A strong solvent, ethanol has been known to degrade marine fuel systems, damage engines, add safety concerns and lead to expensive repair bills. "When filling up at gas stations, boaters normally pull up to the pump and fill up the tow vehicle first, then put the same fuel nozzle into the boat," said BoatUS Director of Damage Avoidance Bob Adriance. "If that happens with E15, it could be a big mistake."
The EPA will put, at some point in the future, a warning on pumps carrying E15. The warning will be a small label with the exact wording yet to determined.
All of this means when E15 starts to appear at gasoline station pumps, boaters must heed the warning and shouldn't even think about using E15 in a boat. Here are some reasons:
• Going "lean" isn't good: In addition to hydrogen and carbon found in regular gasoline, ethanol also contains oxygen, which means less air (conversely, more fuel) is required for combustion. The term "enleanment" is used to describe what can happen when there is too much air and not enough fuel. While most cars and trucks on the road today have closed-loop systems that can adjust to prevent enleanment, most boats have open-loop systems which do not, adding a greater risk of heat-related damage to a boat's engine with E15.
• Compatibility questions: Many components on a boat come in contact with ethanol-laden gasoline, including fuel lines, fuel tanks, fuel pumps, fuel injectors, carburetors, pressure regulators, valves, o-rings and gaskets. The compatibility of these components with any blend greater than E10 is unknown. The failure of only one of these components in an engine could lead to failure, or worse, fire or explosion.
• A "good" thing isn't what it seems: Phase separation happens when gasoline becomes over-saturated with water, leading the water/ethanol mixture to separate from the gasoline and fall to the bottom of the tank (where the engine's fuel pickup is located). However, since ethanol absorbs water more readily than gasoline, and it burns harmlessly through the engine, adding more ethanol to gas will decrease the chance for phase separation. That would seem to be beneficial -- but it's not. As the amount of water increases in ethanol, the mixture also becomes more acidic, increasing the potential to corrode metal, including aluminum fuel tanks.
Boat owners also should keep in mind that once gas has phase separated, the only remedy is to completely empty the tank.
Although BoatUS believes fuel additives in general are a good thing, it hasn't seen evidence of any additive being able to restore phase-separated gas back to its original state.
• Your warranty won't help you: Marine engines are only warranted for use with up to 10 percent (E10) ethanol.
So what can boat owners do, with most pumps using E10 and many soon to convert to E15?
David Meeler, product information manager for Yamaha. said the key preventative step outboard owners should take is installing a water/fuel-separating filter between the fuel tank and the engine, if one isn't already in place, and purchasing a 10-micron cartridge for the filter, rather than the traditional 28-micron cartridge. The finer cartridge will do a better job of removing water and impurities.
"As long as you've got a good 10-micron filter, your boat should be OK," Meeler said. "Yamaha came out with a new 10-micron filter 6 years ago in specific response to problems with ethanol. It works with the on-engine filters we use. It's flow-rated and designed particularly to counteract the damaging effcts of ethanol."
The Yamaha 10-micron filter goes inside a spin-on type canister that works similar to an oil filter in an automobile.
"It's got a little mounting head to screw into a bulkhead in the bilge, where you'd typically put such a device," Meeler said. "All you do is cut the fuel line and run (the gasoline line) into the filter and out to the engine."
The device filters debris from fuel tanks and also features a water-entrapment system. Meeler said Yamaha's filtering device could be used with any marine engine.
"Water (that may have gathered in a fuel tank) is safely drained away, too," he said. "(The 10-micron filter) is the primary line of defense for problems created by ethanol in marine fuel."
However, some filters work better than others. Meeler said the key characteristic of a fuel filter a boat owner should know is its efficiency rating.
"A lot of (filters) don't have efficiency ratings," he said. "Some say they're 10-micron (filters) but trap only 25 percent (of debris and water)."
However, Meeler said Yamaha's fuel-filter proficiency rating is 85 to 90 percent for an engine that burns 90 gallons of fuel per hour.
"The 28-micron filter is the old standard, but it's totally useless against ethanol (problems)," he said. "If you're using ethanol fuel, and you don't have a 10-micron filter on your boat with a high efficiency rating, your clock is ticking."
A boat's 10-micron fuel filter should be changed every six months or after 50 hours of engine operation, Meeler said.
