How do you know the beam increased with the interior wet-out? That's a new one on me. Might it have been wider before you started glassing? Usually moisture will quickly cause a wood surface to expand, but I haven't seen this with epoxy.

I don't work with carbon fiber so I don't know how that might effect the lay-up, perhaps Nick has had this experience also.

The Petral is a very hard chine hull. I'd be surprised if it expanded and additional 2". If so, that could change the hull shape and forcing it to fit the deck will only compromise the deck shape also.

My approach would be to use pieces of 2" packing tape spaced every 12" to bring the hull to the correct width and see how that goes. If that looks good, I would hot glue 1 x 2 wood struts across the hull interior in a way which will allow you to glass the deck on. THEN install bulkheads before removing the struts.

I know it might seem like over kill, but I spend a lot of time on the rocky shores of Georgian Bay, Ontario, and seem to always be banging off the rocks.

I've paddled on Georgian Bay for more than 25 years and use a single layer of 4 oz. S-glass on my hull exteriors. Oh, and I do try to miss a few of those rocks, but as you know, ain't easy! But even with 100 pounds of gear for week I've never had a rock find wood. The rocks and mussels are sharper in Maine, still no worries!

Where do you paddle GB? Have you seen my GB trips @ http://www.laughingloon.com/trips.html

Good Luck!
Rob