My last kayak has a coaming steam bent of southern yellow pine... maybe not optimum, but ya do what ya gotta do... considering your post, I'm definitely gonna try spruce for ribs in the next one. I've been using spruce for stem boards, and I am re-skinning a year old kayak with spruce stems used hard and put up wet, and the stem boards are in great shape, and I don't think they ever really dried out in between paddles -- the ends were damp when I cut the skin off, and had been sitting on the rack for nearly a month. Had no oil or varnish either, just plain wood. It's pretty difficult finding the hardwood with requisite grain around here, but I can get good grain in spruce or pine everywhere. Neither are supposed to be very rot resistant woods.