Ethanol and Boats May Not Mix Well
We reported on this some time ago and now I read that NSW Maritime in Australia is warning boaters to be aware of ethanol in the gasoline they use. They have raised a couple of significant concerns. Ethanol can affect some fuel lines, seals and gaskets and can also affect fiberglass fuel tanks because of its solvent properties.
Here’s what it’s all about:
Methyl tertiary butyl ether (MTBE) is one of the nasty chemicals in gasoline. Alcohol - either ethanol or methanol - does the same job. It works just as well. It has an added eco-friendly benefit in that it reduces emissions of benzene and does not contaminate groundwater. Unfortunately, when fuel with ethanol sits in a tank for any length of time, it can cause serious problems including leaks, clogged filters, and poor engine operation.
Depending on the amount and type of alcohol used, the gasoline mixture may be more volatile and harder for the fuel pump to, well, pump, especially in warm weather. Ethanol fuels are also more subject to vapour lock when the engine is warm. Older engines may need to be retuned.
The other big problem with alcohol is that it attracts moisture. When alcohol absorbs moisture it becomes heavier than gasoline and sinks to the bottom of the tank. In a 100-gallon tank you can have nearly ¾ gallons of this mixture, plus you have gasoline with no oxygenate. It doesn’t burn well, so your engine may run rough, stall, or not even start. What’s worse, the mixture of alcohol and water can form strong acids that attack the fuel tank and other components in the fuel system.
Alcohol can cause rubber and plastic parts to swell and weaken so they may not seal as well. What’s more, alcohol molecules are smaller than gas molecules so older rubber fuel lines may be permeable to alcohol.
You can minimize the bad stuff and keep the good. Don’t let ethanol fuel sit for a long time. If you’re not going to get out and run your boat, don’t put a lot of fuel on board. A non-alcohol fuel stabilizer (Mercury/Quicksilver Gasoline Stabilizer for Marine Engines) is a good idea, too, especially if the boat sits. At the end of the season, make sure the tank is dry. Rubber fuel lines installed before the mid eighties should be replaced. While you’re at it, get rid of the old, weather-faded plastic portable gas tanks. Install a good water-separating fuel filter; keep a stock of spare fuel filters handy and learn how to replace them yourself if you don’t already know.