The part that lacks contact is the small perimeter which indents to form the thigh brace.
A properly fit neoprene skirt stretched over a thin profile of wood or fiberglass can get a good seal. Rotomolded kayaks have a large profile radius with a shallow lip, the large rubber rand skirts evolved to get a water tight seal. My observation, which may not be valid to the NDK lip, is that without sufficient contact at the rand I can get blow by at the thigh form indent in heavy WW or from water forced into the lip while surfing.

Overall I think Bryan H. is onto a good idea and the seal can be considered in the design. I also think this would work best if it is not the first build of any one model. I prefer to match the kayak to my natural body position, rather than forcing my body to match the kayak parts.

Best,

Reg

: I don't understand. It appears from photos (the one you posted as well as the
: results of google image search) that there are no truly straight lines on
: the NDK coamings with at least a slight curve present along the slides.
: But perhaps the periphery of the coaming isn't what you and the others are
: referring to? The NDK coamings also seem to have a significant horizontal
: curvature, being lowest at the back and curving upward to the front of the
: coaming. That must surely help form a seal with the spray skirt? I don't
: see how the inside profile of the coaming to form the knee braces has
: anything to do with the seal of the spray skirt. The spray skirt doesn't
: "care" about how deep the coaming lip is, as long as a minimum
: for effectivenenss is maintained.

: Quite probably I'm not fully comprehending something.

: Cheers,
: Bryan S.