Advanced design software for mastering ship geometry

Go to Help Summary                                                                                                                                                                                                  Go to FAQ Summary


 Menu bar/ToolsWoD Stability 




          Stability calculations with water on deck (Stockholm Agreement) assume that the car deck may be flooded by waves according to its residuary freeboard, calculated with reference to their significant height Hs.

          In order to achieve this special stability calculation, the dedicated ‘WoD Stability’ function automatically adds the necessary water on the car deck, according to the entered data and selected script. As this special process is not supported by the standard ‘Transverse Stability’ function, don’t try calculating WoD stability with the ‘Transverse Stability’ function (no water will be added on car deck) and don’t try calculating a standard stability with the ‘WoD Stability’ function. 

          In order to make this automatic process possible, a few simple modelling rules must be respected (see the FAQ for more details) and the selected criterion must include a special header specifying the car deck flooding rule (i.e. the DefineSubmersionRange  / DefineSwellRange commands. See ‘STC Scriping Manual’ for more details and the ‘SOLAS 2004’ criterion for example). 

          If necessary, the WoD stability can be automatically calculated for all the present damage cases thanks to the ‘Deterministic Stability’ function, provided that the calculated damages comply with the WoD modelling rules.

          In this case, attention must be paid to the fact that the damage longitudinal extents must preliminarily be set individually in their ‘Xmin’ /’Xmax’ fields on the [Data] page

          WoD stability calculation is refused if current ship doesn’t comply with the required modelling rules (i.e doesn’t contain a ‘car deck compartment’ set in the ‘Water on Deck Layer’ and a car deck margin line set in the ‘Freeboard Layer’, as shown below). It is important to notice that car deck’s margin line(s) doesn’t need to be affiliated to it and that the selected ‘Water on Deck Layer’ must have flooding water’s density, as it specifies water on deck’s properties

WoD Modelling



    The following dialog box pops up when the function is selected:

WoD Stability DB


          The [Criterion] button allows selecting the WoD stability criterion among the available STC scripts (the associated data must be set after this selection). As explained above, the selected criterion must include a special header specifying the car deck flooding rule (see the ‘SOLAS 2004’ header criterion for example).

          The ‘Heel Range’ ‘Min’, ‘Max’ and ‘Step’ fields allow defining the stability heel range to calculate. This range must, of course, be thought in order to allow calculating the selected criterion. 

          The ‘Side’ selector allows defining on which side the stability has to be calculated.

               The ‘List Data’ check box allows including / removing the stability data listing associated to the diagram (see 3.20.c.2 below).

               The ‘Show Free Surfaces’ check box allows including / removing the Cargo / Floatation free surface report (see 3.20.c.4 below).

               The ‘List Loading Case’ check box allows including / removing current loading condition’s analysis (see 3.20.c.3 below).

               The ‘Calculate Max KG / Min GM’ check box allows including / removing the Max KG corresponding to the selected criterion in stability diagram’s header (see 3.20.c.1 below).

               The ‘Show Silhouette Analysis’ check box allows including / removing the Silhouette analysis diagram at equilibrium (see 3.20.c.5 below). These data correspond to ‘/Tools/Silhouette Analysis’ report.

               The ‘List Calculated Lines’ check box allows including / removing the information (dimensions, freeboard at equilibrium, angle of immersion) concerning the current freeboard and openings descriptors (see 3.20.c.3 below).

               The ‘Show GZ / Metacenters’ check box allows including / removing the Body plan / GZ polar / Metacenters curves (see 3.20.c.6 below).

          - The ‘Significant Swell Height (Hs)’ field allows entering significant swell’s height, according to its Stockholm Agreement definition. 

          - Damage’s longitudinal extent is defined by its ‘Xmin’ and ‘Xmax’ limits (according to the regulation, car deck’s minimum freeboard is only calculated between these limits). 

          The ‘Output Document Name’ input field allows naming the 2D folder in which the resulting reports will be created in the 2D browser.


          At last, when all the stability input data are set: 

          The [OK] button can be clicked for calculating ship’s data and creating the corresponding report. Nevertheless, as this calculation may be time consuming, a  confirmation box recalls the number of stability calculations before starting. 

          The [Help] button allows displaying the online help (Internet access necessary). 

          The [Cancel] button allows cancelling the calculation. 

          Pressing the [Escape] key when calculation is started allows aborting it.



            TheWoD Stability outputs are the followings:

 Typical  Dredge Stability Curve:

 WoD Stability Curve

WoD Stability ListingWoD Stability Listing:


 Line and Load Analysis:

Line + Load Analysis


 Free Surfaces Analysis:

Free Surfaces Analysis


 Silhouette Analysis:

  Silhouette Analysis


 GZ / Metacenters Diagram:

GZ / Metacenters Diagram


          The calculated model must comply with the Water on Deck modeling rules (see the FAQ for more details) and be realistic in terms of weight and buoyancy. 


Typical use:

           Calculating stability with water on deck (typically SOLAS 2004 / Stockholm Agreement).



-        Open a project complying with the Water on Deck modeling rules and select it to calculate its stability data: 

-        Select '/Tools/WoD Stability' in the menu bar.

-        Click on the [Criterion] button, select the ‘SOLAS 2004 Stockholm’ criterion, and validate it.

-        Input criterion’s associated data in the right grid.

-        Input a realistic heel range in the ‘Min’, ‘Max’ and ‘Step’ fields.

-        Set the damage extent in the ‘Xmin’ / ‘Xmax’ fields.

-        Click on the [OK] button and check the obtained reports.