Newly reformulated gasoline with ethanol could rupture old fiberglass tanks
Written by BoatU.S. Alert   
Friday, 14 October 2005 12:25

Explosion Hazard and Significant Engine Damage Evidenced on Large, Older Vessels? Older fiberglass fuel tanks may fail as a result of recent gasoline reformulations that are using increased concentrations of the fuel additive ethanol.


BoatU.S. believes that as a result of industry-wide changes in fiberglass resin formulations in the mid 1980's, the problem appears to be limited to tanks manufactured prior to this date. Diesel fuel systems are not affected. The fiberglass fuel tanks in question were standard equipment on some Hatteras, Bertram and possibly other boats. While the investigation is still in the preliminary stage, BoatU.S. believes that reformulations made to gasoline in the Long Island Sound area that replaced MTBE (Methyl Tertiary-Butyl Ether) in late 2004 with a 10% concentration of ethanol is causing the additive to "attack" the resin in the old fiberglass tanks. The results are weakened tank walls and bottoms with the potential to leak.


Anytime gasoline leaks into the bilge, there is a significant risk of an explosion.

BoatU.S. has confirmed reports of tank wall failure in which gasoline was found leaking into the bilge. It also has reports of a tar-like substance - possibly created from the chemical reaction between the older fiberglass resin and ethanol - causing hard black deposits that damage intake valves and pushrods, ultimately destroying the engine.

"At a minimum the problem can devalue a boat significantly since replacing damaged fuel tanks and engines can be a significant expense. However, the potential for leaking and explosion is a far greater factor," said Chuck Fort, associate editor of Seaworthy, the damage avoidance newsletter from BoatU.S.

BoatU.S. is asking boaters for any firsthand reports or other information they may have on the issue and is doing additional testing to evaluate the extent of the problem. "We'd like to know if other gasoline reformulations with lesser concentrations of ethanol react with the resin, perhaps at a slower pace," said Fort.

The increasing use of ethanol has largely been the result of federal and state efforts to replace MTBE, a potential carcinogen, with a safer alternative. MTBE and ethanol oxygenate fuel to help reduce harmful emissions when running cold engines just after startup. BoatU.S. has no reports from other states using lesser concentrations of ethanol. "Many well-regarded boat manufacturers have used fiberglass tanks reliably for years," said Fort. "But unforeseen by these builders, the new reformulation in New York and Connecticut includes a high percentage of ethanol. And unfortunately, gasoline with ethanol is the only fuel available to boaters in these areas," he added. Some stations in New Jersey may also be using ethanol-enhanced fuel.

If you have any information on the issue, please contact Fort at 703-461-2878, ext. 3033 or email This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Early symptoms may include engine backfiring and hard (sluggish) starting, in which the motor turns over slowly as though the battery were weak.

Affected engines also may not reach their rated RPM. Fort said,

"Ironically, the substance seems to pass through fuel filters leaving no tell-tale marks - some have appeared clean on our reports. The only way to know for certain is to pull the carburetor and inspect the underside for a black, gummy film which can indicate a serious problem."

Until it fully understands the extent of the issue, BoatU.S. is recommending that any early 1980's or older vessel with fiberglass gas tanks be stored empty over the winter.

You need to login or register to post comments.