new laminate in the long direction.

3. A much better approach is to use the material library option of defining test material and calculate the properties of the single ply in both directions using CLT (outside the scope of HullScant) but avoiding the ply by ply trap.  This avoids the problem - even a BX (same strain in two principal directions) always comes out better that a two ply layup of one UD0 and one UD90. E's are the same - strengths are different.

R1 > 4. Even better - use test data - not a lot of point going to the trouble of vacuum bagging only to use EL-C or even B really. 


5. Panels

5.1 What are the various abbreviations (e.g. Wos)?

R1 >

Wos = outer skin weight

Wis = inner skin weight

EI b is as per equation 42 of the standard, combining 2nd moment of area with modulus. The subscript b indicates in the shorter direction (see BML & BMb for corresponding bending moment values for long & short directions).


5.2 In the panel requirements dialog screen, what is meant by “The % panel area in bottom location specifies the percentage of an area of a side panel that extends into the bottom”?

R1 > The answer to your question is based on section 6.2 of the ISO 12215 - Part 5. The input you are required to enter into HullScant is the area of a side panel (for the hull) that extends to the bottom, in percentage term. For example, if your panel area is 100% above the waterline, then this value is 0% (i.e. a side panel). If, say 70% of the panel area is above the waterline and 30% of it is below, then the value to enter is 30% (i.e. a side panel that extends to the bottom of the hull). If the panel area is 100% below the waterline, then this is defined as a bottom panel in the dialog.


5.3 The K2 and K3 (aspect ratio) coefficients don’t appear to be correct comparing against table 5 in 12215-5:2008. With an aspect ratio of 1.67 the K2 & K3 values must lie between 0.468 / 0.476 and 0.025 / 0.026 respectively, but HullScant is providing much smaller values.

R1 > Check if you are using different material properties in the short direction as opposed to the long direction. Table 5 is for isotropic panels. For an orthotropic panel the function to Calculate K2 & K3 gets passed the effective aspect ratio based on the stiffness:

Effective aspect ratio, EAR:=(Length/spacing)*power(DS/DL,0.25), where DS:=short laminate EI, DL:=long laminate EI

This EAR is then directly used in the calculation of K2 & K3. Hence the different factors

This is as per Annex H.2.1.12, & table H.3


5.4 But ….Effective Aspect Ratio is only used in the calculation of alpha, beta b and beta l, and therefore in the calculation of Mdb (maximum design bending moment in the b direction, Nmm/mm), Mdl (maximum design bending moment in the l direction, Nmm/mm) and y/b (maximum relative deflection, mm/mm) for orthotropic panel calculations at Annex H (normative). It is never used in the calculation of K2 or K3, even if in the standard Table 5 is clearly indicated to be used for isotropic panels because orthotropic panels don't use it.

R1 > Table H.3, α and βb equations are curve fits to K2 and K3 as may be found in ABS guides.  To convert from α to K3 multiply by 12. To convert from βb to K2 multiply by 6.  Hence as high aspect ratio, α= 0.00237 or 0.028 as K3 and βb = 0.0833 or 0.5 as K2. This a minor difference, as in Table 5, the original Timoshenko coefficients were plotted on a more complicated basis. This is all true for AR or EAR. It was decided within HullScant to use α= K3/12 and βb= K2/6 in order to avoid minor differences when analysing either using Annex H or main body of the standard. The difference is trivial but might have caused some confusion with users. The equations in H.3 were checked against FE plate models to check their validity and also to develop βl.  There is no main body equation equivalent to βl so this is programmed as per Table H.3.  The FE plate models apply to especially orthotropic layups (e.g. plywood). DO NOT USE FOR COMPLEX ANGLE, NON-SYMMETRICAL LAYUPS - USE CLASSICAL LAMINATE THEORY (CLT). The presumption is that the stiffest direction is parallel to the short side as this is the logical way to layup a panel (having said that the equation will cope with minor (only minor) deviations from this presumption). As such by laying up the stiffest material in short direction, EAR > AR.  This makes sense as the panel is receiving less support from the long direction and so the panel more nearly corresponds to 'cylindrical bending' for which transverse strain is zero.


5.5 General hints & helper

R1 > The user doesn’t need to check the panel in both directions (short side and long side) in panel requirements if your laminates are CSM/WR. You only need to do this if you have a different offered material in that direction (e.g. 90 degrees to a unidirectional or a bias fabric).


6. Stiffeners

6.1 I'm getting a significantly different 'offered SF' in R2 when compared against R1 (eg 55% !) . I imported the R1 file into R2, and didn't change anything.

R2> See also 5.17 below for more detail but for background information the method of calculating shear stress and offered BM is different in R2 compared to R1. This in itself should only make a small difference (probably < 5% ). The underlying reason for big differences in offered SF (and BM at times) is the change to material properties according to the ISO approved values as well as the boat building factor (Kbb) and the assessment method factor (Kam). For example , take a multiply of CSM & WR. In R2 the material properties dialog shows the shear strength to be 42.91 N/mm2. In R1 it is 54.03 N/mm2  (including evaluation level C). For FRP, Kam is 0.95. If a boat building level of LOW is used (Kbb = 0.75) the shear strength in R2 then becomes 42.91 x 0.95 x 0.75 = 30.57 N/mm2 . That is, 56 % of that in R1. This then cascades thru into the offered shear force. 


6.2 The Results report shows a bending moment. Is that the maximum value that the stiffener can support?

R1 > Yes the ‘offered BM’ is the greatest BM the stiffener can support using the safety factors on materials as per the ISO standard.


6.3 Transverse and longitudinal stiffeners: do I have to specify a stiffener length as the gap between the crossing bonds ?

R1 > It depends on the stiffener and what it is expected to support. Usually transverse stiffeners are fully supporting the panels either side. Refer to Section 9.2. of ISO12215:5


6.4 Scantling bulkheads: do I have to input a bulkhead as a beam, divide it into longitudinal frames, and define it with the local height ?

R1 > Yes this is the method required. Refer to Section 9.2 of ISO12215:5


6.5 In the calculation result for stiffeners, is the “offered” values for the stiffeners base on exact values of section modulus or values from table in Annex G?

R1 > The section modulus for stiffeners is calculated from first principles, not interpolated or derived from the tables of Annex G.

R2 > As with R1, the section modulus is calculated from first principles


5.6 Is the effective plate width automatically adjusted if the stiffener spacing is less than that width?

R1 > If the stiffener is set up as a hybrid/laminate stiffener it will adjust the plating size accordingly and automatically. If the stiffener is set up as a complex stiffener then the plating size must be set in the stiffener builder. It will use this size to calculate mechanical properties.


6.7 Our current design has a large webframe without any longitudinal framing in the area of interest. Hence some of the stiffener is below the water line and some above. If I enter this as a bottom web, HullScant finds a design pressure of 20.5 kN/m2. If I calculate it as a combined bottom/side web, HullScant gives a design pressure of (only) 10.5 kN/m2.I also calculated it as a side web, and HullScant also gives 10.5 kN/m2.

In other words, it appears that HullScant assumes that most of the web is above the waterline, while in fact it is for more than 2/3 under the waterline.

R1 > What’s happened is the % of frame in the bottom zone has been set to zero (see highlighted input parameter in dialog box below).  So HullScant thinks it's all in the side shell zone and gives a 100% side shell pressure.  If you enter a figure of 80% in the bottom zone in the amended input, then Hullscant calculates according to part 5, 6.2.5. As the minimums govern, 10.5 kPa (side) and 20.5 kPa (bottom), HS calculates pressure as 0.2 x 10.5 + 0.8 x 20.5 = 18.5 kPa.


6.8 As I read the rule, if a bulkhead does not meet the structural requirements for a water tight bulkhead, it can be regarded as a stiffener. However, as I read it, you can only regard the bulkhead as a stiffener with a height of 7 time its thickness. In other words, it we have a bulkhead from 12mm plywood, it only counts as a stiffener 84mm high?

R1 > Not quite, no. A structural non-watertight bulkhead is handled under 7D (D = depth of hull in metres), as defined in Section 11.8.1 of the standard. The thickness of the bulkhead cannot be less than 7 times the depth of the hull in that area. See also the comments from a member of the working group to the question below


6.9 I didn’t see anything regarding the definition of non-watertight structural bulkheads, wood or sandwich (ref ISO12215-5 chap 11.8), in Hullscant. How are these accounted for?

