The People of America's Oil and Natural Gas Indusry

E15 and Boats: Don’t Get Left High – And Not So Dry

Mark Green

Mark Green
Posted July 17, 2015

Lots of people are concerned that increasing the presence of E15 in the nation’s fuel supply could have adverse impacts on devices powered by gasoline.

Studies show E15 can damage engines and fuel systems in cars and trucks that weren’t designed to use it. (Click here for a matrix that shows most vehicles on the road today aren’t recommended for operating on E15 by manufacturers.) Motorcycles and outdoor power equipment could be negatively affected by using E15, too.

That’s a concern of marine engine manufacturers and boating enthusiasts as well. Below, one of three new API cartoons takes a humorous look at a very real issue specific to boaters, which is the risk of engine failure when out on the water:


A study by Mercury Marine Product Development and Engineering:

Marine engines require unique considerations when altering the fuel supplied to operate the engine. Considering these engines are frequently used in remote locations (offshore fishing for example), it is critical to ensure that the fuel does not cause or contribute to an engine malfunction.

The National Marine Manufacturers Association is concerned about potentially dire effects on boat engines from E15 by accidental misfueling:

NMMA strongly opposed – and continues to oppose – the granting of a “partial” or “conditional” waiver for E15 or any other ethanol blend level over ten percent ethanol (“E10”) because it will substantially increase public confusion and lead to persistent misfueling and consequent engine performance failures, emissions control failures, and consumer safety concerns.  

Thermodynamic Development Engineer David Hilbert:

E10 fuel has 3% oxygen while E15 fuel has 5%-6% oxygen. On a typical marine engine, this additional oxygen makes the fuel burn hotter, and the higher temperatures can reduce the strength of the metallic components. In addition, ethanol can cause compatibility issues with the other materials in the fuel systems because of the chemical interaction.

NMMA President Thomas J. Dammrich:

… we have determined that e15 blends of ethanol would cause considerable damage to the 7.5 million outboard engines in use in this country today. This damage is unnecessary and can be avoided by freezing the ethanol content of gasoline at 10% by volume. NMMA has never been anti-ethanol. We are simply opposed to fuel blends that will ruin our engines and place lives at risk.

Reliability and safety clearly are paramount concerns associated with E15 for American consumers – boaters, motorcyclists and home owners.  Driving the E15 is the flawed Renewable Fuel Standard (RFS), with mandates for ever-increasing ethanol use in America’s fuel supply that is more focused on political interests than consumer interests. 


Mark Green joined API after a career in newspaper journalism, including 16 years as national editorial writer for The Oklahoman in the paper’s Washington bureau. Mark also was a reporter, copy editor and sports editor. He earned his journalism degree from the University of Oklahoma and master’s in journalism and public affairs from American University. He and his wife Pamela live in Occoquan, Va., where they enjoy their four grandchildren.