What Every Boater Should Know About Ethanol

Boating and Ethanol: What you should know

The Boat Owners Association of the United States wants you to know the do’s and don’ts of keeping your engine running smoothly, saving you from costly repairs. Most boats use gasoline, at least the powerful ones, and the majority of gasoline products sold in the US contain ethanol, although there are ethanol free options they are not as commonly found.


Boaters should never use a gasoline which contains more than ten percent ethanol. Now more than ever boaters need to be aware of what is going into their gas tanks. While most gasoline brands are designed to burn E10 (10% ethanol), some retailers are selling gasoline with ethanol ratings of E15 (15% ethanol) to E85 (85% ethanol)! Using gasoline with more that 10% ethanol is against the law and will likely damage your engine and void the warranty – watch for labels on the pumps at your gas station before filling up. Or better yet, fuelling at the dock is a great way to ensure that you are using fuel with the correct rating, remember E10 or less.


Be wary of storing E10 gasoline on your boat for extended periods of time as it can result in phase separate. This process occurs when condensation combines with ethanol and creates a corrosive mixture at the bottom of the tank. Phase separation can not be reversed with a fuel stabilizer; you will need to drain the tank. Keeping a full tank of fuel over the winter months can keep you from experiencing phase separation in your boat tank.


Unless you are looking to cash in on an insurance policy, it is recommended that you never plug up a fuel system vent. Doing this is an explosion hazard that your dock and storage neighbours will not enjoy.

Safe boating is enjoyable boating!