Surface

There are no special modifications to Surface, but all the structures exposed to the wind, must be defined as compartments and assigned to special category with an ID of "SL" and title, "Sail". It is important to use the identifier "SL" for the "Sail" category, because Calc checks for this when calculating wind forces.

It is also necessary to calculate the lateral force below the waterline, so the underwater structure must also be defined in the "Sail".

Compartments can only be assigned to one category, so it is necessary to duplicate the watertight structures when defining the "Sail", by copying and renaming these, before assigning them to the "Sail" category. Writing a macro to do this should be possible.

Extra structure that does not form part of the watertight hull, should then be added as "Sail" compartments.

To facilitate editing in Calc, a naming convention that groups the "Sail" compartments together alphabetically, is recommended.

The geometry should be released from Surface in the usual way.