Fortunately, most boat owners won't come into this issue unless they've had their boat for a long time or are looking at buying an older yacht. If properly fitted and maintained, most fuel tanks should last 12-15 years. Obviously, the materials utilized, like steel, aluminum, fiberglass, or plastic, will have a role, but moisture and humidity also play a role. If your gasoline tank is properly aired and cleaned regularly, it could last up to 15 years.