Pilothouse window seal leak

[stanfromhell]

One of my three pilothouse windows has began to leak at the bottom. Water has puddled on the dashboard as well as on a bunkbed belowdecks. I removed the rubber decorative trim on the outside and can easily access the edges of the glass where it is bonded to the cabin. I want to apply sealant to stop the leak and not pay to have a professional remove and re-bed the whole window. What would you recommend as a good cleaning product and and most importantly a good sealant that will stick to glass, the current sealant and fiberglass?

 

[SteveK]

I would use sikaflex 291 but look forward to other answers.

 

[BruceK]

This may not be your issue, but on a previous boat years ago,there were blobs of sealant applied inside to the windscreen windows attempting a leak seal. External inspection showed the rubber windscreen seals pulled apart at the joins creating a small gap allowing water entry. Pumping sealant into the gaps and smoothing off, sealed the intrusion and restored appearance.
In my innocence, I used (shock horror)a "Roof & Gutter" silicone sealant, it worked fine,( even takes paint) but 291 is probably better.

 

[SteveK]

Yes seal it on the outside, I did a year ago, no leak since. Yes it was the shrinking and gap at the corners.

 

[Comodave]

Sika 295UV might work. It sticks to plexiglass well.

 

[Bmarler]

If it’s not exposed to uv behind the trim you can use the 3m urethane. 3M 10.5 Fl Urethane Adhesive M8693
I’ve had really good results with it.

 

[ktdtx]

I had a leak lower port side pilothouse window..I used this stuff (or something close). I recall a blue bottle but the name sounds the same. It took a couple applications BUT..it actually worked.
Captain Tolley's Leak Stopper

 

[Andiamo2018]

If the window is old enough (or wasn't done right in the first place) to be leaking then all of the sealing / bedding is old enough to be leaking. A patch job can work for years but if you have the time and/or money it is worth removing the window and re-bedding it correctly. Then you know for sure if the leak is the seal around the glass or the seal around the whole frame.

What to use for the quick repair depends on what the type of material that makes up the window. If it is 'glass' glass then Dow 795 is the only way to go. If it is plastic, plexy or acrylic then 291 or uv4000 works.

Either way really clean everything with acetone and a green or brown scrub pad before applying new sealant.

 

[MV Moira]

I have used Permatex #81730 "Flowable Silicone Windshield & Glass Sealer" with success.

 

[drewread]

What to use for the quick repair depends on what the type of material that makes up the window. If it is 'glass' glass then Dow 795 is the only way to go. If it is plastic, plexy or acrylic then 291 or uv4000 works.

Why not use 3M UV4000 on glass?

"It is ideal for use on wood, glass, gelcoat and fiberglass as well as many metals and plastics, and recommended for topside components like hatches, portlights, metal hardware as well as porthole seals."
Source: -https://www.3m.com/3M/en_US/p/d/b40066991/

 

[Andiamo2018]

I learned about the 795 from Andy Miller at Boat Works Today. He is a great resource for all things boat. Apparently the stuff holds better than anything else to glass.

 

[Tjohn]

I second Capt Tolleys Creeping Crack Cure. For really fine hard to stop leaks it works after several applications. It goes on and looks like milk, it soaks in and hardens and then you add more after it sets up for a few days. I would add some each time I went out. It works, but best of all, no mess, no gooey visible sealant. For places where my rubber is rotted away or shrunk, I use black polyurethane gutter sealant. Silicones and anything called RTV is never used in my presence, period. (deep learned and deserved hatred)

 

[Carriem1102]

On our older Carver the rubber seals around the glass windshield had shrunk in the corners, causing the whole corner to be without a seal. We cut it back and applied some insanely goopy black sealant we got from a local car windshield replacement place. Cannot remember the name of the stuff but likely a Dow product. That was the toughest stuff to squeeze out and it got everywhere! But it sealed it all up nicely and residue could be cut off. Since that day last year i saw a video about a repair technician for RVs who was fixing exactly the same issues on RV windows and he swore by Dynaflex ULTRA for windows and siding. Same technique, but cheaper product and nowhere as near difficult to apply. So a couple of options for you. Since doing the front windshield i noticed the same issue with two side windows, so will try the Dynaflex on that.