Boaters are now faced with a new problem - ethanol fuel. For years, gasoline
contained MTBE, an additive which controls the fuel's octane properties. The
additive is being phased out, and now much of the nation's fuel supply is a
blend of 10% ethanol and 90% gasoline, commonly referred to as E-10 fuel.
Ethanol presents several problems to boaters. The immediate impact of the
formulation is a loss of horsepower and fuel economy. Early indications show
drops of 3-5 % in of both categories. The loss of range sounds small, but adds
up on boats that are often already stretched to the limit in terms of fuel
needs. Additionally, ethanol is a very effective solvent, and has a tendency to
dissolve old coatings of varnish and dirt in existing fuel systems. This can
lead to plugged fuel filters, and other mechanical problems.
The added amounts of particles associated with ethanol
fuel may warrant upgrading filter systems. Many engineers
are now recommending that boats using ethanol fuel need to
use 10 micron filters. Pre-E-10 systems will likely be using
28 micron filters. Manufacturers such as Yamaha have been
quick to respond to ethanol fuel use by introducing
replacement 10 micron filters.
The corrosive
nature of ethanol can affect fuel lines and other components, causing them to
crack and fail. Many older boats will require replacement of all fuel hoses and
possibly other system components. Especially affected are boats equipped with
fiberglass tanks. Many older vessels must have the fiberglass tanks replaced
prior to using E-10 fuels, or face certain engine failures.
Water in E-10 fuel is another problem that boaters must deal with. The
introduction of water on E-10 fuel can be disasterous. E-10 can hold up to four
teaspoons of water in suspension per gallon. Once this saturation point is
exceeded, the solution separates and the gas floats on top while the ethanol and
water mix on the bottom. This event is called "phase separation". Ethanol fuel
can absorb enough water to reach it's phase separation point in just over 3
months at 70% humidity.
While the phase separation
slurry in itself can cause problems by clogging fuel systems, the more immediate
problem is that the remaining gasoline has now lost it's original octane value
which can cause poor running and in some cases engine damage. When phase
separation occurs, the fuel should be drained and replaced.
Fuel storage and winterization has to be handled differently when using E-10
fuels. Manufacturers are warning that fuels need to be stabilized if un-used for
as little as 2 weeks. Not all stabilizers are known to be E-10 compatible.
Non-alcohol based fuel stabilizer additives are a must for ethanol fuel.
See more on E-10 fuels from the
Volvo Marine Website.
A BOATUS article on
Fiberglass Tanks and Ethanol Fuel.
An
article on ethanol fuel from hawaii.gov
Ethanol News -
the latest information on ethanol as a substitute for the
high price of gasoline.
More boat maintenance
articles.