Go to an auto parts store and buy an after-market 12 V inline fuel pump - cheap ones are fine. Buy long hoses to fit on each end. Assuming boat is on a trailer, jack up bow of boat and jack up one side of rear axel to give the boat a tilt. Open hatch to tank. Remove the plate that holds the fuel pick-up tube. Snake the pick-up end of the fuel pump to the lowest corner of the tilted tank. Put the discharge end of the fuel pump into a suitable container. Start the pump and watch. Be prepared to use more than one discharge container.
The added benefit of this method is that it will get most of the crude out of the tank, too.
When you wire up the after-market fuel pump to the battery connectors (e.g. alligator clips), make sure that the connections are tight and completely covered. I usually use liquid electrical tape to do this.
Some folks may recommend simply disconnecting the fuel pick-up hose between the tank and the engine, and pumping out that way. My experience is that this procedure does not get all of the bad fuel out and can potentially clog up the end of the fuel pick-up tube.
