Caulk It!

Stationary Salon Windows Replacement Procedure Summary

C320 Association Technical Editor Chris Burti

With the ageing of many of our hulls, the oldest approaching 24 years, acrylic lenses and sealants may be reaching the end of their lives, so this is a project that may interest many of us. Special thanks to Dave Hupe for submitting this article. –Warren Updike,

I purchased my 1994 Catalina 320 (hull #32) early during the spring of 2017. At that time the boat had several leaks including seepage from the forward, port side stationary salon window (fixed portlight,) above the navigation station. The various boat manuals that had been stored in the navigation station were mildewed and pages stuck together due to repeated water leaks. It wasn’t long before the aft, port side salon window also started to leak. These original window lenses were both screwed and sealed in place (Catalina has since stopped using screws, just sealant) and there were numerous cracks around the mount holes as well as general scratches/crazing. I determined that it was well past time to get serious about replacing all four salon fixed lenses to stop the leaks and for aesthetics. 

I contacted Catalina Yachts in Florida for replacement lenses, since I could not locate someone local to provide lenses as rapidly as desired. Since my boat had been originally manufactured in California, Catalina was not sure about exact lens sizes. Therefore, they requested tracings of each window be sent to them which they would compare to existing lens patterns. They indicated that if my tracings matched their patterns they would use their patterns. Otherwise, they would cut lenses to match my tracings. 

I made my tracings by taping good quality rolled paper tightly over the in-place windows and using a pencil to trace the sharp window lens edges. Catalina then wanted me to cut out the shapes carefully before mailing them to Florida. 

The lenses I received from Catalina did not match my tracings as well as anticipated (I had made/retained duplicate tracings that I was able to use for comparison). However, I still was able to install the new lenses satisfactorily. The sealant used (black Dow 795 recommended by Catalina) accommodates a lot of variability regarding the fit of the lens. This sealant is very flexible/rubbery and resilient for this use. Two of the lenses were slightly large for the window openings. In this case, the lenses “stood proud” of the window recesses and the resulting finished outer edge seals are thin, but the sealant behind is thick. In comparison, finished sealant edges/borders are wide when the lens is small for the opening and sits down in the recess. The lenses from Catalina are beveled inward on the edges to match the window recesses. The bevels are cut at about at a 30 degree angle. However, it is not just a straight angle. An outer butt edge and then a recess is left to prevent chipping of what would have been a sharp edge if not for the intentional butt edge. My original lenses had just straight 30 degree beveled edges.

Below is my step-by-step outline of the procedure I used:

1. Prepare braces that will be used to hold the new lens in place (primarily to hold pressure on the front and rear ends to maintain the slight inward window bow/curve that occurs when set in place while the sealant partly cures). The lenses are flat, not curved when received. These braces can be made simply/inexpensively from lengths of 2x4 wood slightly shorter than the lens and 2 end “feet” of 2x6 wood (about 6 inches high) screwed in place. I used furniture leg pads with rubber bases screwed to the outer 2x6 edges to help prevent the braces from slipping on the lens protective paper when clamped in place, and also concentrate pressure on the outer corners. When set it place, these braces will allow you to work completely around the perimeter of the new lens to remove excess sealant and smooth it just after placement. Also, the tape around the opening can be removed without unclamping the brace. The brace can be held in place/pressured with a single ratchet strap clamped to the handrail above the window and the jib car track block (slid where necessary to put good pressure on the window lens). Figure out this placement on the old lens before removal. Other methods of holding pressure on the lenses (as recommended by Catalina) can include weights hung by rope from the handrails above the windows, or wedges held in place somehow. Another procedure recommended by Catalina involved Duck Tape and wood wedges…..I suggest DON’T use this unless you want a big chore removing the tape residue later. I made 2 braces so that I could work on several windows simultaneously ….. one brace for the front window and another for the rear window. The rear brace needs to be longer to span the lens sufficiently and pressure the outer ends. Also, specific feet on the braces will need to be attached at an angle to match the front or rear ends of the window lens. Work this all out on the old lens while still in place.

2. Cut plastic sheeting to tape inside the cabin around the window opening to collect associated dirt. Tape it first below the window and ready pieces of tape to eventually tape it above the window and on the sides.

3. Remove the original window lens mount screws on the outside and run a utility knife around the lens perimeter to cut/loosen the sealant. Be careful not to cut the fiberglass of the window opening/recess…..slant the utility knife blade inward toward the lens center.

4. From inside the boat, push on the lens edges to begin dislodging the lens. Once the lens starts coming out, finish taping up the protective plastic sheeting inside the boat over the window opening to keep the inside clean. It will then take pulling carefully along the lens edges from the outside and inserting a putty knife behind the lens to gradually remove the lens. Others have suggested using monofilament line in a sawing motion behind the lens to gradually cut the old sealant. Be careful as the lens may break. 

5. Once the lens is removed, scrape the old sealant away from the window recess. The old sealant should peel away fairly easily. Continue to scrape, vacuum, and clean with acetone to remove as much of the old sealant as possible.

6. Sand the entire window recess that the new lens will adhere to (but not the inner “window sill” of the window opening) with medium to coarse sandpaper, vacuum, then clean well again with acetone (including the “window sill” area). From outside also vacuum out the debris that has collected in the plastic sheeting “pocket” covering the inside of the window opening.

