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Ethanol - Is It Good For Your Boat?
May 29, 2011 6:54 PM | Tagged as Ethanol

Ethanol may not be a boater’s best friend!  

Ethanol is a term everyone in the country is becoming more and more familiar with each and every day. Although it is most popular in the midwest, it has become the additive of choice for gasoline. It  acts as an oxygenator and octane booster in fuel, taking the place of other additives that have been found to harm our environment. It is less popular on the east and west coasts where corn is not being grown extensively and few ethanol plants have been built. The prescribed amount of ethanol mixed with gasoline is 10%, but in California, the amount is only 5.6% due to the short supply. With new government rules looming, soon it may be hard to find any gasoline without ethanol. That means it could be at marina gas pumps - not ony at corner or highway stations. 

What does ethanol do? Ethanol helps to clean up a car engine’s exhaust by making it easier for the catalytic converter to do its thing. At a 10% blend, it doesn’t decrease mileage much, even though it has only 60% of the heating value of gasoline. Cars, outboard motors, and marine engines – at least for the last 10-15 years - have been modified to accept 10% ethanol fuel. Many car manufacturers are offering models that can run on 85% ethanol fuel, as a way to reduce the country’s dependence on foreign oil and clean up the air even more. However, marine engines will not run on a mix of over 10% ethanol. The jury is still out on whether it takes more fossil fuel energy to make the ethanol and grow the corn than you get back when you burn the ethanol. 

One other point worth noting is that adding ethanol was supposed to reduce the total cost per gallon of gas. But in the last few years, the price of ethanol has risen from less than $1.50 to more than $2 per gallon. Transporting ethanol from the plant where it is produced to points thousands of miles away is not easy, adds to the cost and burns up diesel fuel in the tankers that deliver it!

Ethanol in the boat
Most boats have either metal, roto-molded plastic or fiberglass fuel tanks. Ethanol is a form of alcohol. Alcohol absorbs water & tends to collect moisture in the tank, either from condensation in the air or if introduced with the gasoline when it comes out of the ground at your local gas station. When this occurs, it has the potential to cause some internal corrosion in metal fuel tanks. There is one other problem, potentially a serious one, created in boats with fiberglass fuel tanks, particularly those in older boats. One thing that has surfaced is a rash of fiberglass fuel tank leaks and structural failures where ethanol has been introduced in the gasoline blend. Testing and chemical analysis by polyester resin experts have discovered that ethanol attacks and weakens the fiberglass resin, something along the same lines of the process that causes blistering of fiberglass boat bottoms. There have even been a few reports of epoxy resin tank failures. Many underground tanks at gas stations are also made of fiberglass. 

 As stated earlier,  marine engines were designed to tolerate gasoline containing 10% ethanol, but what about gasoline with ethanol that also contains some of the chemicals leached out of the fiberglass fuel tank resin? In their investigations, the experts found some peculiar engine failures involving a black carbonaceous build-up on intake valves that ultimately resulted in bent pushrods when the valves seized.  Analysis of the black substance on the valves and along the intake manifold passages showed that some of the component parts of the tank resin were present.  The tank and engine failures were a result of this chemical breakdown of the underground fiberglass tanks by the ethanol-gasoline mixture.

Closer to home, our service department is finding more and more cases of contaminated fuel. Much of this has been linked to ethanol fuel that has absorbed water from the air along with condensation from leaving fuel tanks less than full while in storage.  Just as you can see condensation form on your windows during warm days/cool nights, a fuel tank does the same thing. This has a tendency to clog fuel filters and water seperators as well as the small orifices in carburetors, fuel pumps and fuel injectors. Boaters should have thier marine mechanic take a fuel sample before the beginning of each boating season or if engine performance is sluggish or hard starting.

Boaters with older boats should avoid ethanol completely as it will deteriorate fuel lines, seals, squeeze bulbs and other rubber parts.

You should also avoid ethanol fuels during the hottest days of the summer. Ethanol(alcohol) has a lower boiling temperature than gasoline. As temperatures rise in a very hot engine compartment, ethanol will turn into a gaseous state causing "vapor lock". These air bubbles in your fuel lines may prevent fuel from getting to the engine. This will cause the engine to die or not restart after turning the engine off for awhile.

 Ethanol is probably here to stay, and fuel without ethanol is getting harder and harder to find every day. Our marina, as well as many others, are not selling ethanol blended fuel even though the cost may be as much as 15 cents per gallon more. Marine engines will run better without it and will avoid the problems mentioned in this artice.


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