J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Anyone done cabintop porthole replacement?

The side ports on my J30's cabin top appear to be UV-rotten Plexiglass. I am going to replace these with Lexan.

Anyone done this before? Any tips as to machining Lexan, installing, preferred adhesive/caulk material, etc.?

I am considering producing a drawing and having an internet/machine shop machine me up a set of 4.

regards,

Jack Curtis "Phat Cat"

I've just finished replacing three out of four this season; one more to go. I replaced them with plexi, but I figure in a few years I'm going to splurge on real opening portlights anyway, so the cost for lexan isn't worth it.

I removed the old one first to use as a pattern. It's just held in with caulk, which could be removed with unfortunate ease and the window pushed out. Getting the last of it out of the cabin top was a pain and getting the surface clean was a pain; I found copious amounts of acetone worked fairly well.

I then masked off the inside and outside of the cabin top, as well as the inside and outside of the window itself, with painters tape. I put a bead of cauk (The yard recommended SikaFlex which I used) around the inside frame, pressed the window in firmly, and then ran a bead of caulk around both the inside and outside frames. The cabin top around the two forward windows is slightly curved; I personally didn't find a problem getting the window to stay put and didn't need to resort to bracing it against a stanchion to bend the window.

Someone on this board recommended using a finger dipped in soapy water to smooth the caulk while it was wet; I did that, and it worked nicely. Then came the waiting game of peeling the tape off to leave a fine line. Too soon or too late makes a mess.

It doesn't look as professional as I'd like, and the SikaFlex seems to attract dirt, but I can see out the windows clearly and my water leak problems are gone, so I'm happy.

On the subject of machining....

With all the caulk that holds the window in place, I find it's difficult to get an idea of the actual window shape. I recommend removing one to use as a pattern rather than guessing with the window intact.

As far as I can tell, all four are identical in shape. Two are mirrored from each other. (Not sure if that is important; I don't know if Lexan has an indoor and an outdoor side to it.)

I personally used a jig saw to cut the portlights to size, fitted them, and used a sander to remove excess material where they would stick in the cabin top.

Good luck!

I replaced my windows about 4 years ago... with plex... and am getting ready to do it again... ALL of mine were a different shape.... had them cut approximate from a template then had to sand them to fit. I kept the original windows so this time I'll be cutting from them. Plex does not last in the tropics... it crazed within a year.

Go right for the opening ports. Lewmars fit nicely into the openings with minimal cutting.

The ventilation difference is amazing, you can add screens when cruising, and real glass never crazes.

I did mine about three years ago with polycarbonate. I scrounged around in the remnant bins at my local plastics supplier and found some with UV resistant coating that I got by the pound for about 50% of what branded Lexan cost. On his recommendation I lightly sanded the coating under where the caulk went (also SikaFlex...don't use 4200/5200..polysufide adhesives will eat the polycarbonate). I hadn't heard the "soapy finger" trick so mine look a bit ragged, but they haven't leaked in three years in the damp Northwest.

I see someone installed opening Lewmars? Do you happen to recall which port they were?
Thanks!
Doug.

Re. side ports. After going through 2 sets of Plexi I replaced them with automobile safty glass
bedded with black sekaflex. Used the old ports as a pettern and had a local glass shop cut the new ones. They were all slightly different in shape . 2 seasons now with no leaks, no scratches and clear as a bell.