under floor fuel tank

[gilligan]

I have a 17 and half foot pongrass half cab. I have just put a 2001 merc 115 hp on the back. I renewed the transom with hooppine marine ply. I repaired the floor about 5 years ago with new marine ply and fibreglass over the top and one of the corners are lifting. the bottom of the marine ply has slight rot and I have decided to rip it up and renewit. I want to put in a Aluminium fuel tank under the floor. I am chasing advise on whether it is possible and how to reinforce and pad the tank so it will be a safe option. I doo a lot of offshore fishing and want to make it safe.I now have external tanks but I want to use that room for other accesories.(bait tanks,Iceboxes etc.)

[paladin]

first, what are the dimensions of the proposed tank...and are you going to purchase it or make it yourself....and may I assume the boat is fiberglass or is it wood....if made from aluminum there are minimum thicknesses for the metal, then baffles must be considered....then the weight of the fuel will determine the bracing needed below the tank....with aluminum there will be pitting in time so it is suggested to coat the inside of the tank with coal tar epoxy...so many questions...so little time...

[George Ray]

If you have a glass hull, foam is an option for tank installation. Foam (2-part polyuratheane) will cradle/hold/nestle/secure an aluminum tank so well that you would have few worries about the fuel tank shifting while leaping off wave tops as your racing a summer squall line back to harbor from the fishing grounds. Plastic conduit in place below and beside the tank before the foaming would allow normal fore&aft flow of air/water/wiring/hoses etc. We are very pleased with our 19 BW outrage that has 60gal alum tank in the bilge.

[rbgarr]

Why aluminum tank? Are you getting a custom shape?

I'd feel safer with a stock cross-linked polyethylene tank under a closed in deck, mainly because of the potential poultice corrosion problem with aluminum tanks since you can't inspect them often.

[Peter Malcolm Jardine]

A large boating store with a W at the beginning sells tanks in plastic and aluminum. No reason not to use plastic. Then, what Paladin said.