R1 > Structure that is not classified as a bulkhead but provides structural support can be viewed as a stiffener (ISO 12215 part 6 is probably worth re-reading). Table 20 (sect 11.7.2) limits the height to thickness ratio (h/tw) to 10 for a flat bar plywood stiffener (thereby giving 120mm height for a 12mm ply structure).It is also worth reading section 11.8 of the standard.

And some words of wisdom from a member of the ISO 12215 working part – “a structural non-watertight bulkhead is handled under 7D (D = depth of hull in metres).  It's a semi-empirical equation, with some simple plate theory behind it, but not much. If you wish to analyse a ply or cored bulkhead as a stiffener, I believe that this should only be done in the case of cut-outs which produce a beam-like 'transverse frame', i.e. the span/depth > 5.  If this is the case then the dw/tw limits (to prevent shear buckling under in plane bending) become meaningful. I wouldn't try to analyse a deep ply bulkhead by just considering an artificial depth based on 12t or similar. An in-plane stress analysis of a deep bulkhead is not practical using simple equations.  The 7D seems from experience to give adequate racking stiffness so I'd leave it at that.  There have been various efforts to develop an equivalent stiffener but these predate the 7D.”


6.10 What is the best way of defining full height longitudinals and bulkheads i.e. those which are attached to both the hull and deck? At the moment I am treating them as a “T” type, but this poses the question of how much inner plate to use.  What is the usual method?

R1 > If the vessel is a small boat feature such as a RIB where the depth between bottom shell and deck is sufficiently small that the 'web' is attached to both deck and bottom so as to make an I-beam, then we then have an I-beam under deck pressure and bottom pressure.  There are a number of issues here, some 12215-5, some HullScant. The approach is to make a complex stiffener, i.e. manually enter the effective deck plating at 20 (t_i+t_o) deck + presumably cored web thickness and likewise for the bottom shell.  It is probably best to treat this as bottom stiffener as this gives the largest pressure. HullScant will then give you the compliance factors.

However, there are a few other things to consider. The first is web buckling.  Assuming a not untypical couple of plies either side of a H80, 20-30mm core, the ISO slenderness limits (based on 'hollow/PU' cores, albeit with a shear force compliance factor >>1) may need some additional investigation outside HullScant.

In the past, faced with these it is sometimes better to use an 'artificial' span since if you have a series of full-deck transverses and girders (i.e. egg-box style - see ISO-12215-6) you can't be sure what's supporting what. As the beam theory only really works for span/depth > 5, the user might also treat a floor web as an unstiffened WT bulkhead (even though it's not designed as such) since for a typical small boat head of 0.5-0.7m it ought to be able to survive no problem. Of course if this is a RIB or similar then the floor design point (built-in) is at the shallow ends under ISO - this might be a problem - one option might be to treat as simply supported and look for a minimum CF at the keel of 1.5 in bending from HS (assumption depends on deadrise).  However you still have to model the shallow depth at the deck extremes for shear and this could be a problem. A detailed analysis of this is beyond the scope of Hullscant and this FAQ; the user should speak to a structural engineer with a knowledge of the standard, relevant small craft structures and the requirements of the notify body.


6.11 For topside stiffeners, is there anywhere were the neutral axis for the top-hat-stiffener/hull-flange combination can be seen?

R1 > You should be getting this shown as a black dotted line in the laminate view window, as shown below.


6.12 When creating a stiffener can I insert pad layers (inner-skin reinforcements) separately form the hull laminate, or of width other than the hull plating effective width?

R1 > Yes, just insert layers in. Remember you will need to do this as a ‘complex’ laminate, rather than the standard off the shelf top hat etc.


6.13 Table 21 shows the value of Table 20 being multiplied by the square root of the actual BM over the BM design (hopefully less than unity). This then further increases the minimum thickness required for a given web or crown dimension which seems strange - is this correct or have I misunderstood the standard?

R1 > Ksm and Kas cannot be less than 1.0.  They are the ratio of the offered value to the required value.  So if you have more section modulus than required then KSM > 1 and so the applied compressive stress in the flange will be lower.  This means dividing by the 1% ultimate strain is making the flange unnecessarily stiff, hence the root Ksm factor.


6.14 Hullscant doesn’t appear to evaluate the slenderness ratios of stiffener web & flanges in much rigor. Also using a value of 35 for carbon laminates (Table 20) is a bit of an assumption since for basic GRP - covering the majority of craft - the value is 30 for webs and 21 for flange. What is the reasoning behind all this?

R1 > The crown slenderness ratio is loosely based on the Euler plate buckling equation which for an isotropic material is 3.62 E(tf/d)^2 where t = thickness and b = width of crown. The requirement is for this stress to be (roughly) twice the applied stress.  It is easier to write this in terms of strain so: d/tf = (3.62 /(2 x 0.5 ultimate strain))^0.5 (Note 0.5 is the allowable stress factor, and this is valid when the BM or SM compliance factor is 1.0000)

For GRP the ultimate strain in compression varies a lot between CSM and WR but using 1%, this equation would yield  (3.62 /(2*0.5 x 0.01))^0.5 = 19 (NOTE for all CSM using this logic, the factor would be more like 14). The figure of 21 is the ABS figure - it is in line with the above derivation (which was used for all the other materials) and 21 was kept to give agreement with ABS (ISO 12215 pt 5 tried to look a bit like ABS ORY).

Coming up with a slenderness for the web is even more difficult.  The web is actually under combined in plane bending and shear.  This requires a quadratic interaction equation which is too complex for use in a simple rule formula. The web limit is loosely based on shear stress only (and some comparisons with existing rules).

In addition, the methods assume a totally non-effective former. Even with a PU32 it is not certain if this behaves exactly the same as a genuine hollow pre-moulded/bogged down stiffener. For a 80 kg/m3 core, the slenderness ratios are probably meaningless. Also, many crowns have UD's (sometimes carbon UD300) with glass over bonding.  This is not only a mixture of two different materials but the orthotropic buckling equations are different from the isotropic ones.

No simple rule can do everything!

So because of the uncertainties, it was decided that the check should be a 'yellow box' warning only.  Many RIBS have very tall thin webs and it would be misleading if Hullscant was showing failures when these aren't happening in practice.

Finally, remember that ISO-12215-5 is one of a number of methods permitted under Recreational Craft Sectoral Group (RSG) guidelines.


6.15 Can I be sure the Offered Bending Stiffeness from the HullScant Report is correct ?

R1 > HullScant has been validated over a number of reference cases. Based on examplemotoryacht.bst (reference case which comes with the installation package), here is a detailed calculation for the "Deck Stiffener 1"/"Coachroof Stringer" attached to the "Coachroof Sandwich" laminate.
The calculation was performed based on ISO Standard 12215-5 chapter 11.
(In addition to the following, a worked example can also be found in Annex H which contains the full analysis for a Top Hat stiffener)



The difference of 0.5% is due to roundings and the true length of the webs used in HullScant software.


6.16 General hints & helpers

R1 > Effective width: The 20 (ti+to) (from LR SSC) really hits thin skinned cored panels with typically 20-30mm NOMEX 'former' L's. This is big reduction from the ABS ORY equivalent 't' .

If struggling to understand why the stiffener is failing

a), create it using the hybrid method - make a copy and then convert - this gives a nice graphic showing position of NA.  Makes it easy to see how highly loaded the plate v crown is and allows simply deletion/editing - it is also necessary for b) below.

b) If all else fails and only thing left is to pull NA closer to plate -  insert 'pad' of typically 200-300mm wide 3/4 plies of EUD0 under stiffener and over inner skin. 


6.17 Is the calculation method for EI, BM , SF etc for the offerered stiffener the same in R2 as R1?

R2 > As with R1, all properties are calculated from first principles. In general the same method is used except for the offered SF. In R1 the sum of the shear modulus area of the web multiplied by the strain at design stress determines the allowed shear stress and hence allowed shear force. In R2 the shear flow method, as presented in Annex H, is used for the enhanced method and the same approach as R1 for the simplifed method (where required) . Validation studies have shown the two methods to generally have the same answers , and usually within 5% of each other.


