Fuel tanks

[Pieman]

Morning all newly joined as a sailor to power boating. Recently purchased fountaine pajot powercat in Darwin and motored to Hervey Bay.discovered one fuel tank slowly leaking , big problem. Made of aluminium and not removable without major surgery. Any thoughts, help very much appreciated cheers

[Lepke]

If there's an access port or you can cut one in, there are many tank coatings that will stop leaks and protect the tank from corrosion. It might be possible to drain the tank, clean any fuel residue off the bottom and coat the outside, but that's only a temporary solution. Some people fiberglass the entire tank.

[Uncle Bob]

Originally Posted by Lepke

If there's an access port or you can cut one in, there are many tank coatings that will stop leaks and protect the tank from corrosion. It might be possible to drain the tank, clean any fuel residue off the bottom and coat the outside, but that's only a temporary solution. Some people fiberglass the entire tank.

This
I would look to the aviation industry and find what coatings are used there.

[AndyEss]

Are you positive it’s the tank that is leaking? Fittings and/or hoses are usually far more likely to be the source of leaks. Check and eliminate the possibility of these leaking first before tackling the tank.

[Pieman]

Thanks for the prompt replies. All tank fittings are thru the top and do not leak as far as can ascertain. Now have four access holes in top of tank . Am looking into coatings but having some difficulty with information as to what precisely they do .has anyone had experience with these . I am loathe to start cutting tanks up apart from the expense it appears a difficult and dangerous job

[Chotu]

How about a fuel bladder in the tank?

[Tin Tin]

Probably pin hole leaks in the base of the tank or at a weld. This happens when tanks are left for long periods and condensation forms and puddles in base, then the anaerobic algae gets into it and you get a black mess and corroded bottoms. Epoxy glass coatings on the outside will work for a while, but fiberglass and aluminum expand at different rates and the repair may split. Because they are diesel tanks once emptied they are not as explosive as gasoline. You could fill with water and drain again. One solution may be to cut the lid off and insert a fuel bladder, these come in all grades, shapes and sizes, it might carry slightly less fuel but should last a long time, probably longer than alloy. My two bobs worth.

[Lepke]

This sealant works with diesel. You need to get all the diesel out and clean the tank well with a strong soap solution. Maybe more than once.
https://www.aircraftspruce.com/pages...ts/al13063.php

[rsn48]

Aluminum tanks have a lifespan, you can google how long they last but the short answer is, not as long as you think. So for some, they will seem to go on forever, others will be cursing at them much sooner than they thought they would. If you are keeping the boat for the long haul, then replace them, if only for a short time, then repair them or it.

I have a gas engine and the tanks in my boat were 50 years old. I googled how long aluminum tanks should last and as you can guess, it was well before 50 years. So I decided to have them removed by my refit guy. He was being nice and told me not to replace them to save money. I prevailed as I knew they would have to come out sooner than later. The tanks appeared to have no problems. Once out we discovered, over time, a very slow almost microscopic leak. The one tank had 50 gallons of gas in it and when it was removed, stored in the refit yard. A year latter the tank was empty still sitting in the yard.

[sailormed]

”The one tank had 50 gallons of gas in it and when it was removed, stored in the refit yard. A year latter the tank was empty still sitting in the yard.”

There could also be another explanation for the disappearence of the fuel. 50 gallons of fuel has a certain value.

[tkeithlu]

For diesel, I vote for cleaning and then coating the inside with flexible goo. For gasoline, replace it. The clean and goo is time consuming but not expensive. Replacing is time consuming and very expensive. If you try and fail, you have some diesel in the bottom of your boat. It smells bad. If you try and fail with gasoline, it smells bad and is explosive.

[rsn48]

Disappearing fuel could have been stolen, but not where the tank was. We found a very small leak in one of the corners, a common area for leaks in aluminum tanks. I replaced mine with poly tanks, it gave me the opportunity to extend my cruising range as I increased the size of the tanks, 80 gallons versus 50 gallons (times 2).

[gonesail]

depends on your definition of major surgery. I personally would not be satisfied with trying to patch an aluminum tank in place.