Port Light Gasket Adhesive

[Gazoo1000]

I am replacing the gaskets on my port lights.

Many boaters reccomend using 3M UV 4000. However, this products comes in a 3 ounce tube. I can't imagine this is enough of the stuff for even one port light. Am I missing something here?

Gazoo

[Bowdrie]

Dap/Weldwood contact cement.

[Gazoo1000]

Thank you for the reccomendation. Can anyone share the best way apply this stuff. I'm thinking I should use a tiny paint brush (the kind a professional artist uses on canvas).

Thank you in advance!

Gazoo

[Bowdrie]

Go to Harbor Freight and buy a 36 pack of throwaway acid brushes for $3.

[Boogie]

I just did mine.

This is what you want:

https://www.oreillyauto.com/detail/c...E9itcTK1mSaDoi

[Gazoo1000]

Originally Posted by Boogie

I just did mine.

This is what you want:

https://www.oreillyauto.com/detail/c...E9itcTK1mSaDoi

Thank you for the reccomendation but I see a page that says "Page not found".

[jigray3]

I chose Bed-it butyl hybrid tape, and couldn’t be happier with ease of application and results. However, my portlights are mechanically attached with screws, so what I wanted was a bedding sealant, not an adhesive. When installing anything, I always imagine what it would be like to remove it to repair or replace it later.

The hardest and most time consuming part of replacing 8 Portlights was getting them out and removing every bit of silicone based adhesive sealant the manufacturer used. Solvents would not do it. It took scrapers, plastic razor blades, and abrasives.

At one point I needed to remove one of the portlights I had installed a few weeks later. Required some effort, but didn’t lift gelcoat like the adhesive, and cleaned right up with white spirits in about 1/5th the time.

[Greatest Lakes]

Depends on the mounting style, Newfound metals for instance uses an external ring that demands both butyl tape and an extra sealant to bed the fixture watertight.

[Bowdrie]

Maybe we should find out if the OP is mounting new gaskets to seal the opening part of the portlight, (my take on his question,) or using gaskets to seal the mounting of the portlight against the cabin side(s).

[wholybee]

To clarify, when you say "gasket" are you talking about sealing the frame to the hull, or the rubber/foam gasket for the opening acrylic window to the frame?

For the frame to the hull, 3m UV4000 comes in a 10 Oz tube that loads into a caulking gun, and that is what you would want. It will do several portlights.

For the foam gasket, Cyanoacrylate.

[CarlF]

Assuming this is to attach the port to fiberglass - If window is acrylic/plexiglass use Dow 795. If bolted metal frames, use BedIt Butyl Tape. Don't use butyl sold for RV's, auto's or houses.

If using BedIt, it's critical to go back and tighten the fasteners another 1/4 turn several times over the next days or weeks. This is what makes the butyl "flow", giving you a 40 year seal.

https://bed-it.com

If using Dow 795 make sure the caulk is not compressed too thin. Keep it at least 1/4" thick. If necessary use 1/4" foam weatherstripping tape to hold the window off the fiberglass by that much while the 795 hardens. This is what allows the caulk to stretch as the window expands and contracts with sun heating. If it's thin it will eventually rip free from the expansion movment. Do not use Dow 795 past the tube expiration date.

[Locquatious]

We had great luck with just clear silicone caulk. It adheres well to glass and is easy to razor blade off the excess.
When assembling, if the port lites have a frame that is screwed in to retain the glass, don't tighten the frame completely. Leave about 1/16" looseness until the caulk hardens. Then tighten. That's what they mean by form a gasket.

[jigray3]

Originally Posted by Greatest Lakes

Depends on the mounting style, Newfound metals for instance uses an external ring that demands both butyl tape and an extra sealant to bed the fixture watertight.

I saw them at the Annapolis show 3 years ago and they were using closed cell foam adhesive backed tape. They sell that and the butyl tape on their website.

[Boogie]

Originally Posted by Gazoo1000

Thank you for the reccomendation but I see a page that says "Page not found".

Hmmm, dunno.

the link works for me.

But google this:

3M 5 Ounce Weatherstrip Adhesive - 8008

Many sources to buy.

[s/v Jedi]

Boogie got it right. This is the best adhesive for the job.

https://www.oreillyauto.com/detail/c...E9itcTK1mSaDoi

His mentioning of a liquid sealant is puzzling though and he indeed may not be installing new gaskets at all.