Bonding windows in trawler

[Scratchy Dan]

Does anybody have experience in bonding windows into a plywood cored wheelhouse side? I'm currently doing a major refit on a 41' trawler and am considering eliminating the teak windowframes, which always seem to be a major source of leaks. I am planning on routering out a rebate of about 1/2" by 7/8" to bed the glass in then using a design from Sika's website I'll bond the glass in. Does anybody have good/bad reasons to do or not do this? Any tricks I should know and lastly should the glass be installed from the outside or the inside?
Thanks
Dan

[Eric Sponberg]

Sikaflex is not necessarily the best bonding agent. First, the windows should be installed from the outside, against a frame from the inside. If you use glass, I recommend laminated glass, although many people prefer tempered glass. Tempered glass is a lot stronger, but if it breaks, it shatters into a million pieces. Laminated glass will crack and craze, but it will always remain in the frame.

You can seal and bond the window into place with either Trade-Mate glazing sealant by Dow Corning, or Ultra-Glaze by GE. Both are silicone sealants specially made for glass. Be careful of using Lexan or other polycarbonates--the surface may need special preparation.

Eric

[Scratchy Dan]

Thanks Eric,

I'll have a look around for those products. I don't know if they are available in Hong Kong, some things are and some are special order only.

I plan on using laminated glass, for the reasons you suggest. One further question is UV protection. The boat will be in the tropics where it really knows how to rain and when it isn't raining the sun beats down very hard, not to mention some days with really nasty air quality. How UV resistant is silicone.

The logic on the Siika web site with UV protection seems pretty good but they are trying to sell product not get the best result.

Thanks for your input.
Dan

[Eric Sponberg]

As far as I know, the UV protection of these silicones is very good. I believe we used Trade Mate on a 65' sloop back about 6-8 years ago, and I have not heard of any problems with it. I stay in touch with the owner regularly and he has not mentioned it.

Eric

[Scratchy Dan]

Thanks Eric,

I was in the hardware disctrict in Hong Kong today, no home depot here. I was advised by one shop that Sika was not the best choice, plus I can not get their UV sheild here either, so that really counts it out. I noticed several shops with Dow silicone but none had brand names, all have numbers. Is the Trade Mate also marketed with a product number? One supplier claimed that the best product is Sonolastic Ultra by Degussa. This is a polyurethane sealant. Any comments?

[Eric Sponberg]

The full names of the sealants are "Trade Mate Silicone Glazing Sealant" and the other is "Ultraglaze Structural Glazing Sealant". There are no product numbers attached to the names.

I don't know anything about polyurethan sealant. One other source you might check, however, is what to the car repair shops use to seal the windshields of cars. I feel certain that would work.

Eric

[J Ralph]

dan i just put new windows in my 47ft wood dragger the way you are talking about.I rabbited out three quarter inch plywood,epoxied the rabbit with west system resin and used a urethane cement that they use for car windshields.I will try to find the name of the product,but any glass shop should be able to tell you what to use.after you bed the glass with the urethane,seal the outside with a good silicone sealer...good luck

[Scratchy Dan]

Thanks for the info Ralph.

Have you tested the windows with a good strong hose yet?

I'm almost to the stage where I'll be cutting out for the windows. It will take about a week to get the laminated glass done and then I'll be testing out the polyurathane and silicone. Or silicone only

Cheers,
Dan

[J Ralph]

I have not tested the windows yet,but the guy at my glass supplier said the only way the window would ever come out is in pieces.as far as silicone goes,I think thats just for waterproofing,the urethane is the "cement" or glue that actually holds the glass in place.It comes in a metal tube just like a tube of caulking.the glass man recomended that I heat the tube up to make the urethane flow easier out of the caulking gun(and i think it helped it to set up faster)hope this helps

[Scratchy Dan]

Thanks for the info. I've ordered the glass, but still have a bunch more work to do before I can install it.

This might be a good thing as I have not been able to find a supplier who can do frits for me. That's the UV blocking material on the inside of the glass.

Did you have frits or some UV blocking material installed on your glass? If you didn't how does it look. I'm concerned that the glue joint and any blocks I use to position the glass will be visible. It might not be the best looking installation.

I've checked with Sika, they don't bring their UV flim into Hong Kong.

Any suggestions.