One of the arguments against a rigid bulkhead is that a rigid bulkhead would cause a stress riser at the hull junction. Should you have a major impact, or a sliding impact, as one might expect getting raked across a rock by a surge, then you could expect major failure. If you had a foam bulkhead, then you could expect less major failure, as the foam would give.

A friend once considered one of the Hawk models in fiberglass. I forget which one, it was probably the middle sized one that Wilderness Systems (I think) used to make. He wanted it with rigid bulkheads, but the manufacturer wouldn't do rigid, and would only do foam. The MFG quoted this reason for wanting to only use foam. I think it was just that the MFG wasn't set up to do a glass bulkhead.

I personally think this is a non-argument - impact of sufficient magnitude in the bulkhead area is going to be a problem no matter what. I also think that strip built or reasonably strong stitch and glue layup is going to be plenty strong to make a rigid bulkhead a non-issue.

I'm sure anyone beating up their wood construction boats in rock gardens would tell us similar.

Brian

: Why not be a purist and use wood?

: Et