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Ethanol and winter storage

Winter is coming, and for those who store their boats for the season that poses a problem: How do you store the ethanol-laced gasoline in your boat’s built-in fuel tank?

Winter is coming, and for those who store their boats for the season that poses a problem: How do you store the ethanol-laced gasoline in your boat’s built-in fuel tank?

Opinions vary as to whether to store tanks empty or mostly empty, or whether to store them around 95 percent full.

The theoretical benefits of empty or mostly empty tanks, according to some experts, is that if there’s no ethanol in the tank it can’t absorb water, with the resulting possibility of phase separation. And it can’t dissolve old deposits in the tank. The theoretical benefits of a full tank, according to some experts, is that there’s less likelihood of moisture forming in the tank from condensation and that a topped-off tank minimizes the highly explosive fumes that can remain in an empty tank. (The National Fire Protection Association calls for tanks to be topped off to minimize explosive vapors.)

Bob Adriance is the editor of Seaworthy (BoatU.S.’s insurance and damage avoidance magazine) and author of the book “Seaworthy” (McGraw Hill/International Marine). A big part of his job is studying and documenting boaters’ problems and how to avoid them, using insurance reports and independent studies. In an article he wrote for Seaworthy (reprinted in the September 2007 issue of BoatU.S. magazine), he concluded, after interviews with various sources, that the best action is to use your boat regularly, store it with gas tanks around 95 percent full (this allows for expansion), and use a carefully chosen stabilizer, following manufacturer’s instructions.

Adriance reported that he’s spoken with many experienced sources in the Midwest, where they’ve dealt with ethanol for at least a decade. Encouragingly, they say that once the ethanol introduction period has passed in a region, the problem won’t be as severe if these practices are followed and if good tank maintenance is observed.

Erik Klockars, technical consultant for Soundings and owner of Klockars Engine Works in Old Lyme, Conn., works on boats for five marinas in addition to his private clients. He says he personally winterizes at least 150 boats every year and supervises the winterizing of another 700 to 800. He saw a number of problems, such as phase separation and damaged engines, directly related to ethanol when docks in his area (Long Island Sound) began selling it.

Speaking to reports of fewer problems in the Midwest, Klockars says that there are far greater temperature fluctuations along the East Coast during winter and that this contributes significantly to condensation. He also notes that neither engine manufacturers, fuel refiners nor governmental agencies are taking the responsibility to definitively recommend the best solutions.

Theoretically the best solution would be to completely drain and clean your fuel tank for winter storage, says Klockars. But that’s not the real world. Klockars says that it’s virtually impossible to remove all the fuel — it costs from $5 to $9 per gallon to dispose of old gas — and fire marshals want to see tanks full because of the danger of explosion from fumes. Many marinas share the same concerns about explosions, particularly those with rack storage. He says that the next best thing is to store the boat with the tanks around 95 percent full — using the highest octane gas available to hopefully compensate for octane loss resulting from winter storage — and adding a good stabilizer.

Klockars also emphasizes treating the fuel within the engines for storage. He mixes his own proprietary “concoction,” which includes stabilizers and other chemicals, and runs it through the engine from a small tank. If you want to try this, he says, consider filling your fuel filter with high-test fuel, a stabilizer and additives, and running that through the engine. (Be aware of the possibility of explosion when working with gasoline if you don’t use the right equipment and follow safe procedures.)

In addition, he suggests that during the boating season it’s best to use your boat as much as possible, filling up the tank when you leave the dock rather than when you return, and using appropriate additives, such as Star Tron and a good decarbonizer.

And diesel? It doesn’t contain ethanol, so those problems aren’t an issue. To prevent condensation, most experts agree that it’s best to store boats with diesel tanks around 95 percent full. When water sinks to the bottom of diesel, algae forms, and the byproduct is a black tar-like material that can clog filters, pumps and injectors, not to mention impair combustion, thus becoming more harmful to the environment.

Remember, if you plan to store your boat ashore with the tanks nearly full, the boat must be hauled and blocked in such a way that the weight of the fuel won’t damage the boat, and the boat must be built to handle this.