Our new to us boat (2005 Hunter 36) is leaking. The backing plates on the seacocks is plywood. One of the valves is wet at the bottom. It leaks about a tablespoon every two hours or so. Is there any sealant I could apply to keep the water out? I don't want to pull the boat out just for this, the bottom was just painted. Do you think Flex Seal would do the job?