Fuel Tanks

[Basketcase]

Hey guys. I just aquired the stripped out hull of a 20' center console. All I have is a hull and stringers. First on the agenda is to put a transom in there but I figure the second step is to figure out what I'm doing about a fuel tank as that will determine the structure of my floor setup. I was thinking of one tank about 70 gallons or so. I talked to the guy that I usually use for this stuff. He is an amazing fabricator and making a tank like this is like asking the Paul senior to make me a moped. His original thought was to make the tank with .25" aluminum. Right off the bat I thought that seemed aggressive but he said hes seen lesser tanks crack. He said with that thickness and a few baffles that it would last forever. I assume there are prefab tanks I could use. He asked if I could find some specs as far as thickness etc. I'd like to use him to build me a tank (unless it's twice the cost) because he can make it exactly how I want it and hes a good friend as well. So I suppose my question is, what are the specs of a tank this size? I figured if it was properly bedded in some foam and properly attached that .25" aluminum may be a bit overkill. Any input? Thanks everyone. Looking forward to getting this boat moving.

[FishStretcher]

I think mine is 3/16", but I have a 20 gallon tank under the console in my boat. It had a 45 gallon, which I also think was 3/16" thick at ~24" x 60" x 8" tall. It sat between the two big stringers in a potter hull and stopped under the console. That leaves room for a "head" in a 20 foot Master Angler.

Pics of my 45 gallon removal from my 20 footer here:

http://s1119.photobucket.com/profile...tretcher/index

With a small 4 stroke, I put the 20 gallon in it, I can't motor far enough to need more with a 100 HP 4 stroke. The boat had a 175 HP 2 stroke in it when I got it, and I think it probably had the same range with a 45 gallon tank.

[Normagain]

I had mine done in .190 aluminum which is 3/16". Mine is 72" X 23" X 10" and holds 68.8 gallons accounting for thickness of material if my calculator is correct. The floor is getting raised over two inches to accommodate the tank. Factory is 60" X 24" X 8", 1/8" thick. The place I had mine fabricated, American Tanks does most tanks in 3/16". It is plenty thick in my opinion, very sturdy and a bit heavy. 1/4" would weigh quite a bit more! Here are a few pictures of mine, one is a dry fit to make sure my floor will be high enough to clear everything. I also used it to weigh down 1/4 inch Coosa board when I epoxied that in place in order to get a nice even surface. The factory tank had three thin neoprene strips running the length of the tank. My place welded on three aluminum strips going the other direction and will have neoprene stuck to them with contact cement. Foaming in is not the best way to do it if you want it to last. The metal needs to be able to breath so water does not collect and corrode the tank. The reason I used 23" width by the way is I am sistering 3/4 marine ply all along the stringer sides where the tank is. Epoxied in place this should give the screws a good bite to hold the tank steady.

[Old'sCool]

Ditto on most of that...Sunshine in Fla made my 118 gal., same install except epoxy coated first.

[Basketcase]

That's exactly what I needed, Normagain. Thank you. I'll pass that on to my fabricator.

[Normagain]

Your very welcome. There are a lot of good threads here on building where I got many of my ideas but let me know if you want pics of how I'm doing mine. One of these days I'll post something up here, just waiting for our 100 degree plus days to go away so I can bet back on it!

One thing I learned, if you do the rubber strip thing, use Neoprene. It is one of the easiest to find anyway, some rubbers will react with the aluminum apparently and cause corrosion.