There have been studies and tests being conducted recently by NMMA and American Boat and Yacht Council in hopes of finding a fuel that will not harm our boat engines. Currently there is concern that many boaters may unknowingly fuel up at the pumps using gasoline with 15% ethanol which will probably be mandated in the U.S.; this type of fuel has been proven to work well in 2001 and up model cars and trucks, but it is not compliant for boat engines. Fueling your boat up with gas containing anything more than 10% ethanol could be disastrous for your engine.
Preliminary tests and evaluations on isobutanol (a promising biofuel alternative) show that the emissions produced are no more than pure gasoline approved by EPA. This is interesting considering tests also show that it produces 30% more energy than E15. These studies have support from much of the boating industry including Bombardier Recreational Products and Volvo.