Rebedding leaking windows

Pete the Cat

Sustaining Member
Either butyl tape or silicone will work. Folks have their preferences. The advantage of silicone (which is what most production boat windows were done with back in the day) is that it seals well and, if you carefully tape before you remove the window, can be cleaned up--but is wicked if you slop it around and it hardens. The advantage of butyl tape is that it never hardens and expands and contracts with the window better to maintain a seal. The problem with butyl is the stuff will expand goo out when it gets hot and needs to be cleaned up--but that is easy. If you get silicone around stuff, it is harder to remove. I always use butyl where there is predictable movement (like hatches and big windows and stanchions) and silicone when windows seem to be in places the boat is not going to flex. I like 4200 3m for windows because it has some adhesive in it, but would never ever use 5200 on anything that might need to be removed in the future. Some folks prefer no adhesive and just use plain marine silicone. You need a silicone that will stand up to UV, so some household ones will not work. FWIW.
 

bigd14

Contributing Partner
Blogs Author
You need a silicone that will stand up to UV, so some household ones will not work
Yes, do NOT use the standard silicone caulk for bathrooms and kitchens. The seal fails quickly and leaves a residue that is nearly impossible to remove and worse, doesn’t let anything else stick to it. Dow 795 is the only “silicone” sealant that I am aware of that works well for boat use. I used butyl tape (Bed-It is the only one worth using https://bed-it.com/) for port lights but others prefer sealant- 3M 4200 as Pete the Cat mentioned, or Sikaflex 291 are great, and I think some here use Boat Life. You’ll likely also need to replace the rubber gasket between the window frame and the glass or use Dow 795.

Do a search for leaking port lights there are literally dozens of threads on here about this job. Good luck with it.
 

stangc

New Member
A search for "Leaking port lights" yielded "No results found". I could use some help in how to remove the metal frame (on the outside of the port light) such that it can be reused.
 

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Prairie Schooner

Jeff & Donna, E35-3 purchased 7/21
Hi Stan (?),

I'm just doing a cut-and-paste of the links which were useful for me when I did this job last year. It's a barely edited data dump with my cryptic notes, but hopefully you'll find something useful.

master-thread.9603/
p4 #61- Butyl tape x2 #69- Butyl #70- 3M 4200 #75- yellowing of 4200 #76- Dow 795 & butyl #78- 3M 4000 and new glass vinyl



2022 vinyl bead source https://ericsonyachts.org/ie/threads/wanted-vinyl-glazing-for-fixed-ports-3-16-glass.19511/

#1 fixtures for clamping #2 soap for gasket insert lube #7 silicone grease or glycerin lube #9, #10, #13, specific gasket vendors #24, #27, #32 advocates for mechanical removal from molecular level #26 Silicone Solutions remover #29 DeBond and Remov-It worked well



#26 cleaning regimen, D795 instead of rubber gaskets, use special tool #34 No butyl, 4200 is too strong, instead 3 choices #35 4200 may damage some plastics



Bomar not rebuildable https://ericsonyachts.org/ie/threads/bomar-opening-port-lights-circa-1985.11670/


2005 paint frames veneer etc. https://ericsonyachts.org/ie/threads/opening-portlight-removal-and-replacement.2502/
2008-9 caulk v butyl
mostly cosmetic

#1- Smooth-On 01022 A4 Metalset


link for gasket co



Heat and Alcohol for sealant cleanup, esp when uncured

PORTLIGHT GLAZING VINYL

CUSTOM NEW PORTLIGHTS


If you're new-ish to the site, you might find @ChristianWilliams master thread list helpful. I couldn't find it just now, but someone will be able to direct you to it.

Cheers,
Jeff
 

bigd14

Contributing Partner
Blogs Author
If the port lights are currently bedded with 4200 or God forbid, 5200, Marine Formula Debond is the magical elixir. I find it intolerable to breath so take a good respirator if you use it.

I have had good luck using a straight blade on an oscillating tool to cut through the sealant but be sure to protect the cabin side from scratches.
 

mjsouleman

Sustaining Member
Moderator

[B][FONT=arial][SIZE=3]Prairie Schooner[/SIZE][/FONT][/B] gave you all the information you want to decide on what to replace and how to replace.


I did this several years ago and it was a slog. If I were to do it again, I would replace the current glass and frame with lexan.
The effort, time, and sweat just is not worth the price in my opinion, not to mention that the windows will leak again later.
 
The “quick hacky” option that “might work” could also be to just reseal the exterior trim. Did this over the summer with sikaflex and have had a drip free year so far.

a lot of this might depend on how much the legacy, interior frame sealant has held up. In my case it was maybe between 90-95% functional (the previous leaks weren’t gushing).

I can only recommend this if one doesn’t want to deal with the whole remove and rebed steps for fixed ports. But if it last a few years it’s pretty quick to do - in comparison. Your mileage may vary!

I justify this method by there being, what appeared to be a, “superficial” exterior caulk layer anyway. With some care and good taping it turned out neat.

use your discretion as this method is not one-size-fits-all; I chose to remove and properly recaulk the foreword hatch.
 

vanilladuck

E32-3 / San Francisco
Blogs Author
Re: Dow 795, I'm getting closer to bedding new portlights on Rumour. When I cut out the old portlights, most of them were bedded with silicone, at least one of them looked like it was rebedded with something like Sikiflex. From what I know of silicone, it penetrates and cures to the gelcoat on the outside of the boat and is very difficult to remove entirely (even if you can't actually see it). Do I need to remove it entirely before using Dow 795?

If so, will Anti-bond or Marine Formula Debond work to remove the silicone I can't see?
 

Kenneth K

1985 32-3, Puget Sound
Blogs Author
If so, will Anti-bond or Marine Formula Debond work to remove the silicone I can't see?
I don't know the actual answer, and I've not yet done a window/port replacement. What I've always read is that silicone seeps into the gelcoat so that nothing else will bond well to the gelcoat in that area--it can't bond to the silicone that soaked in. I have no idea how deep this seepage can actually penetrate the gelcoat, but I'd probably feel better rough-sanding (60 grit) the gelcoat rather then using de-bond. You could sand all the way to the fiberglass. But even if you didn't, sanding will remove some of the slick silicone layer and the added roughness will give the next sealant something to grip onto.
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
I'd say remove as practical but not worry a lot. I don't think adhesion is very important with portlights, the typical caulk acts more like a gasket, and there's a big flange area for coverage. The portlights are held in place (lightly) by the interior frames, but all forces come from outside.
 
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