Fuel Tank Is Tanking

By: Frank Lanier

QuestionI am restoring a 1993 Wilson fishing boat. It is 26 feet long and 8 feet wide. I have started to smell gas in the cabin, so I figure I need to replace the fuel tank. It is aluminum, and as far as I know, it is the original and has been under the floor for 20 years. I think it may be leaking. What is the best material to use for a gasoline gas tank? Aluminum, stainless or some form of poly? 


Smelling gasoline is rarely a good thing, but don’t condemn the tank just yet. Unless there are obvious leaks in the tank, the first thing I’d check for would be deteriorated hoses — tank-fill hose, vent hose and fuel lines to the engine. All hose has a limited life span (seven to 10 years is commonly advertised for fuel-system hoses), so if yours are original, they’re well overdue for replacement and may show signs of deterioration and leaking. If the hoses look good, the next step would be to have the tank pressure tested, which will show if there are any leaks.

If there are leaks, the tank will probably have to be pulled for further inspection, which is easier said than done if the decks have to be cut to gain access. Depending on the circumstances (construction material, nature of damage, etc.), repair may be an option, but once the old tank is removed, replacing it will likely be the best choice. There are a number of materials that can be used, but each has its own set of pros and cons. Since your current aluminum tank lasted almost 20 years, I’d strongly consider sticking with aluminum. 

Aluminum is a popular fuel tank material, but when the tanks are located below cockpit decks on open-type fishing boats, they can corrode if they are not installed correctly. This is particularly true if they are “foamed” into place during construction, as the foam often retains moisture, or if the tank bottom has inadequate clearance to stay clear of the bilge water. Boats with removable deck panels are great for accessing and inspecting fuel tanks, but these panels should be pulled every five to seven years, both to inspect the tanks and renew the caulking (to prevent leaks onto the tank).

The American Boat and Yacht Council “H-24 Gasoline Fuel Systems” provides a wealth of information on tanks and their associated components.


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