You should be aware of the following limitations when creating decks.

The waterline you select to define a deck must form a single continuous closed contour around the surfaces of the design.  For best results you should be sure to define a transom surface when defining decks which extend to the stern of your design.

If you are using trimming, the deck shape will correspond to the trimmed shape of your design if trimming is turned on when calculating decks.

Skin thickness is not deducted from the deck’s perimeter.