by Wobbly Wheels » Sun May 22, 2011 8:42 am
It's pretty common to do it that way in sailboats so you can take advantage of the odd shapes along the hull. If you're going to use styrene resin, the INSIDE of the tank needs to be gelled because fiberglass isn't waterproof and the smell of a black or grey tank will get out.
Now most are done with epoxy because for all intents and purposes, epoxy is 100% waterproof and doesn't impart any flavour to your water once it's off-gassed. I mix the resin with about 5-10% less hardener than the ratio calls for and cure it under heat lamps. That's because the (unmixed) hardeners contain BPA. Once the reaction occurs from mixing, that threat is gone, so the slight surplus of resin insures there will be so uncured hardener...just in case.
Build your tanks however you'd like, fillet the inside corners and use some epoxy with 6 oz cloth. I've been thinking about a water tank as part of a tongue box shaped like a pirate's chest, lol.