gasoline pump at a dock
gasoline pump at a dock

Alternative Fuels

Alternative fuel can be a good way to green your boating but it's important to know that not all alternative fuels are the same. Before switching to an alternative fuel, make sure you do your research on what will work best for you.

Ethanol or E85

Ethanol has been giving boaters headaches and is best to be avoided if possible. Learn more about Ethanol in boats by visiting our many articles on Ethanol.


Biodiesel can be a great alternative to conventional diesel fuel. Biodiesel is usually blended with petroleum diesel at different blends up to 20 percent biodiesel or B20. Biodiesel is domestically produced from vegetable oils. It burns cleaner with reduced air emissions, reduced soot, smoke and carbon monoxide emissions. Use of biodiesel also helps to reduce green house gases. Biodiesel has improved lubricity is also less toxic to marine life, though spilled biodiesel must be treated the same as spilled petroleum diesel or gasoline.

A few things to know when using biodiesel:
  • Biodiesel is a great solvent. It will clean out your tanks and lines and bring all of that gunk to the filter, so you will need to change your filter more often.
  • Biodiesel can also soften and dissolve the natural rubber hoses and seals. Some say to replace all lines, gaskets and seals with synthetics before switching to biodiesel.
  • Biodiesel, like petroleum diesel, can be problematic in cold climates.
  • Before using biodiesel you should check your engine warranty.
  • Biodiesel has a shorter storage life, so ensure that the vessel is used frequently.
  • Like petroleum diesel, biodiesel is prone to microbial contamination, so it is important to keep sound fuel management practices and keep water out of the system.
  • It is important to keep tanks near full to minimize condensation of moisture.


Propane is another alternative fuel used in boats. You can learn more about propane engines from our Foundation Findings.


Isobutabol is another bio-fuel that is showing some promise in the marine market. Isobutanol can be blended with gasoline but in early tests does not pose the same problems of ethanol.