6.18 The stiffener report shows the offered bending moment (BM)  and shear force (SF) with and without the Kbb and Kam factors, but the ratio between the BM and SF changes from stiffener to stiffener, AND it is not always the same ratio for BM as for the SF. Whats going on ?

The Kbb factor ranges from 1.0 to 0.75 , depending upon type of material, layup (in case of FRP) and the build quality. The Kam factor ranges from 1.0 to 0.9, depending on material and assessment method. 

Example Stiffener A) Made using hand layup FRP, assessed by simplified method. The BM with factors is 0.855 of the value of the BM with Kam=1 & Kbb=1, as is the SF => Kam is 0.9  (simplified assessment of FRP) and Kbb is 0.95 (hand lay up, high quality). 0.9 *0.95 = 0.855

Example Stiiffener B) Made using FRP, stiffener  is built with resin infused former, attached plating has layers of hand layup; using simplified method. The BM ratio is 0.855 but the SF ratio is 0.9.  The shear force offered is being controlled by the web, which is resin infused FRP (Kam=0.9, Kbb=1.0 =>0.9), but the BM could either be the flange of the web OR the attached plating . In this case it is the attached plating (Kam=0.9, Kbb=0.95 => 0.855)

Example Stiffener C) Same setup as example stiffener B, and SF ratio is still 0.9, but BM ratio is 0.864 !  What is most likely here is that the critical layer for the BM has switched from the tension ply (attached plating, Kbb=0.95) to the compression ply (flange of stiffener, Kbb=1.0) , at which point the exact compressive and tensile strengths, and their ratio comes into play and a non-intuative ratio can occur.



Release notes: 

Release changes are cumulative.

Release Notes for Hullscant Version 23.02.24
  • FUNCTIONALITY- allowed option for multihull OR monohull to be base module
  • BUG FIX - on some displays the right hand edge of Internals dialog was being clipped
  • ISO STANDARD & ERRATA - rolled back on errata 2023-12-31 items 4.8 & 4.6 to be in line with republished ISO standard (2023-12-31). See report notes or website FAQ's for full details
  • FUNCTIONALITY - INTERNAL BETA MULTIHULL MODULE -  various changes and additions in response to beta testing
  • BUG FIX - 'walking area' function was not using the absolute of the angle to horizontal , so -45 was not being treated the same as +45. Fixed
  • FUNCTIONALITY - allow user to set the number of wave heights for speed reduction (work boat section)
    Release Notes for Hullscant Version 23.01.24
    • BUG FIX - Memory bug in formulation of modified K shb (version 15.01.24 only, 2023.12.31 errata) found and resolved
    Release Notes for Hullscant Version 15.01.24
      • ISO STANDARD ERRATA  new errata list (2023-12-31) published.
                      4.8 - Ksls limit of 5Lwl^3 removed in 2023-07-10 errata re-added, but at 3Lwl^3
                      4.16 - New formula for Kshb
      • BUG FIX - corrected possible bug in equation for Kl from errata, item 4.5 (never reported). Only affects very high Kdyn (> 7.0)
      • FUNCTIONALITY - Moved all 'show the following' checkboxes on to a separate dialog as it was getting too crowded. Added more options.
      • FUNCTIONALITY - clarified wording and delete/edit options for hull lines and stn curves
      • FUNCTIONALITY - added option for viewing geometry import documents  directly from Hullscant
      • FUNCTIONALITY - reporting greater number of coefficients used to determine design pressure
      • FUNCTIONALITY - INTERNAL BETA MULTIHULL MODULE - various changes and additions( wetdeck defn data structure, file write, beta testing issues)
      Release Notes for Hullscant Version 12.12.23
      • FUNCTIONALITY - added delete options for sheerline, keeline etc
      • BUG FIX - ensured pull down menu commands were enabled correctly when hulllines/sheerline etc were added/deleted
      • FUNCTIONALITY - INTERNAL BETA RUDDER MODULE - various changes and additions in response to beta testing
      • FUNCTIONALITY - INTERNAL BETA MULTIHULL MODULE - various changes and additions( wetdeck defn data structure, file write, beta testing issues)
      • BUG FIX - if stiffener requirements were calculated, then the order re-sorted (eg by position) the resulting offered shear force was different for a few specific cases, This was due to a memory bug (not all machines or installed versions would show it)
      • CLARIFICATION - Added note to the effect that web slenderness ratio for top hats is h/(tw/2), where tw is total web laminate thickness (see Table A12 of 12215-5) . No change to results or calculations
        Release Notes for Hullscant Version 27.10.23
        • BUG FIX - wooden stiffeners - if KE 0 90 = 0 (ie floating), SMo was equal to zero (SM of plating as tp=0). Fixed to use SM of lower edge of wooden web.
        • BUG FIX - If using 'complex' stiffener to build a metal floating stiffener, the tensile design stress was not always being found. fixed
        • FUNCTIONALITY - Follow on from item 4.8 of 10.07.2023 errata list, making Ksl > 1 for all sailing vessels, have added option to set speed for sailing vessels (to give Kdyn->Kl). Only of concern for high speed SY
        • BUG FIX - if plating curvature is a -ve number, the Kc factor was incorrect. Now using abs(curvature) in equations
        • FUNCTIONALITY - can not export ALL tabs of HTML report in one command
          Release Notes for Hullscant Version 11.10.23
          • FUNCTIONALITY - Added in-planer & shear modulus onto 'laminate properties' report
          • ISO STANDARD ERRATA - new errata list (2023-07-10) published. Changes to code, biggest relating to core shear strength (item  4.14)
                        Changes in Hullscant due to items 4.5, 4.8, 4.10, 4.12, 4.14, 4.18, 4.21, and 4.30
                        Note item 4.11 has not been enacted as it is listed as "could" and "to be discussed"
                        Note item 4.31 has not been enacted as it is preliminary
          • BUG FIX - Had erroneously been using Mldc, not Mlc in Outboard motor calculations
          • BUG FIX - when inputting chine line by hand, the sheerline could be automatically reset at the same time. fixed
          Release Notes for Hullscant Version 02.08.23
          • BUG FIX - design varients were not reported correctly due to base pressures not being updated (bug introduced in 05-04-23 version)
          • FUNCTIONALITY - RUDDER MODULE (BETA) - various changes and additions in response to beta testing
          • FUNCTIONALITY - MULTIHULL MODULE (BETA) various changes and additions( file read/write, GUI and pressure calc code)
          • BUG FIX - default thickness for materials was not editable after initial specification. Fixed, and removed material name query for Test FRP's
          • FUNCTIONALITY - report section details pull down now only shows sections chosen
          • FUNCTIONALITY - moved Z_sdt, Z_wdt functions from TStructure to TBoat class
          • FUNCTIONALITY - updated HASP dongle drivers
          • BUG FIX - Help file notes had not been updated with respect to Ad limit in Table 9. No change to code or calculations.
          • BUG FIX - Strain rates for wood materials were not always being calculated , causing simplified composite panels to have zero strength and infinite required thickness
          • BUG FIX - web slenderness for certain wooden stiffeners was not being set, giving a zero requirement
          • FUNCTIONALITY - added a few checks & warnings to highlight zero strain values when calculating laminate stress
          Release Notes for Hullscant Version 15.05.23
          • BUG FIX - Convert hybrid stiffener->complex for top hat stiffeners, if Bc & Bb were different, the result was the average, but this gave the wrong Bb which resulted in wrong effective plate width. Reset to be Bb only
          • FUNCTIONALITY - Included ability to add a void into complex stiffeners, in order to model top hats with no former
          • BUG FIX - removed some inconsistencies in setting and use of h , tw  & slenderness ratios for top hat and L stiffeners, mostly for 'stock' stiffeners
          • FUNCTIONALITY - clarified wall thickness specification for stock top hat stiffener
          • FUNCTIONALITY - clarified and improved visualisation of bonding layers in complex laminates
          • FUNCTIONALITY - added bonding width option for flat bar, L & T in hybrid stiffeners
          • FUNCTIONALITY - added listing of bonding width in stiffener report
          • FUNCTIONALITY - Fixed/forced stiffener 'attachment' to match that of the library stiffener chosen
          Release Notes for Hullscant Version 05.04.23
            FUNCTIONALITY - added option for showing structural element names in Hull Definition viewing window
            • FUNCTIONALITY - added option for showing centroid of structural items in Hull Definition viewing window
            • FUNCTIONALITY - added ability to delete stiffeners or panels in Hull Definition viewing window (either via 'delete' key or pop up menu)
            • BUG FIX - When using 'User Design Pressures' the requirement for Core compressive Strength was 0 as this is dependent upon Base Pressure. Fixed to allow user base pressures OR use ISO values.
            • FUNCTIONALITY - added stiffener weight per metre length in 'Stiffener' report
            • FUNCTIONALITY - addded cut, copy & paste (above & below) options (inc CTRL X, C, V & B shortcuts) in laminate build dialog
            Release Notes for Hullscant Version 08.03.23
            • BUG FIX - Clarified wording for alpha T &L for internals. Tweaked alpha calc for panels to avoid non zero's
            • BUG FIX - Alternative design cases were still being reported when 'user design pressures' were used. fixed.
            • FUNCTIONALITY - Moved outboard motor controls onto seperate dialog, allowing more space for multihull parameters
            • FUNCTIONALITY - MULTIHULL MODULE Added various GUI for multihulls & more multihull pressure defining functions/procedures
            • BUG FIX - memory bug in edit keel/chine/sheer line edit dialog identified and fixed (never reported).
            • BUG FIX - memory bug in IGES 110 occured if importing only 110 type curves as reference data.
            • FUNCTIONALITY - added more checks and autocreate options if creating keel / sheer line by hand

