Found this one the EPA website:
Can you use reformulated gasoline in marine engines?
Marine engine manufacturers have indicated that the use of reformulated gasoline in their engines is acceptable, although some offer special instructions if you use reformulated gasoline. You should always check your owner's manual for any specific instructions.
As a boat owner or operator, there are a number of simple things you can do if you are concerned about using reformulated gasoline in your marine engine:
Be sure that your engine is properly tuned. The best thing you can do to make sure that your boat engine will operate properly on reformulated gasoline is to have your engine set to your manufacturer's tune-up specifications. While reformulated gasoline is very similar to conventional gasoline, there are differences. However, the differences are within the normal operating range of the engine and will not be noticeable unless your engine is out of tune. An engine using reformulated gasoline will operate at its best when properly adjusted to the manufacturer's tune-up specifications.
Minimize Water Contamination. Water contamination occurs when water is introduced into the fuel tank, and can be caused by improper storage conditions at the distribution center or retail station or by accidental introduction of water during refueling.
Reformulated gasoline contains chemical oxygen additives, commonly called oxygenates. These oxygenates are either alcohols or ethers. Currently, the most common oxygenates used are ethanol, which is an alcohol, and Methyl Tertiary Butyl Ether (MTBE), which is an ether. By nature, alcohol tends to have a greater affinity for water than ether-based oxygenates. If a fuel containing ethanol is used under conditions where water contamination is likely to be a factor, precautions should be taken to avoid such contamination. Of course, water contamination of any fuel blend should be avoided. Many oil companies are providing, or working to provide, clear labels for gasoline pumps to let you know which oxygenate is in the reformulated gasoline you're buying. If thepump isn't labeled, ask the service station attendant for information about the additive used in their gasoline. However, if you haven't had water contamination problems with conventional gasoline in the past, you shouldn't have a problem using either type of reformulated gasoline. To avoid possible contamination problems, the following fuel precautions should always be considered in storing and operating your boat:
Use good gasoline storage management. For many years, marinas have managed their tanks to minimize the effects of water contamination and deterioration. You should do the same with the tank in your boat. When storing your boat or gasoline container, make sure that the tank or container is either completely full or completely empty.
Use a water-separating fuel filter. Where you want maximum protection, a water-separating fuel filter will provide the greatest level of protection from possible problems with water contamination. So when you replace your fuel filter, choose the water-separating type.
Check hoses for deterioration at least once a year. Newer fuel systems are expected to be unaffected by oxygenated fuels. But some manufacturers are concerned that hoses in fuel systems produced before 1980 might be more prone to damage from alcohol-oxygenated fuels. Hoses that are susceptible to alcohol damage can become brittle or soft and, over time, deteriorate. EPA recommends that you follow the manufacturer's inspection requirements, with at least an annual inspection of hoses and other rubber components exposed to fuel. Components that appear deteriorated should be replaced.
Remember that by using reformulated gasoline you are improving the air you breathe, and protecting the air for future generations.