Steve- Did you see the posts over the last 3 or 4 months about the Sea Pups? I think the design, (done by Tom Yost) perhaps modified somewhat, would be very good for what you're doing. As you may know, we built four of these with dads and sons, and they are truly excellent boats. Our costs ended up being about $150 per boat, but I think that could be trimmed down in various ways. You need strongbacks, but you could build in 'batches', re-using the strongbacks. The Sea Pup is designed at 19" beam, and only one of the boys has flipped his over. (Repeatedly!) I think if you took the design and expanded the beam to about 22", they'd be very stable. Actually, for some of the smaller boys, I'd think the 19" would be fine, but they are a bit tender for a big beginner. Of course, you'd want to keep the seats as low as possible. Regardless, I think you couldn't go wrong with the fabric we used- the PVC stuff that they use to make the 'moon bouncers' that show up at kids' birthday parties. It was only $5 per 61" wide yard, and once it's glued, you're done. Patching is ridiculously easy, and would be ready in minutes. If you have any questions about the design, feel free to email me. Keep us posted on the project. Best of luck- I can't think of a better way to create some great memories for the boys. Steve Phillips