Hey Stosh,
If your boat is around ten years old or more, you might have accumulated water in your fuel tank. If you can access the fuel sender and remove it you can take a suction oil changer and suck the bottom of your tank.
With your boat on a trailer, tilt it up on one side by towing one tire it over a large block and then jack the trailer tongue up as far as it will go.
The water in the tank will then settle to the lowest corner of the tank and you can suck all the water out leaving the fuel in the tank.
Remember, water is more dense than gasoline and will collect at the bottom of a tank, filter or carburator.
I did this to an old boat of mine after it started coughing it up into my filters and got almost a gallon of water out!
Good luck and go RACOR!