Is it possible to use 'exterior' grade plywoods which are much cheaper than
marine plywoods? You could use a glass resin or just a strong yacht varnish
to weather it.
I'm building a 12 ft sailing boat. I used white deal to build the frames and
a bit of parana pine for the keel (which I may have to remove because it
might swell).
But using 6 sheets of 'marine' plywood will break the bank.
For six sheets of 8x4 ft plywood I will fork out up to 600Euro (which is
close to 600 US dollars).
'Exterior' or some lesser grade might be half the price or even less and
might work with a few extra coats of paint!!
Will it work??

MT. Ireland