            Release Notes for Hullscant Version 20.02.23

            • FUNCTIONALITY - Added multihull functions, design pressures and ability to swap between mono <->multi in data structure
            • BUG FIX - reinstated alpha T & L edit boxes for deck (were only showing for superstructure), in both panel & stiffener dialogs
            • FUNCTIONALITY - Rationalised alpha T & L derivation for stiffeners to match those for panels

            Release Notes for Hullscant Version 16.02.23

              • BUG FIX - Which side of NA a stiffener's ply was located was wrong for a specific set of plys close to NA when finding highest strain ply. Stiffener strength table in results not affected. fixed
              • FUNCTIONALITY - Streamlined warning for core shear strength (each core only listed once) and clarified text of warning
              • FUNCTIONALITY - Added additional checks during file load in case of IGES link corruption
              • FUNCTIONALITY - Added speed warning in 'design variation' dialog
              • FUNCTIONALITY - Added plot for reduced speed in a seaway (Annex J, heavy duty workboats)
              • FUNCTIONALITY - Added additional text for methodology of workboats
              • FUNCTIONALITY - Added background data structure elements required for multihulls

                Release Notes for Hullscant Version 03.02.23

                  • BUG FIX - removed indexing error when loading a linked IGES file (not specifically reported, but possible source of bug report)
                  • BUG FIX - removed a repeatition of 'Stiffener' assessment method in foot of report
                  • FUNCTIONALITY - clarifed when a superstructure panel is deemed to be within a walking area (defined via 3.11 of 12215-5:2019) via radiogroup
                  • FUNCTIONALITY - tidied & streamlined superstructure panel orientation (to horizontal) code & editting
                  • ISO STANDARD CLARIFICATION - Design area limit of 2.5b^2 (item 4.4 , errata 2021-12-06) to be applied to BOTH planing and displacement. Neglectfirst line of errata ("This topic shall be considered separately for planning and displacement craft, in order to set 2 diffrerent Ar limit for panels")
                  • BUG FIX - Kar limit of 1 applied to bottom deck & side panels (planing), not just bottom panels (reversal of errata from member of working group)
                  • BUG FIX - write CSV was giving a column offset if panel/material etc name had a comma in it. fixed.
                  • FUNCTIONALITY - added Z keel & hull depth at structure location in results output (CSV, PDF & HTML)
                  • FUNCTIONALITY - increased efficiency during results calculate by reducing number of calls to USK function
                  • FUNCTIONALITY - added options for design variations (category, displacement etc), and altered GUI accordingly with additional dialog
                  • BUG FIX - visual only: 'Mass of fibre reinforment" label & box were shown(but not active) in material properties dialog for non FRP materials. Now hidden.

                    Release Notes for Hullscant Version 12.12.22

                    • BUG FIX - ensured required shear stress was > 0 ; req shear force (tension /compression sign) was making it -ve in a few cases
                    • BUG FIX - flange slenderness ratio for T & L's was not compensating for the width of the web
                    • FUNCTIONALITY - added further checks upon material properties, giving warnings if a 0 strength value is refered to.

                      Release Notes for Hullscant Version 19.10.22

                      • FUNCTIONALITY - Added check for wood (and metal) in a laminate when transposing by 90 deg
                      • BUG FIX - test data metal shear modulus was being overwritten by 12215:8-2009 G=E/(1+v) get around (set in May 2015) for lack of data in standard
                      • FUNCTIONALITY - Label for tensile strength for metals clarified as "Ultimate Tensile Strength", not just "Tensile Strength"
                      • FUNCTIONALITY - upgraded IGES library for varying discretisation of surfaces (should not affect hullscant)
                      • BUG FIX - possiblity of index error when creating a report when no materials in library removed (never reported)
                      • FUNCTIONALITY - if file access issues incurred when creating the HTML report, will try agin with location of BST file (Windows 11 can cause issues)
                      • BUG FIX - memory bug in discretisation  of IGES line (110) fixed (never reported)
                      • FUNCTIONALITY - improved formatting and increased robustness for rudder module reporting
                      • BUG FIX - stiffener dialog (but NOT the report) slenderness warnings were using some data from 12215:5-2008. both dialog and report now using only data from 12215:5:2019
                      • BUG FIX - in a number of cases Kas (slenderness attenuation factor) was being applied to flat bars, not just L bars, T bars & top hats.

                        Release Notes for Hullscant Version 04.08.22

                        • BUG FIX - rudder laminate indexing error when swapping materials in materials in library
                        • BUG FIX - Bb in complex stiffeners was including skin thickness.
                        • FUNCTIONALITY - clarified header in reports to be 'Be +Bb', not just 'Be'
                        • BUG FIX - Formating of logo in HTML report was omitted in some cases
                        • ISO STANDARD ERRATA / BUG FIX - UTS of welded Al alloy (5083 & 5059) corrected. Used errata 2021-12-06 data (12215:5-2019 , 12215:8-2009 & errata 2021-12-06 are all different)

                        Release Notes for Hullscant Version14.07.22

                        • BUG FIX -  Re wrote core design strength routine (panels) to avoid bulking core zero design strength
                        • FUNCTIONALITY - altered checks on materials used when delete material is called.
                        • BUG FIX / FUNCTIONALITY - Clarified and visually present what Bb (ie breadth at base) value is for complex stiffeners
                        • FUNCTIONALITY - Allowed used defined wave heights for heavy workboat reduced speed calculations

                          Release Notes for Hullscant Version 06.07.22

                          • BUG FIX - error in IGES file read for ARC (type 100) and LINE (type 110). Never reported.
                          • FUNCTIONALITY/BUG FIX - changed 'check for update' protocol due to website migration
                          • FUNCTIONALITY - added download button when checking for updates
                          • FUNCTIONALITY - Rudder module GUI changes

