What window caulk to use?

[SVLydia]

I am replacing the side windows in my Telstar 28 trimaran. Can anyone suggest a good caulk to use?

The current windows are caulked and then screwed into place. The windows are all flat.

I am not experienced at this type of project, so any advice is welcome!!

Thanks!

[thinwater]

Originally Posted by SVLydia

I am replacing the side windows in my Telstar 28 trimaran. Can anyone suggest a good caulk to use?

The current windows are caulked and then screwed into place. The windows are all flat.

I am not experienced at this type of project, so any advice is welcome!!

Thanks!

VHB tape and Dow 795.


Google instructions.

[Marathon1150]

I use marine silicone to seal lexan windows held in place by a bolted through metal frame. This is the recommendation from Don Casey in , This Old Boat. I replaced all of the non-opening lenses in 2018 and everything is still water tight despite living in Mexico and French Polynesia for several years each.

[Tupaia]

If they are frameless windows consider not using screws at all, these are the primary causes of leaks.
Be sure to prep the contact surfaces of the lenses, light sanding to produce a good key. Be absolutely scrupulous with cleaning the mating surfaces, then mask carefully and apply silicone evenly to "both" surfaces before making contact. Ensure there is sufficient thickness to facilitate expansion.

Tip; if there are multiple lenses next to each other then a foam bead should be used to compensate for any expansion causing 3 dimensional stress on the silicone joint. Here is an example but ignore the structural spacers.

https://media.licdn.com/dms/image/C5...Y3OXVVWj2xG1sw

[Hesti]

As mentioned above by others, the caulk and preparation itself is just one aspect but the thickness of the caulk between window and grp is very important for how long the joint will last. I have done the job once and I actually used spacers taped to the window that were resting on the grp with their tip for say 2 mm to ensure joint thickness. If I remember correctly, I went for 3 mm joint thickness (1/8 inch) or so. Also, there was a foam tape to stop the caulking from going too far into the joint and coming out inside the boat.