Very simple procedure (ask me how I know LOL)
1. Let the boat settle. Water is heavier than fuel, so it will sink to the bottom of the tank.
2. Remove your fuel/water separator filter. Place a container directly underneath where the filter was. This will be used to catch the fuel/water mixture that will be coming out of the tank.
3. Slowly pump your fuel bulb. This will drain fuel from the tank - starting with the water, because it's already at the bottom of the tank.
4. Empty the container that is collecting the fuel (water) underneath the filter into a clear glass container, and look to see if there is still water coming out of the tank. Dispose of this fuel/water mixture in the proper fashion.
Continue steps 1-4 until only fuel is coming out. Replace filter.