                          Release Notes for Hullscant Version 26.05.22

                            • BUG FIX - error in formulation of outboard load coefficient C ob
                            • BUG FIX - SAN core was mistaken listed as honeycomb when using ISO supplied data (text only, no numerical error)
                            • BUG FIX - there were a specific set of conditions where bulking cores gave a zero design strength.
                            • FUNCTIONALITY - Rudder module in full beta mode - covers types 1-V
                            • FUNCTIONALITY - Improved warnings on material properties (e.g. if material is in stiffener and has zero flexural strength, causing issues with slenderness ratios, warnings are raised)
                            • BUG FIX - IGES files with text strings > 160 characters origination from Solidworks were causing some import issues.
                            • FUNCTIONALITY - rudder module now using full R2 dongle code in release version
                            • BUG FIX - saving rudder as R1 file had an indexing error
                              Release Notes for Hullscant Version 27.04.22
                              • FUNCTIONALITY - Using a common WUMITA IGES library rather than project specific one (ie all IGES routines now shared with other software)
                              • FUNCTIONALITY - RUDDER MODULE continued debug via beta testing
                              • FUNCTIONALITY - added check on default material allocation and auto select if nothing there
                              • BUG FIX- possibility of issues when writing/reading rudder file version with mar-apr 22 versions
                              • BUG FIX - core material properties (when taken from ISO database) were initally editable when they shouldn't have been
                                Release Notes for Hullscant Version 21.04.22
                                • BUG FIX - Saving as R1 files, steel was being catagorised as wood. Never reported.
                                • FUNCTIONALITY - RUDDER MODULE continued debug via beta testing
                                • FUNCTIONALITY / BUG FIX - auto calc of panel dimensions for complex (eg high in-plane curvature) shaped panels improved; more accurate calculation of area, and area used to determine 'b' for all cases (as per 7.3)
                                • FUNCTIONALITY / BUG FIX - improved winding number algorithm to give better discreitsation of trimmed IGES surfaces
                                  Release Notes for Hullscant Version 06.04.22
                                  • FUNCTIONALITY - restructured 'add materials' process to allow for additional (rudder) materials, including option for welded/non welded on all relevant metals
                                  • FUNCTIONALITY - Where discrepencies in metal material properties exist (eg 12215-8:2009 Table A1 v 12215-5:2019) , the 2021-12-06 errata list has been taken in preference (corrected B1 in preference to correct B2 where differences lie iwithin this document)
                                  • BUG FIX - ISO material property metals could have strengths edited by a particular combination of editting; fixed to be read only
                                  • BUG FIX - some legacy rudder file structures were causing indexing errors on file write
                                  Release Notes for Hullscant Version 31.03.22
                                    • FUNCTIONALITY - all rudder dialogs added; not yet active as undergoing validation testing
                                    • FUNCTIONALITY - ability to save results in CSV format (as opposed to HTML or PDF)
                                    • FUNCTIONALITY - increased number of IGES curve types that can be converted to keel and sheer line (related to CATIA derived files)
                                    • BUG FIX - 12215-8:2009 removed bug (present in R1) relating to K flat calculation
                                    • BUG FIX - Approx backing plate width calc had indexing error for metals and homogenous attached plating (used in Stiffener report only)
                                    • BUG FIX - reporting of core shear strength in stiffeners (if requested) was not occuring if core was first material in library
                                    • BUG FIX - stiffener core shear strength was still being used in overall pass/fail logic when requested not to be
                                    • FUNCTIONALITY / BUG FIX - made formatting consistent between HTML combined tables and individual tables for stiffeners (there were some differences when including core shear strength)
                                    • FUNCTIONALITY - Added default E for mild steel as per note of table B.1
                                    • FUNCTIONALITY - Altered dongle check at program launch to reduce number of checks
                                    • FUNCTIONALITY / BUG FIX - Clarified warning about vessel being over the upper length limit (ie added comment about load line length)
                                    • FUNCTIONALITY / BUG FIX - Ensured same process/routines called for different approaches to materials library (ie via Materials tab v. Laminate dialog -> open materials library dialog)
                                    • BUG FIX/FUNCTIONALITY - ensured Test data FRP allow editting of manufacturing type (affecting Kbb ) AND material properties (different access to library had been allowing one or the other, not both)
                                    • BUG FIX - Some test data FRP materials were being classed as hand layup CSM and hence there was the possibility (never reported) of getting wrong Kbb. Query added for adding test FRP materials
                                      Release Notes for Hullscant Version 15.02.22
                                      • BUG FIX - simplified sandwich SM were at times using desing stress from opposite skin (ie inner for outer)
                                      • FUNCTIONALITY - Files now using new rudder data structure
                                      • BUG FIX - save R1 file was using wrong file version for rudder (should only have affected the 08.02.22 version)
                                      Release Notes for Hullscant Version 08.02.22
                                      • BUG FIX - core shear limit should only be applied to bottom and topside only , not other panels (as per ISO errata)
                                      • FUNCTIONALITY - added background dialogs and visual import for rudder module
                                      • FUNCTIONALITY - set stiffener core shear limit (Table A12 note referring to Table A7) as an option (default OFF)
                                      • BUG FIX - web buckling check was using design stress, not actual stress, for certain laminates
                                      • FUNCTIONALITY/ISO STANDARD ERRATA - Added notes to report concerning limits in Table A7 as per errata, and greater listing of methodology
                                      • FUNCTIONALITY - updated PDF report to mirror HTML report
                                      • FUNCTIONALITY/BUG FIX/CODE CHANGE -  Changed from whole laminate strain to web laminate strain for web skin buckling calculations
                                      • FUNCTIONALITY - Refined laminate strength calcs for core effective in bending
                                      • FUNCTIONALITY - Added laminate design strength to Laminate report
                                        Release Notes for Hullscant Version 26.01.22
                                        • BUG FIX - ply stress ratio tables for enhanced single skin laminates were at times using compressive/tensile strength, not flexture as per main analysis
                                        • ISO STANDARD ERRATA / BUG FIX - core compressive strength check changed to bottom & topside panel only, not deck, bulkhead or superstructure nor any stiffener
                                        • FUNCTIONALITY - tidied up separate table presentation for stiffeners

                                        Release Notes for Hullscant Version 20.01.22

                                        • BUG FIX - required core shear was listed wrongly in HTML report. Offered, ratios and pass/fail were correct.
                                        • BUG FIX - required core compressive strength equation was incorrect
                                        • FUNCTIONALITY / BUG FIX - reset work flow for sandwich webs to avoid possibility of laminate modulus being weighted by core.
                                        • FUNCTIONALITY - streamlined reporting of sandwich web of stiffener, clarifying core effectiveness (Table A 7) versus web shear buckling  (Table C2 of 12215:7-2020)
                                        • BUG FIX - deleting laminate could cause indexing error for library stiffener backing plating
                                        • FUNCTIONALITY - greater detail in notes & methodology for stiffener report

                                        Release Notes for Hullscant Version 13.01.22

                                          • BUG FIX - zero size IGES surfaces were causing indexing error on import. Added check when parins IGES surface, and remove panels <1mm by <1mm
                                          • BUG FIX - front page of PDF report - filename & date/time were in fixed font size. reset to match (scalable) font in rest of document
                                          • FUNCTIONALITY - added ability to alter PDF font sizing and spacing
                                          • BUG FIX - floating stiffeners were having the width of plys identified as plating reset to Be (as per stiffeners attached to plating)
                                          • FUNCTIONALITY - added Stiffener ply BM ratio's
                                          • FUNCTIONALITY - added Kam & Kbb coefficients, per layer in laminate schedules and per structural item elsewhere.
                                          • BUG_FIX - material property results for material stiffeners - possibility of indexing error removed (never reported)
                                          • BUG_FIX - sandwich stiffeners , if assessed by simplified method, were sometimes using weighted modulus, not the local layer modulus, when calculating SMi

                                          Release Notes for Hullscant Version 21.12.21

                                          • BUG FIX - PDF report was not showing required fibre weight results for simplified laminate panels
                                          • FUNCTIONALITY - Clarified which layers are counted in stiffener report
                                          • FUNCTIONALITY - Gave more options for interrogating IGES import to determine vessel size
                                          • FUNCTIONALITY - Allowed ability to alter width / height of multiple layers in laminates together

