: But before you go to the trouble of building one- why don't you
: just pick up a used Pirouette for $100 and cut the seat out?
: Cheaper, less time, you can bang it on the doors on the way into
: the pool, and you can seal launch it. They're shaped like a log,
: roll right around. You can put a student in there and not have
: to worry about them catching their feet on the bulkheads/ribs in
: a wet exit.

I think Mike's comments are excellent.

I'd like to add:
-A plastic (rotomolded) boat would be a lot more rugged than anything you could build, and would stand up to the banging/transport/dragging hulls over the deck that pool sessions entail.

-As a retired high-school teacher, I'd suggest that you use a boat that's as similar as possible to the ones your students will be using. Otherwise, your students will be thinking that your success (and their trials) are due to your 'better' boat. Your pic shows all the students in sea kayaks.

Grabbing a plastic sea-kayak would be my recommendation. Even if it requires shipping or a weekend of driving, it will end up being cheaper and less time-consuming than building a boat- even a SOF boat. And, it will work better in the pool than a boat with float bags or a sea-sock.