I have a 1974 Coronado 41. Ever since I've had the boat, there has been this one poorly repaired crack through the hull that has bothered me. I assume it was just patched with some kind of surface expoxy/filler mixture because the damage was by a window and they didn't want to take out the window to repair the fiberglass.
I now have the windows out (they needed replacing anyway) and I can't let myself reassemble the windows without fixing this crack. The crack is about 4 inches long and goes all the way through the hull laminate and also went through the interior cabin liner. There are some stress rings above the crack which I have to dig into and see how deep they are - hopefully not all the way through the laminate. The deck is solid 1/2" vinylester layup so I won't have to replace core.
I have done some vinylester lay-up repairs in other places but usually in areas where there's a hole or such that the mat can be installed in an all-around beveled area. I usually follow the very basic procedure by Don Casey for fiberglass repair: Fiberglass Repair by Don Casey
But with this one I am wondering if there is anything different to do since the damaged area is right up to a window frame. I plan to cut out a somewhat circular area around the damage and bevel it towards the inside of the boat. I will have to cut out an even larger circle on the headliner on the inside to get access. I plan to stick a plexiglass sheet with mold release against the outside of the hull with some kind of flange to match the window curve and lay the mat into this shape a few layers at a time wetted out with vinyl ester resin. I don't know if I will gelcoat it since it is mostly in this blue area which I had painted in the past.
When the hull repair is complete I can re-build the liner and gelcoat on the inside.
Does this sound like a good approach, or does anyone have suggestions of a better way?
Crack in the upper right corner of the window:
Close up from the outside:
Sort of cross section:
Crack from the interior (I'll need to remove that bookshelf above I guess)