Ethanol Replacement for MTBE May Affect Boats
There is a federal mandate for producers to use a certain amount of ethanol and no apparent economical way to keep it out of marinas.. Due to the corrosive nature and affinity for water, ethanol is added at the tank truck just before delivery and the same truck that goes to the corner gas station also goes to the marina.
There are several issues –
First is a safety issue
for those boats equipped with fiberglass gas tanks, generally those made
before the mid-80’s. Ethanol tends to dissolve certain resins, which then
find their way through the engine intake and coat intake valves, which makes
them stick causing bent pushrods or worse. More important is the possibility
of a gas tank degrading to the point of leaking. As anyone knows, gas is the
bilge is an explosion waiting to happen. In addition to boats such as
Hatterases, Betrams, and Chris Crafts made before the mid-80’s, some smaller
boats, notably Boston Whaler Montauks, have small above-deck fiberglass gas
tanks. Some of these tanks have been reported leaking as well. Any boat with
a fiberglass gas tank that was not specifically designed for ethanol should
be suspect. There are some resins that are immune to ethanol (some vinyl
esters, for example) and are used in underground gasoline storage tanks, but
most resins, including common epoxies are not able to withstand contact with
ethanol. Though it’s no comfort to those with fiberglass gas tanks,
fortunately, only a very small percentage of boats have them.
Second is the addition of alcohol to gasoline adversely affects the volatility of the fuel, which could cause vapor lock.
Third is ethanol can also affect many plastics and rubber. Alcohol present in automobile gasoline is not compatible with the rubber seals and materials used in boats, however, most fuel hoses made after 1984 and marked with SAE J1527 are designed to withstand ethanol. Some older fuel filter bowls made of plastic may be affected and some seals, o-rings, or plastic parts could be damaged.
Fourth is phase
separation, which happens when the fuel is cooled as a
result of the vessel operating in winter weather. When the alcohol separates
from the gasoline, it may carry water that has been held in solution and
that cannot be handled by the sediment bowl." This may affect performance
and drivability. Ethanol absorbs water readily and as little as .5% water
will cause a phase separation. A water/ethanol mixture, being heavier than
gas, will sink to the bottom of the gas tank, leaving a lower octane gas on
top. This low octane gas can cause performance issues with 4-stroke engines,
but can cause damage with 2-strokes due to a lean condition. In addition,
2-stroke engines can be damaged if a quantity of water/ethanol is ingested
since the proper lubricating oil won’t be present. Keeping water out of the
tank is obviously important.
Fifth and another problem with
the introduction of ethanol comes from mixing gas with MTBE and gas with
ethanol, especially in the presence of water. This chemical soup is believed
by some manufacturers to create a gel-like substance that clogs passages in
carburetors, most notably in outboards. Stalled engines and shop bills are
the result. Fuel injected engines seem to suffer much less than carbureted
ones.
When ethanol is first introduced, you may experience more frequent fuel
filter replacement as ethanol’s superior solvent properties cleans old
varnish and other stuff from the tank. Gas with ethanol also typically
delivers slightly less fuel economy.
WHAT CAN YOU DO
For those with affected fiberglass fuel tanks, the only sure cure is
replacement, usually with aluminum. Ethanol itself does not appear to affect
aluminum, except when mixed with water, where it may contribute to internal
corrosion. Polypropylene gas tanks are unaffected by ethanol, according to
manufacturers. Those with fiberglass gas tanks are urged to install a vapor
detector in the engine space (a good idea anyway) until replacement can be
carried out. And checking for the black substance under the carburetor or in
the intake manifold will alert you to the fact that intake valves are also
being coated.
Keeping water out of your gas tank is important! Keep your tank filled if
you are in an area with large daily temperature swings to prevent
condensation, but remember that gas with ethanol has a shorter shelf life -
use it up. Boats that are going to sit for long periods should store the
tanks empty if possible. Note that gas drying additives are typically simply
ethanol and won’t help. The installation of a water separator in the fuel
line can help with small amounts of water. Outboard manufacturers also
recommend adding an injector cleaner to the fuel.
Keep some extra fuel filters on hand, especially during the first season.
Most marinas are not required to post ethanol content on fuel pumps.
Hopefully, marinas will be extra careful to avoid water contamination of
storage tanks. If the lessons of Long Island Sound, where ethanol was
introduced a couple of years ago hold true, problems will begin during the
changeover and should lessen as the season progresses.
portions of the above found on BOAT U.S. website below
http://www.boatus.com/seaworthy/default.asp
A thank you goes out to P/C Ralph Dolinger for finding and forwarding this article for addition to the web site.