View Full Version : E-10 Ethanol Fuel And Winter Boat Layup

10-30-2006, 12:15 PM
Hey all,
I got this from my boat insurance company today.

NEWS From BoatU.S.
Boat Owners Association of The United States
880 S. Pickett St., Alexandria, VA 22304
BoatU.S. News Room at http://www.BoatUS.com/news/releases.asp

Press Contact: Scott Croft, 703-461-2864, [email protected]
Date: October 23, 2006


This spring and with little prior notice, recreational boaters in most parts of the country were introduced to gasoline containing higher concentrations of ethanol, a corn-based additive that replaced a known carcinogen, MTBE. The new fuel, dubbed "E-10" for its 10% ethanol content, unfortunately has the ability to attract greater amounts of water and "phase separate", or form two separate solutions in the gas tank, usually over a long period of time. Once this happens, the engine won't run and internal damage could occur. With the lengthy winter lay up period upon us, many boaters are asking how they should store their boat over the winter to prevent fuel problems next year. The BoatU.S. damage prevention newsletter, Seaworthy, tackles the problem in its October issue and has these recommendations:

Once phase separation occurs in E-10 gasoline, additives and water separators can't help. The only remedy is to have the gas and ethanol/water professionally removed from the tank.

With any fuel that sits in a tank for a long time, it's important to add a stabilizer. But understand that stabilizers do not prevent phase separation.

E-10 has been a fact of life in certain areas of the Midwest for over a decade and there have been relatively few problems. The best practical recommendation learned from marina operators in the region is to top off a boat's fuel tanks to about 95% full, leaving room for expansion. A tank that is almost full limits the flow of air into and out of the vent, which reduces the chance of condensation adding water to the fuel. Draining fuel tanks of E-10 gas, while completely eliminating any chances of phase separation, is potentially dangerous and an impractical solution.

Whether you believe your boat's fuel tanks are half full or half empty, leaving a tank partially filled is a bad move. A Midwest marina owner confirmed that phase separation problems typically occurred when boats were stored over the winter with tanks only one quarter to one-half full. In the summer, infrequently used boats with partially filled tanks are also prone to phase separation.

Never try to plug up a fuel tank vent to prevent moist air from entering a tank. Without room to expand, the additional pressure could rupture fuel system components.

11-05-2006, 08:12 AM
yah, I've heard some nasty things about ethonal in the fuel.

I bought some of this stuff at West Marine, not sure if it will help any, but for a few bucks, it was worth trying to prevent a hassle in the Spring!!


Article about it.....

11-05-2006, 08:52 AM
I agree that boats should be stored with a full fuel tank to prevent condensation, but the problem of phase separation in E10 is overblown in that article. The fact that alcohol attracts water is offset by the fact that gasoline with alcohol in it will hold much more water in suspension before phase separation occurs. Phase separation can occur in regular gasoline too.

I confess I laughed when I saw the "enzymatic" cleaning action of that additive. What a great marketing scheme :)

11-06-2006, 09:15 AM
I figured a full fuel tank w/ stabil should be good enough..... but.....

11-06-2006, 09:26 AM
I figured a full fuel tank w/ stabil should be good enough..... but.....
It is, IMHO. Personally, I wouldn't worry about phase separation. That argument was an old one trotted out by folks who were vehemently anti-ethanol for non-highway vehicles, especially boats. It's proven not to be an issue. I was one of those phase-separation, anti-ethanol people until I actually looked into the chemistry of it. I still don't use ethanol in my boats, but that's only because non-oxygenated premium is readily available to me and delivered to my home tank at pump price. If I couldn't get that, I'd be fine with E10 although I would put a couple of water-absorbers in my storage tank since it can sit partially full for weeks at a time.

11-06-2006, 09:27 AM
I figured a full fuel tank w/ stabil should be good enough

Thats all i do, and am not worried about it.