If you were building a hull entirely out of wood there might be a difference. But encapsulated between layers of epoxy/glass it should work well as anything else.

: So I just stopped by my favorite sawmill up in Revelstoke, BC and
: picked up some really nice clear red cedar 2x6's. The grain is
: absolutely perfect, but the boards are about half sapwood.

: Is there any significant structural strength difference between
: heartwood and sapwood in WRC? How about in terms of bending and
: splitting?