Quote Originally Posted by stp012 View Post
Remote oil filters are lagged to the side of the stringer. I was trying to break the filter loose and the whole bracket ripped right out with all 3 lag screws. I stuck a screwdriver in the hole and was able to push it all the way to the other side of the stringer. I checked the engine lags and a couple of them wouldn't tighten. Drilled a few exploratory holes to confirm my biggest fear.

Thankfully the engine room stringers are separate from the rest of the boat so the damage ended there. The engine room stringers are made up of flat layers of 1/2" thick plywood, while the rest of the stringers are solid beams. My guess is the moisture crept right through the hull over the years. They built these boats with polyester resin which is not waterproof. My theory is the holes (engine mounts etc) in the stringers combined with the engine vibration allowed a 'path' for moisture to travel through them. Being plywood probably didn't help either.
Did you us flat strips again or did you put marine ply vertically in stringers.