7. Tape the outside edge of the window recess using easy-release painter’s tape.

8. Without removing the protective paper on the new window lens, dry fit the new lens in the opening. Use sufficient pieces of painter’s tape to temporarily hold the lens securely in your desired best fit position that will optimize the seal entirely around the new lens.

9. On the outside perimeter painter’s tape and the outer edge of the protective paper on the new lens, mark several sets of alignment line reference marks. Also, temporarily untape the plastic sheeting inside the boat and tightly trace the window opening outline with a pen on the inside protective paper. 

10. Remove the new lens and tape the entire inner “window sill” opening with painter’s tape. Also, tape the plastic back up inside.

11. When taping the perimeters, run the tape in one direction and leave a loose tab so that the tape can be removed in one clean pull when desired. Use consecutive small tape pieces taped across each other to make rounded corners. 

12. Leave the outside lens protective paper on until all work is completed! However, on the inside of the lens, cut carefully/completely with a sharp utility knife blade along the line that was traced on the inner protective paper (matching the inner window opening).

13. Pull off the protective paper from the inside of the cut line (exposing what will be the clear lens view area inside the boat). Then carefully tape back over this cleared area with strips of painter’s tape that can easily be removed after the window is set in place with the sealant. Again when taping, run the tape in one direction and leave a loose tab so that the tape can be removed in one clean pull when desired.

14. Remove the remaining thin strips of original protective paper on the inside of the new lens (this will be the ultimate mounting surface primarily about 1 inch wide, but also will be nearly 6 inches wide on the starboard side lenses where the lenses span bulkheads), then sand the exposed edges of the lens and exposed flat lens surface with medium to coarse sandpaper to prepare a good bonding surface. Lastly, clean well with isopropyl alcohol (not acetone) to remove sanding dust residue and any grime.

15. Get ready plenty of paper towels, a garbage can, and some plastic putty knifes and acetone. 

16. Have available a minimum of 1.5 - 2 caulk tubes of Dow 795 black sealant and a good caulk gun. 

17. REMEMBER as you prepare to apply the sealant…….for a good job, more sealant is desirable as opposed to insufficient sealant (even though it will be messy during the process) !!!!

18. Get the ratchet strap ends in position/ready (although kept sufficiently away from the window opening) and the brace nearby.

19. Apply sealant quickly/liberally to the entire window recess with a caulk gun, being careful to provide a smooth and thick surface. Pay attention earlier in this process (step #8) to how the lens dry fit initially (determine earlier if the lens will “sit proud” in the opening, in which case a thicker seal will be needed underneath, or will the lens sit down well in the opening in which case less sealant will be needed?). Make sure when applying sealant to extend outward (close to the outer window recess) so that the new lens edge seats well in sealant. Just before placing the lens you can quickly smooth the sealant with a plastic putty knife ….. being very careful not to reduce the thickness of the sealant. Note – you can’t pull the lens back out if at the last second you realize you used too little sealant. Remember again….more is better than too little!

20. Carefully/slowly place the lens in the opening, using the alignment reference lines on the protective paper and outer ring of painter’s tape as guides. Push the lens firmly into place….the sealant should “grab” the lens pretty well. However, don’t push so hard that the sealant squeezes out too much until the brace is in place to hold steady pressure on the lens/sealant.

21. Carefully install the brace over the new lens and tighten the ratchet strap, being careful not to disturb the alignment.

22. Quickly clean excess sealant away from the window edge and edge of the painter’s tape surrounding the window recess with the plastic putty knife and/or smooth carefully with your finger tip. Don’t overdo it ….. and do this quickly, since the sealant will start to skim fairly rapidly. If the lens is loose for the opening, don’t push hard/indent with your finger around the edge (leave a good border of sealant to achieve a fairly flat blend from the new lens edge to the gelcoat of the window opening). 

23. Go inside the boat, remove the protective plastic, and clear excess sealant/smooth tightly around the inside edge of the window with your finger (while also pushing excess sealant into any open spaces around the inside edge). 

24. Go back outside and carefully remove the painter’s tape surrounding the window opening before the sealant starts to cure too much. Don’t pull up/out…..pull forward/parallel with the gelcoat surface to get a good clean break. 

25. Remove inside painter’s tape in the same manner. 

26. Allow the sealant to cure at least a full day (better …. two days) before removing the outside ratchet strap and brace.

27. Carefully lift a corner of the outside protective paper with a utility knife blade and pull off along one edge at a time slowly (also pulling parallel with the window surface, not outward/up to avoid pulling the seal too much). Carefully cut the paper/sealant interface, if needed, with a razor blade (sliding the blade flush with the window face). 

28. DONE (except for maybe a little careful wiping with acetone if there are any small smears of sealant).

This took me the better part of a day per window. –Dave Hupe, 1994 Catalina 320 (Hull #32) – Mayan Sun, Holland, MI

End Note: On our Association Web Site,, search “portlight” to find “Portlight-Window-Replacement Documentation” that Catalina provided. There are two pages, one from 1983 and one from 2014. Here they recommend using duct tape with wedges to press the lens. Dave’s approach using wood braces makes it easier to complete the steps with the braces in-place. Note that there are additional photos available for this project by sending an email to Warren Updike at


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