Ethanol in Gasoline as a Marine Fuel

These past few years there has been a lot of scuttlebutt surrounding the use of Ethanol in gasoline sold for marine use. Ethanol (ethyl alcohol) is the same type of alcohol found in booze and is produced agriculturally from crops such as potatoes, sugar cane and corn. In North America it is common to find ethanol levels up to 15% in commercially available gasoline.

Ethanol has three characteristics which as boaters we need to be aware of:

  • Ethanol is more corrosive that gasoline. It can attack aluminum engine fuel system components and it can be very damaging to many types of rubber, neoprene and yes even fiberglass. Since boats, in many cases have a much longer service life than cars, a large number of boats in use today were manufactured before ethanol was even considered as a motor fuel component and as such, engines and fuel systems are susceptible to its corrosive effects. This includes carburetors, fuel injectors, fuel pumps, neoprene fuel lines and tank fill hoses, fiberglass fuel tanks and any other component that is used to convey fuel.
  • Ethanol is Hygroscopic. As we learned in a past post about fiberglass hull construction, hygroscopic means that it can absorb water. This can affect its corrosiveness and with water being a conductor of electricity can make static electricity build up at the filler neck even more of an issue.
  • Ethanol when added to gasoline severely shortens the fuel’s “shelf life”. In many areas due to the onset of winter weather boats are hauled out and dry stored for 6 months every year. In these scenarios a fuel’s shelf life becomes an important issue.

So what does this mean for us boaters? Let me start by saying that the automotive world has largely adapted to these changes and cars and trucks available today are “ethanol friendly” and are for the most part immune to the potentially damaging effects of ethanol gasoline. Also cars and trucks are generally not stored for months on end so a fuels shelf life is usually not an issue.

The next question is, as a boater how do I know if a fuel contains ethanol or not. It “should” be noted on the gas pump in plain view but be careful, it may not be and depending on the area that you’re in it may not even be required. There’s a great website that I highly recommend that you visit if you wish to re-search this further. It is

Now let’s suppose thatif  your boat resides in an area where it is impossible to obtain ethanol free fuel, let me offer a few tips.

  • Of course first the obvious. Try and use ethanol free fuels whenever possible. The best way to counteract the effects of ethanol is by the use of a quality fuel additive. There are many on the market and I suggest that some fairly extensive re-search is in order.
  • Since neoprene is used extensively on boats for fuel lines and fill hoses and the only types of neoprene that are ethanol resistant are USCG Type A1, A15 and A2. ABYC recommends that A1 and A15 are the only types to be used as fuel supply lines and A2 is the only type recommended as a tank fill hose I highly recommend that you replace any lines and hoses that are not of the above types.
  • If your boat is fitted with a plastic or Marelon deck fuel fill fitting I recommend that it be replaced with a metal one and that it be grounded (connected with a wire) to the remainder of the on board metallic fuel system components. This will allow you to equalize the fuel’s static electrical current build-up by touching the fill nozzle to the grounded fitting. Plastic fittings do not allow for this
  • Don’t forget about you outboard motoes and gensets.

That’s the basics for now but since this is a very hot topic I will no doubt be posting on this subject again as we move forward. Consider this: Since we have now figured out how to “grow” gasoline I would expect the levels of ethanol in fuel to increase rather than decrease.

Stay tuned!