Fuel Tank Questions

[triumph34]

We are in the process of rebuilding the deck and cabin of our boat and we are trying to figure out the install of new fuel tanks. We are going to install 2 tanks each at about 90 or 100 gallon. Can anyone tell me if it is necessary to use aluminum or can I use stainless steel fuel tanks? Also, if anyone has fuel tanks of this size or know where I can get some, let me know. Thanks for the help.

[tom28571]

I'd consider stainless as the king of custom fuel tanks. I don't know how aluminum fares with the new ethanol fuels but many have had problems with aluminum in the past. Personally, I would choose plastic if the standard sizes and configurations available would fit. Molders of plastic tanks I have contacted will not sell in quantities of one. Most probably they don't stock them and must set up molds for individual orders so it's not profitable to make only a few.

[triumph34]

What about just steel? Not stainless but a steel tank and then paint the outside with epoxy paint for corrosion protection.

[rasorinc]

check out these guys. composit tanks
http://www.incaproducts.com/site/why_plastic.aspx

[Submarine Tom]

Triumph34,

I researched this decision thoroughly when I was tanking my houseboat

and decided on five, plastic, pre-fab'ed, 10 gallon tanks.

I realize your application is completely different.

My point is, to fit the space and be cost effective, this worked really well for me.

Good luck, Tom

P.S. Don't forget, unless you keep steel tanks topped up all the time, you're leaving yourself open to corrosion inside the tank from condensation.

[marshmat]

Any kind of metal tank in a bilge space will be vulnerable to corrosion. The question is, can the tank be built and installed in such a way that corrosion will not pose problems during the expected service life of the boat? Although it's not uncommon for a good metal tank to last 20+ years, it's also not uncommon for an average to mediocre one- either aluminum or stainless- to be toast in six or seven years. You really have to trust the welding shop to use the right grades and thicknesses, and to have a good, effective QA program.

Steel is cheap enough that you can compensate for corrosion with extra thickness and a good paint system; I see no reason to reject it out of hand just because Al and SS are more popular.

A custom fibreglass tank is probably too much work/money, but surely you ought to be able to find stock cross-linked polyethylene tanks in a suitable size? It's very rare to hear of cross-linked polyethylene fuel tanks breaking, dissolving or wearing out.

[FAST FRED]

A plastic tank today has all the advantages , except one , rapid instalation.

The plastic tank will have to be installed , filled with fuel for a couple of days (they expand) and then foamed in place.

Unless you have the big bucks for the KING of tanks , Monel, plastic is todays "best".

FF

[Commuter Boats]

I've never seen what I considered to be adequate baffles in a plastic tank, most have none.

[PAR]

Adequate baffles in a 50 gallon plastic tank, is five 10 gallon tanks in a row.

[FAST FRED]

While they don't need to be quite that small (10G) tall narrow tanks can easily be combined to most any tank size required.

Although the valving (and fuel management) might be more complex an advantage of actually emptying tanks would cut down on condensation, and bug growth.

A simple transfer to a Day tank might even allow gravity feed to the engines , allowing fuel leaks to be easily found, air leaks can be a bugger in suction feed systems.

Many cruisers have huge tanks where the fuel rots month after month.

Only filling the needed tanks before a voyage might have big maint advantages for some cruisers.

FF

[SamSam]

Originally Posted by triumph34

We are in the process of rebuilding the deck and cabin of our boat and we are trying to figure out the install of new fuel tanks. We are going to install 2 tanks each at about 90 or 100 gallon. Can anyone tell me if it is necessary to use aluminum or can I use stainless steel fuel tanks? Also, if anyone has fuel tanks of this size or know where I can get some, let me know. Thanks for the help.

From the ABYC;

Q. What are the limitations for the use of stainless steel in fuel tank applications?
A. Stainless steel can be used for both gasoline and diesel fuel tanks. However, for gasoline tanks, the tank cannot be any larger than 20 gallons and it must be cylindrical with domed ends. There are no restrictions on size for diesel tanks.

From somewhere else;

Stainless Steel fuel tanks

The UL report indicates that some boat owners chose stainless steel as the material for replacement fuel tanks, since this material is obviously "stronger" than aluminum; however, it is also susceptible to pitting and crevice corrosion in the marine environment, although at a different rate than aluminum. Stainless steel is also susceptible to stress-corrosion cracking and is even more prone to that type of failure at weld areas.
Only the 316L stainless steel alloy with a specified minimum wall thickness of 0.031 inches is considered suitable for use in the construction of marine fuel tanks. American Boat and Yacht Council standards ANSI/ABYC H-24, ABYC H-33, and ANSI/NFPA 302 all require stainless steel fuel tanks to be less than 20 gallons in capacity and cylindrical with domed heads to limit the wall stresses experienced in service.