I tried drawing a folding canoe a few years ago but thought twice about it, thinking little canoes are easy to stow even when they don't fold. But I mentioned it to Dave Carnell who has been boating for many years and never throws away a boating magazine. He sent me copies of two folding boats that appeared in "how to" magazines, especially Boatbuilder's Annuals that Science and Mechanics used to put out generations ago. One of those boats was "Handy Andy". How old is the Handy Andy design? This year someone gave me a 1948 copy of the Boatbuilder's Annual and Handy Andy is in there. I'm guessing many designs in the issue go back into the 30's since one might think that boat designers had other things to do in the early 40's. Handy Andy used modern plywood, probably better plywood than we can get today, and used canvas to seal the flexing joints.
Modern folding boats like the Portaboat look like they use flexible plastic sheets at the folding joints, something the home builder won't be able to use. So I went back to the Handy Andy technology which used common metal hinges to make structural joints between panels with waterproof fabric to seal the water out. Where Handy Andy used canvas I would suggest something like Aqualon which is very tough and totally waterproof by my experience.
The layout of a folding boat requires that the joining panels have exactly the same curve which is why most folding boats look pretty spooky. Folderol2 is done that way and to keep it simple I made it the same fore and aft. It is very short at 6', the absolute minimum for two adults. You can imagine a standard bathtub to get an idea of the size. When folded up it will be 6' long, 18" wide and maybe 6" deep. The usual talk will be that you could carry it on your "cruiser" to walk the dog or get the groceries. Maybe so, but I think the real use will be for apartment bound folks who will keep one folded up in the back of the vans, etc.. It could stay there all the time ready to go, quite out of the way.
Well, I think Folderol2 is a very experimental boat. The fact that the idea never caught on even though Handy Andy has been around for fifty years might mean something. The seals will be Ok given care in gluing to the panels. I'm not certain how well the folding system will work. I'm not certain how sturdy it will be since the panels have to be flexible enough to stow flat and still bend to shape on demand. But when used for minimum rowing the structural demands should not be great. Forget about using a motor or sail on it.
Folderol2 uses two sheets of 1/4" plywood and sixteen hinges by my count. The amount of frabric required is not a lot. I think the fabric will be glued with contact cement and the seam battens bolted over the glued joints just to be sure, as was done with Handy Andy. I suppose today's glues are a lot better than the old glues and the seam battens might be overkill. Then again, if I had one of these I would be sure to have a roll of duct tape with me just in case.