> Under the heading "General Intent" - "Dimensions should be
> increased where special considerations of design or service make it
> advisable". I believe that the possibly of surf landings and more
> than occasional rock impacts are special considerations of service.

This is kind of a no-brainer, if you are going to treat the boat rough, build it tough. Everyone will have to make some sort of judgement about how they are going to treat the boat. I would not design a boat for rare extreme occurances unless I thought there was a significant chance of it happening. I.e. if you are only paddling on a small lake, surf landings should not be engineered into the boat. If you spend a lot of time on the ocean or Great Lakes, and won't always have control over your landing, you should plan on a few surf landings and build the boat to handle some hard hits. If you are somewhere in between you will have to judge what you need. After you build it you need to use your own judgement as to whether you or the boat are ready for the conditions you intend to head out in.

The scantlings seem to assume the occasional impact with rocks and pilings and, if applicable to a boat the size of a kayak, should give a layup that is sufficient for the occasional impact. From my discussions with him, Tom McNaughton seems to feel that the scantlings are applicable to low displacement boats such as a kayak.