In my boating area, all the gas prices are within about a dime of each other. About $4.59 right now. Some claim to be ethanol free and some do not. There is one car gas station, a Citgo, on a canal that also sells to boats at car prices. So the question is buy the non-ethanol marina gas or save almost a dollar a gallon with the Citgo? How much power loss is there with the ethanol fuel?

Depends on what you have. Ethanol blended fuel require a richer air fuel ratio, as the stoich level is different. It won't technically make less power but if you have custom engines, you may need to richen the motors a touch, will drop the power just a little. Ethanol is hard on the orings, fittings, injectors and mainly the fuel tanks in most boats.

Needless to say, if you can run without it, you're better off and less likely to have other issues.

Ethanol/E10 fuel will also vaporlock easier. You do not want to leave E10 in your fuel tanks for more than a few weeks since it attracts more moisture.

It won't technically make less power but if you have custom engines, you may need to richen the motors a touch, will drop the power just a little. Ethanol is hard on the orings, fittings, injectors and mainly the fuel tanks in most boats.