http://megayachtnews.com/Archives/July-2007/1749.html
Most mariners know that excess fuel emissions are dangerous to the long-term health of the planet. Recently, however, MTBE, the additive used to reduce emissions, was found to cause water pollution. As a result, MTBE is gradually being eliminated across the United States.
Taking its place is ethanol, a grain alcohol blended with conventional gasoline in a mixture of 10 percent ethanol to 90 percent gasoline, hence the term E10. Normally, the story would end here, with the problem solved.
Unfortunately, ethanol raises several serious problems that range from phase separation (ethanol bonds to water and the mixture falls to the bottom of the tank as a separate layer where it can find its way into the engine) to the sudden release of sludge build-up (which results in clogged filters and injectors). The situation is exacerbated by boats that sit idle, such as the third tender that gets minimal use or the onboard fuel storage tank that refills the tenders and water toys.
"Most boat owners are expecting problems," said David Brown, owner of Thompson Marine in Egg Harbor Township, N.J. "I dont think anybody really knows anything firm yet, and thats kind of the issue. Were not sure what to expect. We had a problem long ago, in the late 70s and early 80s when they tried ethanol before, with fuel lines and rubber hoses breaking down, so theres some concern we could see the same thing this time. Theres also an issue with the ethanol mixing with water and fouling up the engine."
Unlike previous incarnations of ethanol fuels, E10 fuel does not. While pure ethanol can indeed ruin rubber hoses, the 10 percent ethanol that is in E10 gas is a safe amount where hoses are concerned. As far as the tanks go, however, a certain type of fiberglass is vulnerable. How do you know if you have such a tank? Most people will probably already now. The majority of these tanks are on luxury vessels built in the 1960s, 70s and 80s, when these fiberglass tanks were considered the best material available. Boats built after the 1980s dont usually have a problem because the fiberglass resin was changed.
The overall news is good, that with intelligent fuel management, boat owners and crew can make E10 fuel work well despite its shortcomings. The availability of E10 fuel is growing along the U.S. East Coast, particularly in the central Atlantic states or points north.
The problems
The major downside to E10 gas is that the alcohol content attracts moisture. The alcohol attracts and joins with the moisture in the air to create larger amounts of water in the fuel tank than had occurred with MTBE blends.
Water in E10 fuel is a concern as far away as Hawaii, which became an E10 state on April 2. Gas station and marina owners across the state had to make sure that fuel storage tanks didnt have any water in them, install new ethanol-ready filters at the pumps and make sure the tanks are clean, said Maria Tome, an engineer with the state Department of Business, Economic Development and Tourism.
"A lot of older tanks were replaced recently, so most stations were ready," she said.
Still, gas-powered yacht owners are skeptical.
"Im not going to put it in the water as much this year," said Greg Masson of Maui, who owns a 40-foot Sea Ray. "I dont know what kind of damage the E10 fuel might do, so Im playing it safe until I see what happens to other yachts."
Water is heavier than gas so, along with the ethanol, it sinks to the bottom of the tank where a boats fuel pickup line is often located. Without an inline water-fuel separator, the water will go directly into the injectors or carburetor and can cause serious engine problems, including possible engine shutdown.
"Ethanol has become a huge, huge issue," said Robyn Ellis, owner of Ellis Marine in Leominster, Mass. "Weve had to service a lot of engines this year because of fuel separations."
In the case of a long-neglected tank, even a water-fuel separator may not be enough to deal with the accumulated water volume. Water buildup in the tank, in turn, drags down some of the blended alcohol with it.
This alcohol forms a portion of the overall gasoline octane rating. When octane is tinkered with, the consequences are a lowered octane rating and further reduced performance, rough running, and the potential for engine shutdown. (Automobiles fueling up with E10 dont notice this problem because most vehicles use the gasoline in their tanks every few days or every week.)
Alcohol is a natural solvent for the sludge, tars and other sediment found in marine tanks. While cleaning out the tank is normally good, it is not if the residue is released to the fuel pump. Usually, the fuel filter will trap the particles, but in some instances, the sludge has caused the gas to congeal into a gel, quickly clogging filters.
"Also, because of its solvent characteristics, ethanol can act as a quick cleaning agent, sweeping out any accumulated sludge in fuel tanks all at once," said Terry McBarnet, vice president of Maui Oil Co., a Chevron distributor. "So drivers (and fuel station and marina fuel dock owners) may have filters gucking up at first. So keep keeping a good eye on your fuel filters, especially if you have an older boat."
The solutions
Perhaps the easiest solution is adding a new additive to the fuel tank. Boaters have used alcohol-based or "dry gas" treatments successfully in the past to deal with water in the tank. But that was when gasoline was gasoline, not a mixture with ethanol.
Another solution is emulsifiers, but they disperse large particles of water throughout the gasoline, which can cause carbon buildup, poor engine performance and the formation of gum and varnish deposits. Additionally, emulsifiers require "violent shaking," something not easily achieved with a 25-foot center console fishing tender. One manufacturer recommends putting an air hose in the tank to agitate the mixture.
In the 1970s, General Motors and others did extensive experiments with emulsifiers to make cars more fuel efficient. In addition to severe performance problems, some of the worst effects were that the gas/water emulsifications ate the plating off internal components of fuel pumps and the carbon buildup was so bad engines had to be rebuilt every 20 hours. The vehicles were not driveable and tests were stopped. No oil company recommends emulsifiers; Chevron actually recommends de-emulsifiers.
Star Tron is a fuel additive that uses enzyme technology to prevent phase separation by de-ionizing the fuel, which means it neutralizes the electrical charges between water molecules. It is manufactured by Starbrite, a manufacturer of marine and automotive maintenance items, from anti-freeze and motor oil to brushes and polishes.
The de-ionization process prevents water molecules from forming into drops that then settle to the bottom of the tank and take the ethanol octane down with it. The octane rating is left in tact and the suspended water molecules can be burned right along with the gasoline portion of E10. It will also stabilize gas, allowing it to be stored for up to one year. Diesel fuel can be stabilized for up to two years.
When choosing a fuel additive, it is important to note that every fuel additive must be registered with the U.S. Environmental Protection Agency. StarTron is registered. Others, such as EZorb are not. For a complete listing, visit www.epa.gov/otaq/regs/fuels/additive/web-gas.htm
Switching to E10
Switching to E10 fuel for the first time will be of particular importance to yacht crews who would not normally empty the gasoline tank that fills the tenders before refilling it. The U.S. Coast Guard Chief of Auxiliary Surface Operations recommends that all vessel owners from superyachts to bowriders with gasoline tanks onboard wait to refuel with E10 until their tanks are nearly empty.
"Mixing these two types of fuel can cause the creation of a gel-like substance that can damage your engine and clog fuel filters," it says. "When making the switch to E10 stick to one supplier for your fuel. Some distributors have already made the switch and are selling the new E10 blend while others are still trying to sell off the MTBE fuel that they have left in their storage tanks. If your normal supplier has made the switch to E10 and you buy fuel from another vendor that hasnt switched over, you may find yourself with a tank full of mixed fuel."