                                          Release Notes for Hullscant Version 07.12.21

                                          •  BUG FIX - flat bar stiffeners in report were beign formatted with red (ie fail) even when they passed
                                          • BUG FIX - stiffener report was not adding the backing plate; have reset to add effective width from 2008 standard. 2019 standard has variable width according to spacing, hence 'library' stiffener has undefined Be
                                          • ISO STANDARD ERRATA - Kam =1 for 'processed woods', rather than 0.9 or 0.95 (errata 2021-12-06 )
                                          • ISO STANDARD ERRATA - Footer of reports updated to indicate incorporation of all errata to 2021-12-06
                                          • FUNCTIONALITY - in stiffener report additional columns show BM & SF without Kam / Kbb for ease of comparison with 2008 standard
                                          Release Notes for Hullscant Version 23.11.21
                                            • BUG FIX - core compressive strength check was using design pressure, not base pressure. Have changed to bottom base pressure (either BS, BMP or BMD)
                                            • FUNCTIONALITY - added required core strengths to report (offered already there in material properties)
                                            • FUNCTIONALITY - added option to split results HTML tables into individual sections
                                            • BUG FIX - heavy duty work boat safety factor on materials was not being correctly applied to cores.
                                            • BUG FIX - Stiffener dialog , weight estimate, the word 'panel' was being used instead of 'stiffener'. No numerical changes
                                            • FUNCTIONALITY - Resolved some text in report being bold when it shouldn't have been
                                            • FUNCTIONALITY - if index of laminate/material is unrecognised, label of "Unidentified" is used instead of ignoring panel
                                            • FUNCTIONALITY - Added option to export / import stiffener library
                                            • FUNCTIONALITY - Added autosave function
                                            Release Notes for Hullscant Version 04.11.21
                                            • BUG FIX - stiffener specification of report was not resetting from warning colour back to clear. No change to numerics, just formatting
                                            • BUG FIX - 'complex' library stiffeners with 2 cores (ie modelling a tophat) were incorrectly identifying what was in the web (result was 0 SF capability)
                                            • BUG FIX - discrepency found between 'Stiffener' report and Main ISO report for SF load. Main report was correct; sub report on stiffener was reporting area incorrectly
                                            • FUNCTIONALITY & BUG FIX - streamlined/made more logical the options for adding keelline/sheerline via after main reference surfaces imported ; removed a set of indexing errors (never reported)
                                            •         FUNCTIONALITY - tweaked generation of hull lines to give better ditribution/ dicretisation
                                            •         FUNCTIONALITY - added Ksa, Ksf & Kbm to results table for greater clarity
                                            •         BUG FIX - Simple , homogenous material stiffeners sign convention was incorrectly setting formatting as failing in some cases. No change to calculation numerics
                                            •         FUNCTIONALITY - Added Fbm for simplified assessment of stiffeners. The ISO standard implicitly assumes fully fixed, end of beam, which is the default, but other fixing options are available.
                                            •         FUNCTIONALITY - Added notes and made clearer the effects of stiffener fixing arrangement
                                            Release Notes for Hullscant Version 13.10.21
                                            •         BUG FIX - memory bug found in flangeskin buckling stress calculation
                                            •         BUG FIX - required slenderness ratios were 0 if default material was a core, irrelevant of material in stiffener.
                                            •         BUG FIX - flange skin shear stress (buckling stress calculation) code tweaked to better deal with cores (could get erronous 0 offer stress in a number of cases)
                                            •         BUG FIX - reading in early R1 files (ie pre 2015) caused a div by zero in material properties. Check on modulus value added to resolve.
                                            •         BUG FIX - Stiffeners with sandwich web(simplified method) were , at times, using the core shear stress for the web area requirement (giving required Aw > 10 times expected)
                                            •         BUG FIX - Floating stiffeners, simplified method, were in certain configurations not finding correct tensile design stress, given 0 offered SMo
                                            •         FUNCTIONALITY - Incorporation of effective width plating with stiffener to create laminate for assessment clarified in stiffener library listing (and in code)
                                            •         BUG FIX - importing R1 files with bottom-side stiffeners with a Y=0 caused a non numerical formatting issue.
                                            •         FUNCTIONALITY - importing R1 files, default material is transferred
                                            •         FUNCTIONALITY - streamlined (internally to code) process of assessing laminate stiffeners ((crown+web=>complex ) + plating => full). Results in more accurate calculation of offered properties for some complex laminates
                                            •         FUNCTIONALITY - added 'check for updates' button (in 'About' pull down)
                                            •         BUG FIX - Indexing error in laminates could occur if certain materials deleted from library (esp if deleteing multiple materials at the same time)
                                            •         FUNCTIONALITY - added offset NURBS surface (type 140) to IGES geometry read in (not used by many CAD packages, but..)

                                            Release Notes for Hullscant Version 20.09.21

                                            •         BUG FIX - memory bug found in IGES compound curve (type 102) data structure.

                                            Release Notes for Hullscant Version 16.09.21

                                            •         BUG FIX - If boat had been declared as a workboat, unclicking the "Assess as workboat" was not resetting workboat type to 'none'. Only made a numerical difference for "Heavy workboat".
                                            •         FUNCTIONALITY - added checks on material modulus & strength to beginning of report.
                                            •         BUG FIX - removed possibility of NaN in report for stiffener plating effective width if shear modulus was 0
                                            •         BUG FIX - E/G value for metals was not always being reset to 2.6 (Table A.11), but using actual E/G ratio.
                                            •         FUNCTIONALITY - added checks on internal sizing when reading and updating
                                            •         FUNCTIONALITY - added warning about missing keel, sheer & chine lines where appropriate
                                            •         BUG FIX - adding a default chine line would overwrite a pre-existing sheerline at the same time as adding a chine line; now just adds the chine (not reported by users)
                                            •         FUNCTIONALITY - added listing of design area (and noted where this has been limited) to the report

                                            Release Notes for Hullscant Version 31.08.21

                                            •  BUG FIX - Single skin (enhanced method) was checking plating thickness and checking that ratio when determine warning colour in results report. Removed as not a requirement as per Table A 5
                                            • FUNCTIONALITY - for clarity, ensured BM in report is always +ve (sign convention of ISO12215 results in -ve)
                                            • BUG FIX - Added whitespace between material properties incase a strength > 1e9 is defined, which caused file read issues
                                            • FUNCTIONALITY - added check for stabilsing core material in web and flange buckling, as per Note below table A.12. Core is checked against Table A.7 & Table C.2 12215-7:2020
                                                                    This has resulted in some changes to definition of 'web laminate' in Hullscant for sandwich stiffener structures
                                            • BUG FIX - K dyn limit of 8 (heavy work boats) was being applied to K Dyn stage, NOT K Dyn 1 . Direct calls to K dyn 1 (reduced speed, annex J) were missing this limit. Fixed
                                            • BUG FIX - IGES file import issues; reset beam check to take account of stbd side hullform,
                                                                                    removed bug in auto create sheerline where wrong station X was possible
                                                                                    removed indexing bug if PTR to unrecognised iges type
                                                                                    removed memory bug in drawing type 144 surfaces (not reported by users)
                                            • FUNCTIONALITY - IGES file import; changed method of collection stn points from surfaces to better monitor transverse surfaces (eg transom)
                                                                                    added option to flip points extracted if y < 0 (so we have Y +ve in stn curves)
                                                                                    added ARC (type 100) to list of geometric entites read in
                                            • BUG FIX - added reset to row warning colour in report for stiffeners - it was possible to have warning colour when items passed OK
                                            • ISO STANDARD ERRATA - Table 9 , Area limited to 2.5b^2 for planing craft panels. It was 4b^2 in previous errata, and not limited in published standard

                                            Release Notes for Hullscant Version 03.08.21

                                            • BUG FIX - shear flow calcs for web above neutral axis was using area of web below axis, not area above axis.
                                            • FUNCTIONALITY - reset critical ply reporting for stiffeners to be same as plating (ie inner ply has highest index), and clarified total number of layers
                                            • BUG FIX - critical ply reporting for stiffener shear force corrected (it was repeating the BM critical ply)
                                            • FUNCTIONALITY - clarified stiffener critical ply reporting between upper & lower web for shear force
                                            • BUG FIX - resolved NaN material property when importing (and updating) test data where modulus was missing

                                            Release Notes for Hullscant Version 16.07.21

                                            • FUNCTIONALITY - changed allowed number of layers in a laminate from 100 to 200 (MaxNumLayers)
                                            • BUG FIX - BM shown in layup dialog corrected (BM was equalling 0 when core used) - 3 sub issues resolved

                                                            i) skip core materials (unless structural) in laminates

                                                            ii) layup correctly re defined as sandwich when core added

                                                            iii) skip core materials (unless structural) in complex stiffeners

                                            • FUNCTIONALITY - added ability to change fixing & position on beam in stiffener specification (was hardwired as fully fixed) (incurring file version change to 112)
                                            • BUG FIX- removed memory bug in undo internals (not reported by users)
                                            • FUNCTIONALITY - when reading in R1 file, material names are either appended with "(UPDATED)" or "(IMPORTED)" , and no longer changed
                                            • FUNCTIONALITY - when reading in R1 file, materials with a layup of "vacum bag" are now reclassified as "infusion" (they were being classed as "prepreg void")
                                            • BUG FIX - reading in E Glass test data (from r1 hullscant) is kept as test data; it was being converted to CSM.
                                            • BUG FIX - deleting material with lower index that one used in hybrid stiffener crown / web material caused an indexing error.
                                            • BUG FIX - indexing error in report if user deletes used laminate (not reported by users)
                                            • FUNCTIONALITY - changed default answer to 'No' when importing IGES and asked if it is to be moved to x=0
                                            • BUG FIX - Web & flange slenderness ratios were appering as "NaN" if flexural strength was 0. Chacks added to give result of 0 instead

                                            Release Notes for Hullscant Version 07.07.21

                                            • Coded to latest ISO standard 12215-5:2019.
                                            • First version of HullScant Release 2.




