New Member with leaking GB42 cabin window.

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Dec 26, 2017
Vessel Name
Red Eagle
Vessel Make
1995 GB 42 Classic
I am the owner of a 1995 GB42 Classic which we keep at Whitehouse Cove Marina in Poquoson, VA. We took “Red Eagle” around the Great Loop in 2015 and are planning the Downeast Loop this year.

I am currently replacing a leaking window in the aft cabin head. I have removed the exterior teak trim, the moveable and fixed glass, and the window track. The new track and glass are on order, but I don’t know what type of caulk to use to glaze the fixed window to the teak exterior trim and to seal the exterior trim to the fiberglass and track. The caulk I removed to get the window out was white, paintable and still flexible after 22 years. Looking for something similar.


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buytl tape
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I used buytl tape and sikaflex last week to mount 2 new windows. It took 3 days to tighten really tuff stuff.

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Redis my aft cabin window caulking using sikaflex 291 LOT. No a leaking drop since and we are ranging from -35 to +35 celsius during the year. Not difficult to apply but keep a pile of rag nearby. If you put some where it should not go use WD40 cleaner degreaser or some spray nine to easily remove it.

Your windows were bedded with dolfinite, probably. That was the go-to caulking compound for GB in its day but eventually, like all good things, it goes south. Dolfinite works but is hard to find and is unfashionable like red lead (although there is nothing anti-human in it). I, like others have stated, have started using butyl tape for everything that needs sealing (except for oil and fuel). Its easy to use (unless it contacts itself!) and comes in different widths and black or grey. Buy it at a glass shop and get lots for all the other stuff you will use it on. Use the wide stuff for hatches and large areas and the narrow for small stuff. Kinda obvious but it might save you another trip to the glass store.

Pick a glass shop because they have to stand behind their work and won’t buy crappy supplies like buying it on eBay.

Some of the tape will ooze out under pressure, just cut it and peel it and plan to return later to check any fasteners you have tightened.

It also sticks to your clothes and your skin, just like poop to a blanket so be prepared to wear the proper old clothes and gloves.
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I found buytl tape at a local RV store. Worked real well when I had to do a hatch on my old Aquarius. Nice to use and seals real well.
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Compass Marine carries its own butyl tape that other TFers have tested and love
I bought and use COmpass Marine's tape. Have to buy more this year.
I own a 1974 GB 36 and rebedded with Dolphinite. Tried butyl tape but it did not compress to seal as well as the Dolphinite did. Consistency is like very thick sticky peanut butter. Take your time when applying it and it squeezes out nicely to ensure a good seal.
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Hello Sax,

Step one, go to the Grand Banks Owners Resources site and join if you haven’t already. Grand Banks Owner's Resources

Here are some links I have bookmarked for when I did this project for those considering doing the same.

Here are some links I have bookmarked that will help you I think.

This is a good set of instructions from Marin.

Take your time and you will be happy with the finished product.
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