Boating Safety: E-10 and Antique and Classic Boats

The Former director of the ACBS Lake Hopatcong chapter, Edward J. Seugling, wrote a really informative article for the winter 2007 issue of ACBS Rudder on the 2005 law mandating methyl tertiary-butyl ether, as an additive in gasoline. Worth revisiting, particularly, if one is newer to the antique and classic boat hobby, Ed answered questions such as: 

• What happens to antique and classic boats that use E-10 fuel? 
• What about boats with large vented fuel tanks, which often are used for an hour or so on weekends, and which are often not run for long periods of time? 
• What effects does E-10 fuel have on older boats’ gas tanks, fuel lines, and the older engines? 
• Does seasonal storage, usually for at least six months, affect E-10 left in the fuel tank? 
• And lastly, will E-10 compromise antique and classic boat performance or cause safety problems with potential engine failure on the water? 
• How can we antique and classic boaters best adapt to E-10?

Read on…

The Federal Government passed a law in 2005 mandating elimination of MBTE, methyl tertiary-butyl ether, as an additive in gasoline. Ethanol, an alcohol created from fermented corn products, will replace MBTE in gasoline. The issue now for antique and classic boaters is, “How will this change to ethanol affect my boat’s performance and will E-10 create any special boat safety problems?” E-10, as it is known and often referred to as gasohol, is 90-percent gasoline and 10-percent ethanol. The purpose of this change in law was to improve air quality from combustion in gasoline fueled engines without including the negatives of MBTE. Both MBTE and ethanol are oxygenates and were designed to boost octane in gasoline while decreasing emissions upon combustion. However, small amounts of MBTE gas spilled from gas containers and leaked from other sources have led to contamination of ground water, whereas ethanol as an additive is soluble in water, and it does not create this problem. Since E-10’s introduction and refiner ramp-up of production, it is now the fuel that is commonly available for autos, boats, and small gasoline engines in most areas throughout the country and in Canada. 

One of the primary problems with the use of E-10 in boat engines concerns water entering the fuel system. 

Let’s look at the large vented fuel tank issue. I have a 1965 Century Coronado with a fifty-gallon tank. I try to keep the tank nearly full at all times. The worst case scenario is for water to enter the tank when the fuel level is half or less. Due to hot and humid summer days and subsequent cooling at night, condensation can form inside the half-full tank. With a nearly full tank there will be very little condensation, and little moisture will be drawn into the vented overflow tube on the stern of the boat. E-10 readily absorbs moisture; when water enters the tank, the ethanol absorbs the water and becomes diluted. If enough water enters the tank (about .5-percent in total volume), the ethanol becomes saturated causing the gasoline, water and ethanol to
separate. This is called phase separation. The gasoline remains on the top of the tank and the water and ethanol settle to the bottom, as they are heavier than the gasoline. Since ethanol
was an octane booster and is now on the bottom of your tank saturated with water, the regular gas that was rated at 87 octane has now been diluted to about 83 octane. A significant drop in octane can cause poor performance of your engine, including pinging and engine knock, potentially causing damage. 

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