                                            Release Notes for Hullscant Version 23.01.18

                                            • Removed bug restricting some historical files from being fully compatible with current release.
                                            • Last version of HullScant Release 1, now withdrawn from sale. Installer available to existing Release 1 clients on our Customer Download Area

                                            Release Notes for Hullscant Version 26.09.17

                                              • Removed occasional bug in pull down menus for HTML results.
                                              • Removed issue with reading legacy BST files relating to decimal separator.
                                              • Compliant with Windows 10 up to and including version 1703.

                                              Release Notes for Hullscant Version 14.10.16

                                              • Corrected link to HTML help files.

                                              Release Notes for HullScant Version: 03.08.16

                                              • Modified skin stiffness equation for cases where skin wrinkling occurs.

                                              Release Notes for HullScant Version: 30.06.15

                                              • Help system and context-sensitive help upgraded to Microsoft HTML Help (.chm) format.

                                              Release Notes for HullScant Version: 25.05.15

                                              • Removed bug in calculation of torque carried by a ‘combined’ stock and blade rudder.

                                              • Clarified and improved metal material property selection and usage in rudder module.

                                              Release Notes for HullScant Version: 14.03.12

                                              • The ‘Pass Warning Ratio’ parameter found in the ‘Boat Particulars’ dialog was not saved to .bst. This has now been fixed.

                                              Release Notes for HullScant Version: 01.08.11

                                              • Under some Windows 7 font settings the ‘Material Name’ column in the Laminate window was not shown. This has now been fixed.

                                              Release Notes for HullScant Version: 31.05.11

                                              • The aspect ratio shown in the ISO Scantling Report was found to be inconsistent with the actual aspect ratio used in the scantlings calculations. This has now been corrected.
                                              • For cored panels with aspect ratios greater than 4, the calculated kSHC was incorrect. This has now been fixed.

                                              Release Notes for HullScant Version: 05.04.11

                                              • If converting a hybrid wood/FRP stiffener to a complex stiffener a warning will now appear indicating the effective breadth factor is 20.
                                              • In calculating the web thickness for an FRP stiffener in the Stock Stiffener dialog the formula uses 0.3 default for the fibre content. This has now been changed so it uses the actual FRP fibre content.
                                              • In calculating the minimum thickness requirement, tmin, for hull and sides with an offered laminate, Hullscant would use FRP calculations even for wood sheathed with FRP, for example. A further option has been added to the Reinforcement Type dropdown on the Offered tab of the Panel Requirements dialog to set this to wood. Hullscant will then use the wood equations accordingly. For a laminate of wood type, Hullscant will also remove the weight requirements for the outer and inner skins.
                                              • In calculating KSHC, Table 12 for cored panels, this value was limited to 0.465. Hullscant now includes an additional curve for 2<(l/b)<4.

                                              Release Notes for HullScant Version: 29.09.10

                                              • For large panels (section 8.4 of ISO12215-5) located over the bottom and the side, Hullscant will not apportion the pressure for the bottom and side accordingly.

                                              Release Notes for HullScant Version: 09.09.10

                                              • For structural bulkheads the transverse position may now be entered and displayed in the boat view window and the water head is also shown by a blue line.
                                              • Section 8.4 of ISO 12215-5 for very large panels has been added to HullScant. The results will show a warning if this Section has been invoked.
                                              • For a single skin laminate built using the laminate builder the tmin in some circumstances could be presented as the minimum weight. This has now been fixed.
                                              • The kar value in the results were generally displayed for the displacement mode only, this has now been changed so it reflects the value for displacement, planing or cored panels.

                                              Release Notes for HullScant Version: 30.07.10

                                              • The k6 option for the sandwich minimum skin care factor has been added to the program. This can be set in the Boat Particulars dialog.
                                              • Hullscant Rudder: for the main rudder stock type, the option would not be set when reloading a file. This has now been fixed.

                                              Release Notes for HullScant Version: 06.07.10

                                              • For a particular set of circumstances related to the Undo function HullScant can encounter a library indexing problem. This has now been fixed

                                              Release Notes for HullScant Version: 05.05.10

                                              • For Hullscant Rudder a laminated stock was not recognised if it did not have a corresponding laminated rudder blade. This has now been fixed.
                                              • For laminates without a core on rare occasions the skin wrinkling stress can cause what looks like a non-compliance even though it should not be considered for non-sandwich laminates. This has now been fixed.
                                              • For a stock L shaped stiffener the web area included the angle. This has now been changed to remove this thickness.

                                              Release Notes for HullScant Version: 09.02.10

                                              • Optional Hullscant Rudder module now available. Hullscant Rudder calculates the structural properties of a vessel’s spade rudder, and compares it to the requirements of ISO 12215 Part 8.

                                              Release Notes for HullScant Version: 07.01.10

                                              • The frp ply thickness, tMIN, calculated from the weight of the fibre was based on an assumed resin specific gravity of 1.2. This calculation has now been changed to be the ratio of the required fibre weight over the actual fibre weight times the actual thickness of the ply to remove the reliance on resin density.
                                              • The reverse laminate order option in the Laminate dialog can create an error in some circumstances. This has now been fixed.
                                              • In rare circumstances the wrinkling stress ratio of the inner skin of a sandwich laminate may not be recognised as the lowest stress ratio. This has now been fixed.

                                              Release Notes for HullScant Version: 02.12.09

                                              • The frp ply thickness, tMIN, calculated from the weight of the fibre had an error that could affect the calculation. This has now been fixed.

                                              Release Notes for HullScant Version: 03.06.09

                                              • The Longitudinal pressure distribution factor, KL, was not shown for deck panels and stiffeners. This has now been corrected.
                                              • The kar factor for sandwich panels in a unique set of circumstances could be greater than the 1.0 limit. This has now been corrected.

                                              Release Notes for HullScant Version: 30.04.08

                                              Relates to ISO 12215-5:2008, Date 2008-04-15

                                              • Updated titles and footers in program to match title of final ISO 12215-5:2008, Date 2008-04-15 International Standard.

                                              Release Notes for HullScant Version: 21.04.08

                                              Relates to ISO 12215-5:2008(E), Date 2008-01-04

                                              • Updated program to match changes in new ISO 12215-5:2008(E), Date 2008-01-04 International Standard.
                                              • Updated HullScant to match ISO 12215:5 Table 3.
                                              • Updated HullScant to match ISO 12215:5 Table 18.
                                              • Added curvature correction to ISO 12215:5 Table H3 to match equations 38 and 39. This is an omission in the standard.

                                              Release Notes for HullScant Version: 29.11.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • In factors for the minimum thickness and skin fibre mass requirements there is a speed dependency. This has now been set to 2.36*LWL1/2 for sailboats.
                                              • If the neutral axis of a stiffener moves into the plate or the flange then the offered shear force results can be too high. The offered shear force form formulation has therefore been changed and relies on the web only. For hybrid or complex stiffeners there is now a drop down box in the corresponding dialog/window that describes the stiffener configuration to aid the calculation for a shear force factor. If more precise information is required regarding this formulation then please contact the Wolfson Unit.
                                              • The HullScant file format has been changed (FV20), older HullScant files will work with no problem but new files cannot be used with older versions of HullScant.

                                              Release Notes for HullScant Version: 14.09.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • Following a request for intepretation the addition of a requirement for the laminate weight of the inner and outer skin for the superstructure and deckhouses location has been added back in to HullScant. There is also a requirement for tmin for other material types for superstructure and deckhouses.
                                              • Every time the stiffener properties results are calculated for a hybrid/laminated stiffener and there is a bondwith set, the height of the web laminate will be subtracted from the height of the stiffener. This has now been fixed.

