When we took over the boat, all the ports were leaking with enthusiasm. This had caused serious damage to the interior cabintop panelling. Some of the leaks where around the window frame. Others were around the screws that fixed the other teak frame, which were screwed straight through the GRP cabin top. In addition, the drainage from the frames of the original opening ports were through a small pipe through the GRP and outer teak planking, and around these water had also found a way to enter the cabin.
In addition to leakage problems, removing the portlights also revealed a safety issue. It turned out that the only thing that had kept the portlights from being pressed into the cabin by a huge breaking wave all these years had beed luck (absence of huge wave) and the tiny wood screews holding the internal steal frames to the wall! Shuddering in my belt and braces, I therefore concluded that the windows not only needed re-bedding; we needed a better design.
We chose three different solutions. Most of the portlights were replaced by opening stainless ports from Newfound Metals. Expensive, but great quality. We had to add spacers on the inside, but otherwise it was just a matter of following the instructions. We re-used two of the original Cheoy Lee opening portlights, but to make the installation safe we had solid stainless frames machined. These were put on the outside, and through bolted to the integrated portligth frame on the inside. The drainage holes were plugged permanently. Last, the big windows by the nav station and in the aft cabin was replaced. The old plexiglass was replaced by Lexan (polycarbonat) which was bedded with Sikaflex in a broad groove that was routed into the external teak around the window. The glass was thus flush with the external cabin top wall, and cannot possibly be stove in. A new external teak frame was made to cover the overlap and protect the Sikaflex from UV radiation.
I should mention that while we were at it, we also replaced the profoundly dead internal plywood lining. It came of with persistent use of various tool and patience, revealing a rough GRP surface. It was replaced with a new birch plywood lining. This was epoxied on the back, glued to the rough GRP cabin top, and painted white.