I have a 1990 18 Wellcraft - the batteries are located in compartments in the stern of the boat -port and starboard. In the starboard compartment it appears that the inital intent was to fill the space between the stringer and hull with foam forming a support for a piece of plywood that was then glassed in. The battery then rest on the plywood. The wood rotted and battery "fell" into a hole. Now that I have it taken apart, it appears that the foam does not reach the transom. There is a 6 inch space in which water has collected and has no place to go. When the wood gave way - the battery fell into that pocket. The other side is foamed all the way to the transom and does not have the same problem.<br /><br />My thinking is that I need to fill that space with foam, replace the wood with something that won't rot - and then glass it all in - all of which I have not done before. Any thoughts on how to get it done right?