                                              Release Notes for HullScant Version: 12.09.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • Added view scroll buttons to cycle through the views on the boat view window.
                                              • The wrinkling stress calculation for the laminate analysis can be incorrect for some circumstances. This has now been fixed.
                                              • When using sandwich laminates for locations other than bottom, side and deck, Hullscant wrongly shows a requirement for the weight of the inner and outer skin. There is no requirement for other locations. This has now been fixed.
                                              • Laminates in the laminate library cannot be deleted, even if they are not referenced in a panel or stiffener. This has now been fixed.

                                              Release Notes for HullScant Version: 18.07.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • There is now the facility to copy the boat view to the clipboard. The view will be copied at the size and aspect ratio of the boat view window. See the Edit, Copy View to Clipboard menu item when the boat view window is selected.
                                              • The top hat stiffener weights in the weight estimate now include the additional weight of the panel at the base of the stiffener as this is not included in the adjacent panels.
                                              • The panel and stiffener weights in the weight estimate now include an additional curvature factor. The shape of the panel or stiffener is assumed to be a circular arc.
                                              • Additional important information has been added to the weight estimate report. Please see Help, Process Description, Weight Estimate for more information.
                                              • For Hybrid/Laminated stiffener types with a bond laminate width set, the mechanical properties can be marginally overestimated as the bonding laminate thickness is not removed from the web overall height. This has now been fixed.

                                              Release Notes for HullScant Version: 24.05.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • The off face grain angle in the plywood dialog was not enabled when plywood on edge is selected. This has now been fixed.

                                              Release Notes for HullScant Version: 22.05.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • The output thickness of complex stiffeners can be missing the last layer if that layer is a web part. This does not affect the Hullscant calculations. This has now been fixed.
                                              • Wrinkling stress ratios for laminates were calculated on the basis of individual ply modulus, this should be the thickness weighted modulus of the whole inner skin. This has now been fixed.
                                              • In the panel stress ratio results the minimum ply was displayed in the failure colour. This has confused some users and therefore has been changed to not display a colour.

                                              Release Notes for HullScant Version: 17.04.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • For floating stiffeners there is an error in the ISO standard equation (51) such that the kSA factor should always be 5 for hybrid/laminated or complex stiffeners using the required shear force and shear flow methods. This has now been corrected in Hullscant.
                                              • There are some indexing errors that can occur for particular circumstances when editing sitffeners or materials. This has now been fixed.

                                              Release Notes for HullScant Version: 16.04.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • An indexing error can occur if you have more laminates than materials and they are offered to a plating requirement. This has now been fixed.
                                              • The required web thickness for complex stiffeners can sometimes be 0 in error. This has now been fixed.
                                              • The hardwood shear properties in Table E.1 of the curerent ISO standard version are rounded to integer values. These have been changed in HullScant to reflect the values.

                                              Release Notes for HullScant Version: 23.03.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • Added non-ISO12215 capability for adding wood properties perpendicular to the grain direction. See the Wood dialog. Please note the following disclaimer: The perpendicular-to-grain values are for indicative purposes only and are not taken from ISO-12215 as the standard provides no data. It is strongly recommended that actual test values be used for design purposes. The Wolfson Unit MITA accepts no liability for the use or accuracy of these values.
                                              • Added non-ISO12215 data for Wood shear modulus data. Wood Shear Modulus = 1.6 x density. This is required when wood is used in a hybrid/laminated or complex stiffener.
                                              • Added icons to the Panel and Stiffener requirements windows to indicate the offered material or stiffener type. This is only available when in the "Details" view of the window.

                                              Release Notes for HullScant Version: 06.03.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • Added a copy button to the GRP multiple laminate dialog for copying previously created layers in the laminate.
                                              • Added a weight estimate tool button on the Main window.
                                              • Changed the layout of some dialogs, particularly Plywood dialog as users are not finding the Plywood on Edge option for building stiffeners.
                                              • If you use the sorting in the Materials library, Stiffener library or Laminates library and then select "No" to saving the changes to the library, there can sometimes be an indexing error in the respective referenced items. This has now been fixed.

                                              Release Notes for HullScant Version: 27.02.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • The results now include a full web shear buckling check as per section 11.7.2 and Tables 20 and 21. A warning will appear in the results if the web is likely to buckle in shear.
                                              • The results window and various library windows now retain their sizing and window state (normal,maximised or minimised) after closing and reopening in a single program session.
                                              • There are extra sorting options for the required panels, required stiffeners and materials library windows using the layout menu or move up/move down tool buttons.
                                              • There are now sorting options for the Laminate library and Stiffener library using the layout menu or move up/move down tool buttons.
                                              • Added a weight per unit area column in the Materials Library and Laminate Library Windows.
                                              • Updated the Boat View window, changed presentation of selected structure and overall presentation differences.

                                              Release Notes for HullScant Version: 20.02.07

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • The area pressure reduction coefficient kAR has been added to the results in the ISO Calculations columns for panels and stiffeners.
                                              • In the laminate window, for some symmestrical layups the minimum bending moment can appear as zero. This has now been corrected.
                                              • In certain dialogs the materials drop down box can sometimes be too small for certain types of materials. These have been increased in width where appropriate.
                                              • If a stock stiffener is FRP and it is first in the list it will not show the Stiffness - (EI) requirements for FRP stiffeners in the results. This has now been corrected.
                                              • For single skin panels designated as "bottom and side" there was no required tmin. This has now been corrected and requires tmin as for a bottom panel.
                                              • Added the ability to enter wood material shear modulus data in the Materials Library dialog. This is requred for hybrid/laminated or complex stiffeners or sandwich panels with wood.

                                              Release Notes for HullScant Version: 27.11.06

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • Corrected units output for EI and BM in Laminate Window when editing a stiffener.
                                              • If a stock stiffener is not FRP the ISO report will indicate that it is a pass/fail warning when it actually passes. This is now corrected.
                                              • Hullscant relies on an HTML browser plug-in for the results page. There has been no indicated problems using the new Internet Explorer 7

                                              Release Notes for HullScant Version: 09.11.06

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • For stock stiffeneres, plate effective width - be, has been updated in HullScant to correctly reflect Table 19 based on material type rather than stiffener shape.
                                              • If a stock stiffener is specified as floating or other arrangement then the effective plate width will be 0 such that there is no contribution to area, section modulus or inertia from the attached plating.
                                              • In the materials properties results, individual GRP multiple laminate schedules are tabulated below the materials properties.
                                              • In the laminate window the inner and outer plys are indicated on the laminate diagram.

                                              Release Notes for HullScant Version: 13.09.06

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-08-24

                                              • Checked to include newly released standard equations and nomenclature as version stated above "Final FDIS Draft"
                                              • When adding strip planking, material title includes sheathing details

                                              Release Notes for HullScant Version: 04.08.06

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-06-15

                                              • When loading a file with Carbon double-bias or quadraxial in the materials library, the weave will return to woven roving or crossplied fabric. This has now been fixed.

                                              Release Notes for HullScant Version: 25.07.06

                                              Relates to ISO/FDIS 12215-5:2006(E), Date 2006-06-15

                                              • For a hybrid stiffener effective plating width only used calculated effective plating width (20tp + bb) and not the lesser of this or the stiffener spacing. This is now corrected
                                              • Inner skin wrinkling stress (Section 10.5.3 of ISO Standard) is now displayed in the Panel Stress ratios in the Results window
                                              • Panels may be analysed now in long direction (Annex H). Refer to offered tab on panel requirement dialog, also Orthogonal Panels in the Process Description section of the Help File
                                              • Added data for shear modulus of Quadriaxial and Double-bias Glass and Carbon as it is unavailable in the ISO Standard, this is required for stiffeners.
                                              • Laminates may be re-orientated by 90 degrees using the Add menu in the Laminates Library window. Refer to Orthogonal Panels in the Process Description section of the Help File
                                              • The decimal separator has been hard set to a point (.) to avoid errors with compiler when windows regional settings has a comma (,).
                                              • The curvature label in the ISO stiffener report and weight estimate report had the units of metres when it should actually be labelled in mm (millimetres). This is corrected.