fuel tank materials

[scphantm]

i am in the process of building a 41 foot mainship style hull into a sort of aft cabin that i plan on living on. ive got a big question about the fuel system. originally i was planning on building the fuel tanks out of fiberglass but the local tampa newspaper just had an article a week or so ago saying that boaters are getting into more and more trouble with the gas blend they are selling in marinas now. its the 85/15 alcohol mix. basically the article said in boats if the fuel sits in the tank for more than 3 to 6 weeks depending on temperature the alcohol separates from the gasoline and is highly corrosive, to the point where it eats the aluminum, fiberglass resin, and rubber fuel lines in boats.

eating fuel lines, yea i can see that, i can solve that problem by using copper or stainless hard lines and flex points using nylon or viton line to solve that problem

my big problem is the tank itself. my installation requires some odd shapes so plastic i would have to have custom built, big $, aluminum i can bend and weld myself but if it eats it from the inside out that doesn't do much good, and if it eats fiberglass thats not an option. i was planning on using full epoxy resin so i wouldn't think it would it would eat it but ive been proven wrong before. but what about the aluminum, there has to be a coating of some kind i can put on the aluminum to protect it.

comments?

thanks guys

[rasorinc]

These people make custom plastic tanks of all types. You may be able to adapt to one of their many standard shapes.
http://www.incaproducts.com/site/why_plastic.aspx

[CaptGraham]

This information may be helpful...
http://www.admiraltymarinecoatings.com/fiberglass/fueltank/fueltank.html

Best regards,

Graham

[Willallison]

Unless there were good reason's to opt for something else, I'd go for HDPE tanks every time. They don't corrode, don't suffer from dissimilar metals drama's, can be made any shape you like and in my experience are no more expensive to have made than any other type of tank. They do tend to be quite heavy if well made and you have to be carefull that you don't strip the threads when adding fittings. It's also a good idea to allow for 2 - 3% expansion the 1st time you fill the tank too.
Beyond that, they are as close to the perfect tanks material as there is IMHO...

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scphantm

Nothing wrong with using ally for tanks. Coating is not necessary, just make sure you use marine grade ally. I've used bare ally tanks on endless different boats..