Timbo good question.

As a 4 x 8 sheet - the foam is stiff and a sheet of ply would bend more. The foam would shape with pressure or heat. They also have foam that is scored into about 1 inch boxes with a scrim. Having said that you cut the foam in a thin enough strip you can take an 8-foot strip and wrap it into a loop.

You have to select a starting point to begin and build from that point. The obvious point for me is the chine. The strip at that point bent on two axes rounded out and rounded up. There is not a straight or flat line on the hull. I found a 1-3/4 inch strip to bend well in all directions except for last foot of the stern. I wanted the maximum size strip that would fit well and lay in the curves. Wider strips would have more faring and fill, to make round.

The other thing to consider is the set-up. The saw is not too bad. The router is another story, it has 4 adjustments and they are pretty exacting. Once it is dialed in I don’t like to change the setting. At about $100 a sheet of foam you don’t want a lot of waste.

The Ama’s may use wider strips as they are a traditional shape and don’t have compound curves.

If you notice the black mold in the background pictures of a 34-foot hull you could use full sheets on that type of mold so it also depends on the type of mold you build. A male mold or mold with longitudinal runners in it could use the sheet style. So there are factors to consider when looking at designs and selecting building method and medium. The strip foam method is pretty popular for a “One-Off” boat. Are you thinking about building a boat?