Tech Wiki

Fixed Portlight Repair

Repair or Replace Plexiglass Cabin Windows

by Ron Hill, Apache

Q: Can I replace or fix the Plexiglas, Black Tinted Cabin Windows?

I am preparing to replace the fixed cabin windows on my boat. I did a search in Tech Notes to find any info on the best/easiest way to remove the old windows. I need to remove them intact so I can use them as templates. I couldn't find any info. Any thoughts?

Chap Hodges, C34 "Kemosabe"

Chap, As I recall, your hull # is 344, which I think makes you a 1987 year production boat. This is important because I'm going to recommend that you get your side port replacements from Catalina - at least compare their price with that of a local supplier. I believe yours are going to be the new ones that they changed to in 1987. When you call Marvin at Parts, give him your hull #.

There aren't any articles in the past Mainsheets on replacing fixed windows that I'm aware of. I did put this on the C34 Net back in June 1998. Guess it must have slipped through the "FAQ crack"!

As far as removing them, I believe that is fairly easy. Remove the screws that are holding the panel/panels in place. Insert a putty knife about 1-1/2" wide (careful with the gelcoat) and pop out one corner. Then you are going to take the putty knife and just go along breaking the seam all the way around until the entire edge of the window comes out. The most difficult spots will be the areas between the galley and the aft cabin (starboard) and the head and above the Nav table (port). There is about a 4" area of solid caulking there. You may end up breaking the window.

Before installing the new windows, make sure that the indented surface is absolutely clean. Lacquer thinner works well. Pre-drill the new windows by using the old window as a template. Apply a liberal amount of caulking, and when you think you put too much on, that's about the right amount. (Catalina uses black Dow 795 Silicone for sealant, I prefer polysulfide). Make sure there are NO voids in the caulking. Hopefully, your new windows will have a protective paper like covering still attached. On the inside of the window, remove the covering, leaving the covering on the outside of the window. Before pressing the new window on to the caulk, use small pieces (approx. 1/2" long x 1/4" high) of foam tape every 4" on the inside of the window toward the sealant. This tape will maintain 1/8" thickness of sealant when tightened down. Otherwise all the sealant will squirt out especially in the center where there is a contour. Press the window firmly on to the caulking and replace the screws to hold it in place. DON'T touch the caulking on the inside or outside. Let it dry. It may take a few days. After it has hardened, take a single edge razor blade or X-acto knife and trim the caulking from the window both inside and outside. Easy, so you don't scratch the window. Be careful on clean up if you use lacquer thinner or acetone as it is not too friendly to acrylic and will leave marks (try mineral spirits first). Last step; take the protective covering off the outside. Hope this helps.


Chap, Ron copied me on his response. Here's a note I sent recently to Al: We had a leak in the big fixed window on the port side. I ended up taking the whole thing off and rebedding it in silicone yesterday afternoon after we anchored. It leaked so bad it had drenched my portable radio cassette deck that was on the shelf above the nav station. The whole window was loose in the frame. Also there was one screw missing from the forward lower side of the port aft fixed window over the head. They're bedded on some thin rubbery stuff with VERY short screws.

I ended up checking all the screws on all the fixed ports.

In retrospect, if I had some on board, I would have used clear sealant, although I was careful enough so that the white stuff didn't ooze out all over the place. Plus at least I can see that it's consistent all the way around. Rained like blazes here last week, checked today, no leaks. Next fun and games are the Beckson ports. BTW, why are you changing them out? I probably messed up the tiny rubber seal inside the frame by doing it this way (without Ron's great input). This seems to be different than the sealant condition that Ron described. We had NO sealant, just a THIN rubber seal between the inside of the frame and the Plexiglas. I guess its time for a FAQ here somewhere! Ron's right: "There aren't any articles in the past Mainsheets on replacing fixed windows that I'm aware of." Now that we're (or at least our boats!) all old enough, we get to blaze new trails!

Stu Jackson, Aquavite

I assume that you mean the fixed black tinted windows in the deck molding. If that's the case the job is quite easy. Remove the fastening screws. Ease the Plexiglas from the old sealant using a thin knife, fine piano-like wire or similar device to break the sealant bond. If you break a window don't worry too much you should be able to get a similar one cut, using the old one as a template, by any reasonably sized plastic supplier for less than about $100. Clean off the old sealant with a razor blade or sharp knife. Using a wide masking tape, tape all around the window frame both inside and out. Likewise for the window.

The old sealant line should give you a good idea of where to lay the tape edge. The reason for the tape is to keep the sealant off the areas around the window to make cleaning up easier. Gun the caulking into the window frame indented surface, in a continuous bead. Don't skimp, you want the whole sealing area filled. Carefully press in the window but don't push it in too the extent that all the sealant is squeezed out. You want the sealant to allow relative movement. Insert the screws but not too tightly. Wipe excess sealant off the masking tape before the sealant forms a skin. Depending on the sealant you use this could be a few minutes or up to perhaps ten minutes. Clean kitchen paper towels are good for wiping off the major excess. I prefer to use Sika's sealant cleanup fluid for the final clean up around the window, off tools and my hands. Sika's fluid is in a yellow bottle about six inches high. One bottle lasts me years, you don't need much. Remove the masking tape before the sealant skins over if possible. Once you've removed the tape don't mess with the sealant until it is completely dry, probably the next day. Use a sharp, hard back, razor blade, available from most hardware stores to trim any excess sealant. A word on sealants: don't be cheap, use a reputable marine brand like SIKA or 3M but not a household quality. There is a good reason the marine sealants are more expensive and its not just because they're for use on a boat, they are different. BUT DON'T USE 5200 for this application, you won't be able to remove the window the next time it has to be done, and it will have to be done. You've probably recognized from the above description that speed is important. Once you've applied the sealant work quickly but don't panic. There's no problem about cutting lots of excess sealant off its just time consuming. Go gently with the razor blades, you can easily cut the gel coat if you angle the blade too steeply. Best of luck on your first try. The second, third and later ones are much easier.

Charles Holder, Discovery