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Dangers Lurking in E10 Boat Fuel

Back in 2010, the U.S. Coast Guard Auxiliary warned boaters about the damage that ethanol-blended gasoline can produce on boat engines. Despite this warning and many others from boating organizations, boat engine manufacturers, and boat dealers, some boat owners are still unaware how ethanol-blended gasoline hurts their boats. Although ethanol gas reduces dependence on foreign oil, supports the agricultural industry, and produces three to four percent fewer greenhouse gas emissions, it also can attract water to a fuel tank, causing a sludge that can destroy an engine. Why is this problem pertinent to boats, but not to automobiles?

Ethanol Gas and Your Boat

The difference between using ethanol-blended gas in cars and boats is that individuals often use their cars more than they use their boats. This lack of use is hitting particularly hard in drought-stricken areas this year, according to some boat dealers. Depending upon the size of the boat motor, the damage caused by failing to use a boat that runs on ethanol-based fuel can tally into the thousands of dollars if that boat is not properly maintained.

Additionally, boat engines contain vented fuel systems that allow moisture to enter fuel tanks. When the alcohol in the E10 (10% alcohol) gas blend sits idle in an engine, it absorbs moisture from the atmosphere — in fact, it can absorb up to 50 times more water than non-alcohol gas. After sitting for a time (90 days or even less), the water and ethanol mix separates from the gas and sinks in the fuel tank (phase separation) to create a milky-brown substance that can cause boat engines to misfire.

Misfiring is just the first sign that something might be wrong. According to Fuel Testers, “Phase separation occurs in E10 gas, when only 0.5% water or 3.8 teaspoons water per gallon of fuel is absorbed.” Even if you’ve had your boat out every day this summer instead of laid up in dock, E10 gas can dissolve up to 6,000-7,000 parts per million (PPM) water at 70 degrees Fahrenheit. When this blend cools, the water and some of the ethanol become insoluble, creating problems from the get-go.

Since ethanol is a solvent, it also can soften rubber hose interiors, breaking pieces off that can clog the fuel system. If you own a boat with a fiberglass fuel tank, the ethanol can dissolve the resin that holds the material together. That material, also, can head into the engine. It can also dissolve plastic, rubber, and aluminum parts, dry out hoses, remove lubrication, and shrink or swell engine seals.

The best thing for you to do is to be aware of your manufacturer’s warranty for your boat and be aware of where you’re gassing up and what gas you’re using for your boat. If that warranty forbids using all ethanol and “gasahol” fuel and you use it anyway, you may end up being responsible for damages. Once E10 begins the phase separation in a tank, there’s little you can do to repair that damage, despite claims that you can repair phase separated fuel.

What Can You Do?

Even winterizing a boat that uses E10 can prove a nightmare for boat owners, because it’s rare that you can completely empty a fuel tank. If you can siphon the tank or pump it dry from the fuel line, you might get professionals to buff the interior of the tank to remove any loose particles that could clog the engine. Additionally, be aware that water-separating fuel filters can become clogged when using regular gas, let alone E10, so carry a few with you when you’re out on your boat.

Some states mandate E10 fuel, so there’s not much choice in the matter when it comes to fueling your boat in those states other than to purchase a boat motor that tolerates alcohol-based fuel. Other states still offer ethanol-free gasoline, which is a preferred choice for many boaters. Since hot weather accelerates deterioration, it’s not surprising to find marinas in the south that still carry the option for non-alcohol gasoline.

While some boat engines are compatible with E10 fuel, some manufacturers still warn about outboard fuel systems that can sustain damage from that fuel choice. The problems that arise usually come at the fuel station, when boat owners are distracted or tanks are not labeled correctly — in fact, the Marine Retailers Association of the Americas (MRAA) warns that many consumers fuel their boats when they fuel their cars, and confusion over mislabeling gas or lack of consumer awareness may end in destroying a boat engine.

The Environmental Protection Agency (EPA) has approved E15 (15% ethanol) for use for newer trucks and cars, but that use has been delayed because of multiple lawsuits from the marine, auto, and small engine industries, including MRAA. We don’t know of any boat engine that’s equipped to handle E15, but we also know that the EPA has not approved the sale of E15 at marinas. To reiterate:

  • Read your boat engine warranty so you know what fuel you need to use for your particular engine and boat.
  • Maintain your boat as well as you can to avoid any E10 fuel damage. This maintenance includes any additives you may need to keep the E10 fuel fully integrated and to reduce the fuel’s ability to absorb water and separate. Remember — if that fuel has separated already, no additives will repair the fuel itself. Empty the fuel tank, clean it out, and refill with fuel covered by your warranty.
  • Address your problems quickly, including replacing any fuel lines, gaskets, or any other worn or affected parts.
  • Always fuel your boat at a marina.
  • Use regular gasoline if you have that choice.

Finally, you might want to read your boat insurance policy again, because no two policies are the same. Don’t accept a policy that leaves you uncovered. Contact the ABA Boat Insurance Program about your boat insurance needs.

Source: Randy Troutman, United Marine Underwriters

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