[QUOTE=Wotname;1793771]The only fix that works is to remove the rotten plywood and replace it with new marine grade plywood."
Maybe, maybe not. Depends on the extent of the damage. If minor, perhaps you can scarf in a replacement, or just gouge out the damage and refinish. It will not be easy, regardless.
Have you stopped the leaking? That is critical and the first step.
There are penetrating epoxies that might be helpful.
Is there some way you could re-trim around the ports
and use that as an "architectural" feature?
Should be lots of ways to address. Use some imagination.