Window resealing

[Bill Roosa]

I am trying to reseal the HUGE fixed window on my Legend 40.5 the "skylight" is made of Lexan and my attempts to fix the leak with 5200 have only resulted in the exact same leak again. I saw in a recent post that 100% silicon was the recommended sealant for lexan but have also heard that silicon has no place on a boat. I personally have found that where others (POs) have used silicon on Gelcoat it does not stick for very long and I have had to go in and fix it with something else. the skylight seems to be expanding and contracting with temperature and that is what caused it to pull away from the 5200. i didn't even think 5200 would let go like that but it has clearly separated from the lexan cleanly.

What is the recommended sealant/adhesive for lexan to gelcoat?

 

[Don S/V ILLusion]

My trial and error experience

Bill
I won't bore you with the long story how I know this but suffice it to say I can empathize with your project.

The only thing I found which has worked well is Dow Corning 795.
It is a structural silicone used to bed windows in commercial buildings. I used it to rebed this window after trying various other folks' favorite products and after 4 years, it is holding well. It's relatively inexpensive and comes in several colors and readily available at any industrial building supplier.

Silicone, to my knowledge, is the only sealant that's compatible with acrylic.

If you decide to go with the Sika 295, be sure to use the primer as it won't stick without it. I learned this the hard way too.

 

[Bill Roosa]

A man with an experience is.....

never at the mercy of a man with a theory!!!

Thanks Don

 

[Steve Dion]

Bill, I have used Dow 795 with great success.

Bill:

The large windows that Hunter has on these boats have used Dow 795. You can purchase it through industrial supply houses. It is a commercial product that is used to glaze windows on sky scrapers.

I had a minor leak on one of these large windows on my Hunter Vision 36. I cut out a vertical section and cleaned it up with some alcohol and a scraper. I masked off the area with tape and recaulked the area without much ado. I used a putty knief to smooth it you and finished it with a finger. The surface sort of smoothed itself out.

We also used this product to rebed the entire window/skylight on a Beneteau 34 and there have been no additional leaks (2 years).

I believe that we purchased the charcoal color. The place that I got the material was charging something like $5-6/tube.

Good luck on removing the 5200. I suppose you could have picked a worse product for this repair but I don't know what it is. I hope you can get all of the stuff off/out without damaging the window.

If you remove the entire window, I suggest that you place some of those small stick on silicone bumpers around the edge of area to prevent you from squeezing out all the material when you reseat the window. Place some sand bags or heavy weights on the window while it is curing.

We will be interested in knowing how this project turns out.

 

[Bill Roosa]

It is not stuck to the window Steve!

I've heard that 5200 is "permanent" and getting out is a real pain but the stuff is certainly not sticking to the lexan. I can push on the window from the inside and see it lifting off the 5200!

I believe I can say with confidence that your assessment that 5200 is THE WORST for lexan is "balls on accurate"

It should be no problem getting the window out. Once that is out of the way I'm hoping (yea, I know hope is not a method) that I'll be able to get some real elbow grease to the 5200 in the window recess.

I'll let you all know how it goes.

 

[Deadline]

At the end of the project...

Run a thin bead of LifeSeal clear caulk around the port. Clear disqguises any errors or slips, compared to white or black. LifeSeal holds up fabulously and may solve your problem in the first place.

 

[Paul Cossman]

5200 remover

Bill, I have used 5200 remover and it works very well. I just did a quick google search and came up with this link for a description and place to purchase it. http://www.dealtime.com/-3m+5200+remover. It worked like a charm for me on my non-skid fiberglass where 5200 had been used.

However, when I removed and replaced the large windshield on my P42 I found it was pretty easy (although tedious and time-consuming) to scrape out the old Dow Corning 795. I put in the new one using the Dow Corning 5200 about 8 years and many miles ago, and still no leaks or problems.

 

[Steve Dion]

Attn: Bill R

Bill:

If you look at the West Marine catalogue or other material compatibility source you will see that acrylic/lexan is Not Compatible with 5200. This is probably why the window did not seal.

The question will be how much work will it be to R/R the 5200 from the fiberglass/gel coat.

I think you will be pleased once you get this cleaned up and re-bedded.

 

[VT Fitz]

Silicone = Gasket, not Adhesive

My understanding is the silicone is creating a customized gasket, not providing a sealant, per se. Fasteners provide the hold; silicone keeps out the water.

Yes, I too have read 5200 & lexan are a no-no...