[neto]

On my 92 4300 Open, the fresh water tank is leaking into the bilge.  Is there any way to repair the tank without removing it from the boat.  Removing it will requiring cutting out a section of the floor, and I would like to avoid that if possible

does it keep any water? or is the leak at the bottom? If so, then most likely is at a tank's corner. I have known people that have perform what I am about to explain with good success. Drain the entire tank, dry it somehow, maybe open a hole that you can cover it later? then add a quart of clear flex seal liquid clear.. Use a stick and brush to spread it around covering the corners... Let it cure for a week then fill it up! Water would have a chemical smell for the first use, after that you should be good.

Another option is to use a liner.