I was recently on a 120 foot fiber glass haul vessel helping out with some needed work. The captain on board wanted to dispose about 4 larger gallon jugs of denatured alcohol. He dumped the alcohol into a empty fuel tank that normally would hold about 1500 gallons of fuel, saying that it was good for the water accumaltion in the tank. I personaly did not like the idea not knowing if there could be consequences with the fiber glass tanks, MTU fuel systems, incapatable hoses, etc. But I was not planning on going out to sea in the vessel so I did not speak up. Does any one know anything about this and have some opinions?