The Open Boat

The Open Boat presses so many of my buttons it is like the Lost Chord of rowing for me. It is extremely clever and favours simplicity, economy and speed of construction over any considerations of craftsmanship or good taste. And the inventor, Jim Flood, is a rowing coach in Reading. As I only this Sunday qualified as a rowing coach (albeit at lowly Level 2) this makes him a comrade in arms.
It is made of a metre-wide, inch-thick sheet of a foam plastic normally used to crate up electronic equipment for shipping. Jim Flood simply folds the ends up, welds them together to make a bow and stern, and attaches lengths of pine as gunwales. I particularly like the way he doesn't bother with fussy details like sanding or varnishing - when the boat hits the water all the wood is finished exactly as it left B&Q.

The Open Boat seems to row just fine (make sure you watch part 2 of the video here) but there are some technical issues that might need to be addressed before the design can be regarded as totally finished, which are discussed in depth by the experts on the excellent Duckworks forum.
Jim Flood has a link on his site to the extraordinary sturgeon-nose canoe of the American Ktunaxa Nation, which may indicate a shape that would bring the bow up and reduce the hogging in the centre of the boat that the building method tends to create.
Jim's aim is to create a sliding seat rowing boat for developing countries, but I want to know how this method can be adapted for beamier fixed seat boats. It would involve either obtaining sheets of foam wider than a metre or welding two sheets together I suppose. Any ideas?