Aluminum versus stainless steel fuel tanks

[gghanger]

Every one says aluminum like it is one product
... What is it 6061 or 5086... Makes a big difference... 5086 can lay in the ocean and never corrode... So which is it?

[kmacdonald]

Go with aluminum.

[jewt]

Had a monel fuel tank on my last Morgan and it is still good after 50 years!

jewt

[Cheechako]

Either may not be great. I have had both fail on boats I had. The Taiwan SS in the bilge failed by 7 years. Big time hole the size of a pencil eraser. I replaced it with Titanium. But was fortunate to have access to it reasonable and a good welder to do it.
Both Aluminum leaked pin holes after maybe 10 years. Where metal tanks fail is often where they sit on something, water stays in the gap.
Plastic is the way to go. or sure.. Monel!

[coopec43]

Originally Posted by Cheechako

Both Aluminum leaked pin holes after maybe 10 years. Where metal tanks fail is often where they sit on something, water stays in the gap.
Plastic is the way to go. or sure.. Monel!

My tanks are marine grade aluminum but I have glued plastic strips to the tank where they sit on the "floors" (ribs?)

[hpeer]

In my wanderings I have come across a 2 part epoxy that is used to seal tanks in aircraft wings. It is marketed in the marine world by the Boat Life caulk folks, but can be had cheaper and in more formats from the aviation industry.

I’ve no idea WHY you are replacing your tanks, or how far along, but this stuff is a honest to goodness repair product. So maybe don’t replace, but use this on the inside as a repair of your leaks. The tanks must be clean obviously.

There are 2 types, pourable and heavy. The heavy will seal up to. 1/4” vertical crack. And they do have a shelf life, don’t keep forever.

This is the heavy

Life-Calk Two-Part Sealant Type H (Heavy) 750ml - BoatLIFE

[Fore and Aft]

I have surveyed a yacht that had aluminium fuel tanks full of pin holes. The owner removed them , covered them. With two layers of chop strand mat and polyester resin and then painted with flo coat. He then put them back in the yacht. They looked like new and never gave anymore trouble.
Cheers

[svfinlandia]

Originally Posted by coopec43

I wonder why you are replacing a ss tank. Maybe it work hardened because of continual flexing as the fuel sloshed around the tank and that started a leak?

Hurricane Florence roared through North Carolina and the storm surge in my marina lifted the boat up and dropped it down on a piling, which cracked a weld on the back of the stainless tank. The weld was inaccessible and the tank was so large that it had to be removed by cutting it up to get it out.
I had intended to replace the tank with two smaller stainless tanks that we could fit back into the original space, but the yard insisted that aluminum would be a better replacement than stainless.

Al, S/V Finlandia

[svfinlandia]

Originally Posted by nhschneider

I remember reading that ABYC only approves of stainless steel fuel tanks if they’re cylindrical in shape with rounded ends. That being said, when our 90-gallon starboard stainless steel fuel tank developed a leak after being in service for 20 years, we replaced both port and starboard tanks with stainless steel ones. I would have preferred going with roto-molded ones but couldn’t find the size I needed. Fair winds and calm seas.

Please correct me if I am wrong, but it is my understanding that ABYC only applies to manufacturer's and new construction.
As it is my old 1983 (and not a commercial) boat, should I not be able to (at my own risk and consequences) to put any kind of tank in it that I wish?

Al, S/V Finlandia

[svfinlandia]

Originally Posted by gghanger

Every one says aluminum like it is one product
... What is it 6061 or 5086... Makes a big difference... 5086 can lay in the ocean and never corrode... So which is it?

Looking at the comparison of the two, I don't see that it would make very much, if any, difference for a sailboat diesel fuel tank. See comparison chart at:
https://www.makeitfrom.com/compare/5...61-T6-Aluminum

Al, S/V Finlandia

[svfinlandia]

An edit to my last missive: I meant to say that it should NOT make very much difference.
Sorry for leaving out the word not.

Al, S/V Finlandia

[coopec43]

Originally Posted by svfinlandia

Please correct me if I am wrong, but it is my understanding that ABYC only applies to manufacturer's and new construction.
As it is my old 1983 (and not a commercial) boat, should I not be able to (at my own risk and consequences) to put any kind of tank in it that I wish?

Al, S/V Finlandia

Insurance industry could object. Regulatory Authorities may object. Boat marinas may not allow the boat into the marina unless it is up to a certain standard....

[dkenny64]

might be a crazy thought..
metal.. galvanic corrosion...can apply to all metals..

plastic..polyethenyne (sp) are used in many cars and truck...
fiberglass - for diesel.. not a problem so far..
my boat is crica 1986..not that old..but no tank issues.. if it a gas boat
since enthanol came out..different issue..


fiberglass would be better if the fuel is diesel..poly if fuel was gasoline(petrol)


-dkenny64

[Cheechako]

Originally Posted by svfinlandia

Please correct me if I am wrong, but it is my understanding that ABYC only applies to manufacturer's and new construction.
As it is my old 1983 (and not a commercial) boat, should I not be able to (at my own risk and consequences) to put any kind of tank in it that I wish?

Al, S/V Finlandia

ABYC is voluntary. It's not a gov't agency.

[hpeer]

Originally Posted by Cheechako

ABYC is voluntary. It's not a gov't agency.

Muntil the insurance company adopts those standards. Then it’s mandatory, at least for that insurance company.

So YOU must use tinned Wife, but Yanmar is not required to do so. FBS.