i am redoing the seals on my American 21 cabin windows. They originally had silicon around them and were riveted straight to the fiberglass cabin. It is basically a plexiglass style piece riveted to the boat with no frame. The silicon was good but the rivets were leaking so I pulled the window. I was wondering if butyl tape would be better than silicon.
Fixing seal on sailboat windows
- Thread starter Armyaviation
- Start date
Armyavaiation;
There is a specific type of sealant that most manufacturers use and would suggest that you use that vs. silicon. If anyone is looking at this I believe it is a GE product but may be wrong. Regular silicon on windows does not really hold nor would advise that. Not sure about the butyl tape but most mfgs. go the other direction.
There is a specific type of sealant that most manufacturers use and would suggest that you use that vs. silicon. If anyone is looking at this I believe it is a GE product but may be wrong. Regular silicon on windows does not really hold nor would advise that. Not sure about the butyl tape but most mfgs. go the other direction.
Great article: http://www.sailmagazine.com/diy/ask-sail/replacing-fixed-portlights/
The 795 is perfect but ya have to use some spacers to stand the glass off to create a consistent thickness. Some folks have used a "tape" version of the same stuff used to glue windshields into cars. In all cases, the plexi must be held in place until the glue cures.. Folks have used sandbags, wood clamps, ropes, etc..
The 795 is perfect but ya have to use some spacers to stand the glass off to create a consistent thickness. Some folks have used a "tape" version of the same stuff used to glue windshields into cars. In all cases, the plexi must be held in place until the glue cures.. Folks have used sandbags, wood clamps, ropes, etc..
I have the 795 in my tool box but went with the Butyl Tape for ease of installation. The only issue I had was when I would accidentally touch two pieces of tape that I did not want touching. Other than that, a good seal was made and minimal cleanup was needed. I waited about a week after affixing the port trim before trimming the oozed out tape.
......................... which of course is silicone (much to the dismay of boating purists everywhere).
To hold the acrylic in place while the 795 is curing, Marlowe Hunter uses small wood screws. Once it's cured, the screws are removed and the holes are filled with 795. On our boat, you have to be up close to see where the holes have been plugged.
As kloudie mentioned, be sure to use some form of spacer such as 1/8" adhesive backed foam tape to ensure a constant thickness of silicone. Anywhere the silicone is too thin and allows the acrylic to touch the FG cabin, you run the risk of not allowing for thermal expansion of the acrylic relative to the FG.
No screws! I'm a monumental skylight designer. You are talking about a strutural glazing joint. Use 1/4x1/2 3M VHB tape set 1/4" from the edge. Mask all surfaces, motor in the DC 795 and tool the joint. Pull the taoe imediately. The result will be a structurally sound, water tight jount with no screws, plus it will look like a factory rubber gasket. I've posted real instructions a few times if you search my posts. There was also some jerk that totally outclassed me and posted some really nice instructions, with pictures. I'll have to do a video with a pretty girl in Daisey Dukes.
.......................... yes, as long as there's no curve to the surface the acrylic is adhesing to. All the ports on mine have a slight exterior curve except and the most forward one has a good curve to it. It has permanent, black screws in it (in oversized holes).
I used the Sail mag article to replace my fixed portlights. They had been screwed into the sides of the cabin, and then the gelcoat spider cracked over the years, until the crack ran under the sealant and out to exposed gelcoat. Then water could get through the crack, under the sealant, and into the screw hole to drip inside. I've been happy with the VHB tape, it hasn't let go after 2 seasons. You'll really have to work to get the contaminated gelcoat off. I cleaned mine with goof off professional, which is manly some kind of petroleum distillate solvent. Then, I sanded the gelcoat to get the silicone contamination off. Resealed with Dow Corning 795. The boat looks really slick without any screw heads in the plexi. I think the article recommended painting the plexi with silicone based paint, which I used exhaust paint. However, I think it would be better to use some form of acrylic paint to paint the acrylic plexi - but I wasn't able to find an acrylic paint that seemed to be exterior.
Curve has no effect. My cabin is curved in several directions, The VHB will hold better than the screws plus it won't create stress risers that will cause spider cracks working outwards from the screws. Screws are old technology. Might as well drive in oak dowels.
+1 for the VHB/ Dow 795. Just take whatever time is needed to prep the surface and remove all the old silicone or adhesive the previous owner used. Just remember with the VHB tape, if you don't get the window in the right place on the first try, it's not coming off.
I hot glued 3 positioning blocks onto the side of the cabin, 2 along the top, 1 on the back side. They were about 2" tall. It allowed me to line up the window against the blocks, then slide along the blocks until contact with the cabin. Perfect alignment, because there are no do-overs with the VHB tape.
With the VHB, leave the paper on except for a couple of key spots. At those locations, fold the paper so a tab hangs outside the glazing. Once you have it positioned, slowly pull the tape out and set the glazing at the same time. Put a rag over a rubber mallet and beat around the perimeter a bit to get rid of bubbles.
+1 on the 3M VHB adhesive tape... This is what I used when replacing my portlight windows with Lexan,... I used silicone adhesive after installing along the edges for waterproofing... I pressed the Lexan against VHB with a wooden roller but protecting the Lexan with painters tape to avoid scratches... did this last year and results are still looking as good as when I installed them. The VHB tape and 1/4 inch Lexan did the slight curvature of the side deck just fine, no issues. I have photos and will dig them up. Here is the video I used when figuring how to use the 3M VHB tape.
Armyaviation - did you reset your windows yet? My brother just got an American 21 and I think they are through-bolted rather than riveted - possibly replaced by Previous Owner (PO)? Will check on this in the next couple days - maybe get some pics of the rudder set-up eventually,but he has some repair work to do on it.
I did one side using exterior silicon that was black color. It was thick so I applied around window, after masking, and applied even pressure. As it set I could see through the window the silicon spreading out. I used two pegs to hold window up in location. I did not want to reuse rivets because it's another place to leak. Worked great
As for it not holding or the window popping out, have you ever tried to get silicon off something?? That window isn't going anywhere anytime soon