Re: Bad Battery?
From the looks of that jar, that is ALL water, not just mixed.
Pull the fuel pickup tube out of the tank, (have the bow of the boat higher than the aft so all the water runs to the back, then get an electric fuel pump from any auto parts store, hook up a hose and a small diameter copper tube to the pump and stick it down the hole in the tank and suck out ONLY the water. Put the gas back in the tank.
I do this to about a dozen boats every spring.
Just make sure you don't have a full tank when you remove the pickup tube.