i difinitly dont want to install one if i cant find any that doesnt leak.
Lewmars have a reputation for leaking. That's why I posted that thread. There may well be others that don't, but I personally don't know of any. The Lewmar discussed in that thread was a non-opening portlight, too. A friend with a C34 did one in his aft cabin, don't recall the make. New Found Metals has a very good reputation for portlights, try them. I still think you'd be better off with an opening portlight into the cockpit for both light AND ventilation. And, you could use a less expensive Beckson, like a 5x12, since they are ubiquitous and have parts availability. They still make the same ones as are on my 1986 boat, and I have eight of them.
To see the water when you wake up, you could consider a periscope!
Further discussion on the C36 board says:
Mine leaked, too. You're correct that it's in 2 pieces, an upper and a lower aluminum frame, with a rubber 'gasket' between the 2 pieces. The gasket is what was leaking. I contacted Lewmar and the ports can't be fixed. So, I bought a new one. I was lucky that they still had them in stock as they've changed to a more rounded profile in the current line.
However, I decided not to replace the port, and to fix the seal instead, keeping the port as a spare. I took some clear silicone and forced it into the gap between the upper and lower frame pieces and covered it with electrical tape, so it would harden flush, and to protect the remaining rubber gasket from the UV light that caused it to fail in the first place. That black electrical tape is still on there, and has been there at least 5 years...!!! I trimmed it flush with the edges of the frame and it looks like it's supposed to be there.
So, check that rubber seal between the upper and lower frames. Mine was obviously leaky, you could see light from inside the aft cabin once the trim ring was removed. Lewmar confirmed that they degrade; I'm surprised none of my opening ports leak. My 'fix' has held and no more leak in the aft cabin.
and
These Lewmar’s commonly leak at the rubber gasket between the two halves of the frame. My wife and I bought a 1999 C-36 last year and all the top side ports leaked. The rubber gasket material was gray and soft enough that I thought it was actually caulking. On the 1988 Catalina 30 we sold, the same Lewmars had black rubber gaskets that were good as new and never leaked. The black rubber gaskets must be much more impervious to UV, because they were still hard, after 20 years.
I took a metal pick and removed much of the soft gray rubber gaskets at the two joints and caulked the gap. No more leaks.
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Your boat, your choice.