The easiest way to drain the tank, (actually get the water out of the tank) is to get a primer bulb , put about 6 to 12 inches of rubber hose on the suction side of the bulb. On this piece of hose attach a piece of solid COPPER pipe. This is your "probe" to get into all the corners of the tank so you will need to be sure that it is long enough to get in the corners. Attach a piece of rubber hose to the outlet side of the bulb that is two to three feet long (this goes in your catch bucket). Pop up your access plate in the cockpit and remove the fuel gauge sending unit. Now you are ready to siphon the water out of the tank. Water is heavier than gasoline and the water will be in the lowest part of the tank . Use the copper pipe to move around the tank and siphon, a big boating buddy on one corner of the boat,if it's in the water will force the water to that side and corner. If it's on a trailer jack up the tongue as high as it will go. This will force all the water to the back of the tank. There is probably not as much in there as you think.
I had to do this about three years ago and got about two gallons out of my rear tank. Changed out all fuel filters and zero problems since.
Also make sure to put a new gasket on the sending unit. Also the gasket appears symmetrical but it's not.Rotate it until the 5 holes line up perfectly and then you're in business! Hope this helps!!!
Also the gas in the tank should be fine as gas and water will not stay mixed for very long . it will separate very fast after settleing down. for an idea on how fast this happens mix the two in a clear glass jar and shake them up.
