# Making a fuel tank with G10 fiberglass board



## lizardheadone (Oct 9, 2007)

Has anyone fabricated a diesel fuel tank from G10 fiberglass/epoxy board? I was just wondering if you could build a succesful fuel tank by fiberglass taping G10 board together. What ya think?


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## mitiempo (Sep 19, 2008)

It could be done, but g10 isn't exactly inexpensive. Have you priced it out yet? How big a tank? You probably wouldn't save much over having one professionally made in stainless and it's a bit of work. If you want to build one use plywood and epoxy it well inside and out - a lot less expensive. Here's a link to a pdf from West epoxy detailing how to go about it.
http://www.epoxyworks.com/18/pdf/tanks.pdf
Brian


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## jrd22 (Nov 14, 2000)

Or just make up a mold and make a glass box with no top, then make a flat board and glass it on to make the top. Making fiberglas boards is easy and fast, as long as you're not too fussy about how they look


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## mitiempo (Sep 19, 2008)

jrd22
Why go to the trouble of making a mold and using a lot of glass and epoxy? If you build it of thin plywood you'll use a lot less epoxy and cloth for the same result.


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## tommays (Sep 9, 2008)

Fuel tanks have a certification tag and it will be a sticky insurance area if you DIY one as there is a LOT of Conforms U.S. Coast Guard regulations


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## mitiempo (Sep 19, 2008)

tommays
Tanks purchased from a tank manufacturer do but custom tanks do not have certification tags. It is a long and expensive process to certify a tank. If they all had to be certified there would be no custom tanks.


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## tommays (Sep 9, 2008)

Yes

But the builder is certified at least in the US 

Just like pressure vessels like air tanks have to 100% certified


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## mitiempo (Sep 19, 2008)

Here is a link to a pdf explaining how to build a fuel tank from fibreglass. http://www.practical-sailor.com/newspics/charts/8912byofiberglasstanks.pdf
In Canada I know of no regulation either preventing you from building a fuel tank or requirements for the builder of a custom tank to either have it certified or in fact be certified himself. I have owned 3 boats over the years that I have had custom tanks made for and the issue has never come up. All tanks were stainless steel and pressure tested to 5 psi. I've never been asked by an insurance company for any fuel tank certification. I do prefer stainless steel to other materials. I tried to find Canadian pleasure craft fuel tank regulations on the web but all I found was a Canadian Government site that referenced ABYC.


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## jrd22 (Nov 14, 2000)

Mitiemp- it would be easier to use plywood and as long as it was saturated with epoxy I don't see why it wouldn't work, but all glass would eliminate any worry about the wood becoming saturated with diesel at some point or the plywood dry rotting. Our tanks are also SS and so far so good, but all metal tanks will probably leak or fail at some point. Integral fiberglas tanks would seem to be the all round best route but difficult to retrofit.


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## mitiempo (Sep 19, 2008)

jrd
I replaced a 32 year old steel tank this past winter. In my boat the tank (about 14 gallons) was hung below the cockpit with nylon straps. The original tank was rusted on top (but not leaking) because the fuel fill was in the cockpit sole and water leaked around the fill fitting onto the tank top. I think that is the wrong place for a fuel fill so it is now on the side deck on a slightly raised base. The new stainless tank is not held in place with straps but has two vertical strips welded on top for its length and is bolted to two structural beams underneath the cockpit sole. The underside of the tank is clear so the tank is not able to sit in water as a tank often is. I expect to get at least 32 years use out of this tank and as I'm 57 now that should be long enough. 
As far as a glass tank I came across an article about building fibreglass tanks http://www.practical-sailor.com/newspics/charts/8912byofiberglasstanks.pdf
that detailed a case of a balsa cored fibreglass tank that was in a fire. The details are below. I would think that a plywood core would act the same way and be durable and leakproof as long as the outer and inner skins were thick enough. The tank in question had 1/8" thick skins which seems a bit light to me.


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## lizardheadone (Oct 9, 2007)

Thanks for the replys. It is an integral frp tank that I need replacing. I was also thinking of cutting the surge baffles out of the existing tank and laying up a new tank within the old one, then replacing the old surge baffles and taping them in place. Think this could work? I don't think I would have to worry too much about the bond between the two tanks as I would if it were just a patch. It could prove to be a very uncomfortable job in a very tight area.


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## mitiempo (Sep 19, 2008)

Lizardheadone
While I think it would work, contamimation from the existing diesel could be an issue. Do you have good access to the top of the tank? If I were to do this I would drain and the old tank, cut the baffles out, and clean it until you could eat out of it. I would build the new tank of fibreglass sheet, either g10 you buy or sheets you lay up yourself. It's not hard to do, just lay up a few layers of 1708 biaxial on a flat surface covered with heavy plastic so it doesn't stick. The sheets only have to be thick enough to not be flimsy at this stage. Then I would cut the ends and sides of the new tank to be a snug fit inside the old tank. Place them inside in their respective places and just tack them together at the corners taking care to not bond to the old tank. If you place plastic at the corners of the tank between the old tank and the new panels this will help. After this has set remove the 4 sides, now 1 piece from the old tank. This gives you the shape and you are able to work in a better place than the bilge. Cut bottom to fit and finish the tank, glassing the seams very well and building up thickness as necessary. I would not use the old baffles as they have probably absorbed enough diesel over the years that you would never get a good bond. Then take the tank and get it pressure tested. I would also build it with cleanouts over each baffled section. When you're finished and have checked for fit in the old tank use thickened epoxy to bond the new tank to the old. Even after cleaning this may not bond well but the main thing is to fill any gaps between the two so the new tank can't move in any direction. Then lay up a few layers of biax overlapping the top of the new tank and onto the hull around all sides to finish the attachment. It should work well but it's a long process and when you're done you may wish you had a custom stainless tank made.


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