July 13, 2006
Ethanol – The Industry’s Big Secret
The new buzz word these days seems to be "ethanol". Everywhere you go these days you see or hear it; on the news, political speaches, stickers on the gas pumps, and now slowly but surely my boating magazines. Until recently we haven’t heard much about it with boats – but it’s probably the single biggest issue about to plague the marine industry.
Today, ethanol is used as a fuel additive that boosts octane and serves as an oxygenator which supposedly helps clean up an engine’s exhaust by making it easier for the catalytic converter on cars to do their thing. Ethanol used to be more localized in the mid-west, but today it’s being seen throughout the country and finding its way to our fuel docks. What’s more, not only is ethanol found in more of our fuel, the amounts continue to rise. (Most engines are designed to tolerate up to 10% ethanol)
The problem: Fuel containing greater than 10% ethanol content poses a safety risk by damaging fuel tanks and engine components. The National Marine Manufacturers Association (NMMA) recently published a strong and alarming position paper opposing the use of marine fuels with an ethanol content of over 10%.
The increase use of ethanol will wreak havoc on aluminum and fiberglass fuel tanks. Increased levels of Ethanol can cause significant corrosion of aluminum fuel tanks. The problems with ethanol all stem from its hydroscopic property, which means it absorbs water. Bottom line: More Ethanol in Fuel = More Water in Fuel. Water corrodes the aluminum tanks. As corrosion occurs, particles will begin to clog fuel filters, fuel systems and damage engine components. Over time, corrosion can perforate the aluminum which will cause fuel leaks.
In addition to corrosion caused by water, there’s also increased risk of galvanic corrosion. Gasoline fuel by itself is not conductive, but with ethanol it will conduct electricity. The same galvanic process that occurs to outdrives and other components in the water will occur within the aluminum tank with increased levels of ethanol. The big difference though is that it’s impossible to install sacrificial anodes (zincs) inside the tank like we do on the outside of the boat.
Plastic and fiberglass tanks aren’t really any better off either. For molded plastic tanks, ethanol increases permeation of the tank walls. For fiberglass tanks, ethanol can cause leaks, but more importantly, there are reports that ethanol causes heavy black deposits on intake valves of marine engines which causes bent push rods, pistons, and valves. Testing is currently underway to fully determine the effects of ethanol on fiberglass tanks.
Now more than ever, it’s extremely important to inspect your tanks for leaks and the bilge for fumes. It is strongly recommended that at the end of the boating season you should have your fuel tanks drained and flushed to prevent tank corrosion.
In a future posting I’ll examine what we can do to prevent and minimize the damaging effects of ethanol. From what the data shows, as long as ethanol content remains at or below 10% we should be OK – the concern is what happens if ethanol content continues to rise?
Posted by ribcraftusa at July 13, 2006 10:57 AM
Comments
Everything I've read says that boats with FRP fuel tanks are (is) going to have the biggest problem. The good news is not too many boats are built with fiberglass tanks. Older outboards are having problems.
This seems to be a big problem that the industry is trying to keep hush. Why? Are builders afraid of losing buisness? It will be a boon to the service guys.
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