Boaters, beware: Ethanol can eat at your gas tank

With the weather warming up, boating season is warming up across the state.

Yet boat owners in Tennessee should be wary of the sweeping blends of gasoline that are now being sold at retail stations, according to the Boat Owners Association of the United States.

Many stations now offer E10, which is a blend of 90 percent gasoline and 10 percent ethanol.

Ethanol is a solvent, and the use of E10 is more likely to have an adverse effect on a boat engine than an automobile engine because gasoline is often more sedentary in boats, said Bob Adriance, technical director for BoatUS.com.

"Boats sit for longer periods, and the problems that you have with ethanol typically are when they sit for longer periods,'' Adriance said.

When gasoline sits in a tank, residue can build up.

"You don't normally have those resins in a car tank because cars cycle through a tank of gasoline every week or two,'' Adriance said. "So they don't build up the resins that boats do."

Another potential problem with resin occurs with boats that have fiberglass fuel tanks. Over time, ethanol can dissolve the resin in fiberglass tanks. The resin bypasses fuel filters and can damage the motor.

"That resin forms a black goo that wrecks the engine,'' Adriance said.

Some later model fiberglass tanks have been built to withstand ethanol. As for other tanks, Adriance recommended they be replaced. Tanks made from stainless steel, aluminum or polyethylene can withstand ethanol.

Locating gasoline in Tennessee that does not contain ethanol can be difficult, said Betsy Woods, boating education director for the Tennessee Wildlife Resources Agency.

"Pretty soon … all gas is going to have at least 10 percent ethanol,'' Woods said. "Right now there are some that do not have ethanol in it at all and that would be my preference for my boat. Some pumps are marked stating they contain ethanol and some aren't. I would ask the person working at the station if they have ethanol in their gas."

Another problem with ethanol: it attracts moisture, which can result in water getting into the tank. Adriance said it's best to fill the gas tank to 95 percent of capacity after each use.

Some fuel hoses, especially those manufactured before the 1990s, are not compatible with ethanol. Boat owners should make sure all hoses are marked "J-1529 U.S. Coast Guard approved."

"If you don't have those hoses on your engine then I would say use regular gasoline or just update your hoses because chances are they're long overdue,'' Adriance said.