By Tom Nunes
Public Affairs Officer
U.S. Coast Guard Auxiliary
Division 10 - 11SR
BoatU.S. Technical Services, through surveyors and
boat owners has received a handful of complaints ranging
from destroyed engines to leaking fuel tanks. Oddly,
none of the owners reported clogging fuel filters.
The reports were mostly from Long Island Sound in New
York that had just switched to gasoline containing MTBE
to gasoline with ethanol.
It wasn’t long before ethanol became suspect. With
thousands of boats built with fiberglass tanks since the
1960s, the potential damage, as well as the risk of
explosions, was worrisome.
Adding to the concern is that ethanol is fast
replacing MRBE around the country.
BoatU.S. contracted with Rick Strand of Impact Matrix
Systems to test samples of two sections of deteriorated
fuel tanks that had been cut from 1967 and 1970 model
year Bertrams. Strand’s tests confirmed that the 1967
sample had an absorbed fuel content of 4.19 percent by
weight, and the 1970 tank had absorbed 4.22 percent.
Strand considers these amounts high for
polyester-based composites and about the most that this
type laminate could absorb. In comparison, he
says, the highest moisture content seen on badly
blistered samples of laminate is only about 4 percent.
Another independent test shed even more light on the
creation of damaging "black goo." Fred Hochgraf, senior
scientist at the New Hampshire Materials Laboratory,
analyzed damaged intake valves to determine the
composition and cause of the goo.
"After taking the extract down to dryness, we
obtained the infrared absorption spectrum. We found that
the material is di-iso octyl phthalate."
Gas Chromatography Mass Spectometry (GCMS) showed
that gasoline having 10 percent ethanol picked up four
very heavy molecules from fiberglass and two from the
filler. Hochgraf noted that a control sample with
straight gasoline did not pick up these molecules.
After evaporating a gasoline sample with 10 percent
ethanol, a heavy brown sludge remained. Infrared
spectroscopy showed molecular similarities between the
sludge and the material taken from under intake valves.
A dozen more reports have come in to BoatU.S.
Questions remained: What about California and the
Great Lakes? A call to the California Energy
Commission revealed one possible reason – California’s
gas has only 5.6 percent ethanol.
After a BoatU.S. press release was picked up by
California publications, frustrated boaters in
California and the Great Lakes began to call in
reporting similar symptoms. Because of the
difference in laminate quality, some tanks may take
longer to be affected while others suffer deterioration
Meanwhile, anyone with a fiberglass tank should keep
a wary eye out for black goo (look under the
carburetor.) An engine with goo should not be run
until it is cleaned. Thus far, the only cure is to
replace the fiberglass tanks wit aluminum or
polyethylene tanks. Or, as at least one boat owner
did, take the money he would have spent on a replacement
gas tank and use it as a down payment on a diesel.
Arizona already uses ethanol to boost the oxygen
content in wintertime gasoline. Winter fuels are 10
percent ethanol by volume. And ethanol demand has
increased in summer as well, since the state banned the
use of MTBE. The Phoenix metropolitan area,
including Maricopa County and parts of Pinal and Yavapai
Counties, are required to use special gasoline blends
during the winter and summer to meet federal air quality
standards. Tucson also uses a special blend during the
winter months. The rest of Arizona, outside the
metropolitan Tucson and Phoenix areas, uses conventional
gasoline year round.
All gasoline that is delivered to retail stations in
Maricopa County must be blended with ethanol (10 percent
by volume) to help reduce carbon monoxide emissions for
improved air quality. The blending of ethanol into
gasoline occurs at the terminal rather than at the
refinery because ethanol cannot be delivered though
pipelines. Ethanol is not delivered through pipelines
because it attracts and absorbs water that may be
present as condensation in the pipeline and thereby
contaminate the gasoline. Ethanol is also a corrosive
and continued transport of ethanol within pipelines
could compromise a pipeline’s physical integrity.
-Nunes developed this story from an article in the
Coast Guard Auxiliary Beacon, which is published by
the Coast Guard Auxiliary Association.