Sealant for acrylic windows

[Jasetheace02 9]

I am fitting new acrylic windows and have some sealant which is Prosil 10 from Burnsco. Would this be suitable or would something like Dowsil 795 be better? 

I only want to do this job once!!!

Cheers.

 

IMG_1658.HEIC

[marinheiro 364]

Your Prosil should be ok, key is that it is neutral curing - some bathroom silicons are acid curing.

[Bradz 20]

+1 for the Quilosa

[ScarecrowR31 8]

Im with lateral. VHB has added bonus of nice interior finish. BUT...as Sabre points out depends a little on type of window  surrounds and fixings (if any)

[Jasetheace02 9]

Thanks for all the suggestions, I feel there are probably several good products that will do the job. I am sure whatever I use will be 100 times better than what was there, looked very old with several different products used for repairs over the years? I will try and attach a photo.

Basically a recess that the window sits in and then the moulding with screw holes goes over top. 

[Island Time 1,293]

If you use a decent adhesive/sealant (like mentioned above, I use and recommend Quilosa MS35 from the glue guru), you can forget the frames and the screws. Fill the screw holes and paint. Stick the windows in with the adhesive, good to go.

[Jasetheace02 9]

58 minutes ago, Island Time said:

If you use a decent adhesive/sealant (like mentioned above, I use and recommend Quilosa MS35 from the glue guru), you can forget the frames and the screws. Fill the screw holes and paint. Stick the windows in with the adhesive, good to go.

Yeah I have read about this option. It makes me a bit nervous to be honest the I like the idea. Some of the moulding screws have stripped also which means I would have to fit through bolts so the adhesive only option would solve that. 

I feel I would still need to fit the moulding though to cover a gap between the outside edge of the window and the edge of the recess? Maybe just fill in and paint the countersunk holes in the moulding?

[Island Time 1,293]

The is no need for the bolts/Screws, they are what eventually leaks. You could fill the holes in the frame, stick the windows in, then the frames on top for purely cosmetic reasons if you want. Modern adhesives are stronger and more flexible than the initial fixing and sealing system. Most modern boats have windows fixed without mechanical fastenings now, and the joint is usually stronger than the acrylic or the GRP of the boat.

[Jasetheace02 9]

2 minutes ago, Island Time said:

The is no need for the bolts/Screws, they are what eventually leaks. You could fill the holes in the frame, stick the windows in, then the frames on top for purely cosmetic reasons if you want. Modern adhesives are stronger and more flexible than the initial fixing and sealing system. Most modern boats have windows fixed without mechanical fastenings now, and the joint is usually stronger than the acrylic or the GRP of the boat.

Nice, I like the idea. As you have mentioned, one of my biggest concerns is water getting in around the screws, not the window edges! So if I use a product like MS35 its just a matter of installing (appropriate prep work obviously) and holding in place until set, maybe sometime levered of the stanchion lines?  

[Island Time 1,293]

Yep. The initial grab strength of the adhesive is pretty high, and the working time is pretty short, so it's much easier if there is two of you to position the windows. Ive done a few sets now with Quilosa MS35, and not a single leak. Its great stuff, and inexpensive. It sticks like the proverbial S.T.A.B ,  and don't use it in direct afternoon sun in summer, it goes off too fast!

A plank down the stanchions and a couple of timer braces will work fine for the required force to hold the window temporarily, it wont need much if any with the grab strength of the product. Take plenty of thinners and rags!

[Jasetheace02 9]

5 minutes ago, Island Time said:

Yep. The initial grab strength of the adhesive is pretty high, and the working time is pretty short, so it's much easier if there is two of you to position the windows. Ive done a few sets now with Quilosa MS35, and not a single leak. Its great stuff, and inexpensive. It sticks like the proverbial S.T.A.B ,  and don't use it in direct afternoon sun in summer, it goes off too fast!

A plank down the stanchions and a couple of timer braces will work fine for the required force to hold the window temporarily, it wont need much if any with the grab strength of the product. Take plenty of thinners and rags!

Great, thanks a lot.

[vic008 17]

#1 for the Quilosa

[Dtwo 157]

16 hours ago, Rehabilitated said:

Silicon for the screw holes also. No need to hold until set. Just got to remember after applying do not tighen the screws to tight just enough to squeeze all the air passages and gaps then when set tighten then. Semi rubbering and flexible and totally water tight. Not affected by uv Ray's.

It doesn't sound like you have ever used Silicon, it has absolutely no place on a boat these days.

[Black Panther 1,767]

D2 what do you use for fitting deck hardware these days?

[Stray Cat 7]

+++1 Quilosa 

[vic008 17]

BP, I like Simson products now. Had to replace the silicon around the windows. No silicon on the boat anymore.

[Jasetheace02 9]

50 minutes ago, Tamure said:

Silicon is the best sealant, Dow Corning 795 is commonly used but modified silicones (MS) are produced by a number of companies, Quilosa MS 35 is quite cheap compared to the big names and seems pretty good..  The trick is in the prep and reading the tech sheets, in particular the minimum bead thickness and surface prep for your application. 

Yes as I mentioned earlier I feel there are probably several very good products around nowadays, especially when compared to decades ago when a lot of our boats were built! Forums like this are great for me being a newbie to use the experience of others to help make good choices and reduce the risk of mistakes. All very helpful stuff. I am confident I will have a watertight boat soon!!!

[Marshy 30]

I think people are forgetting how wide the term "Silicone" goes.
Dow Corning 795 is the go to adhesive for windows, Glass, Perspex, Polycarbonate etc - it works on it all and is awesome.
Selleys All Clear - not so much... 

Each adhesive has its use cases and they are normally designed for a use case. A blanket rule saying no silicon on a boat is crazy.

[Jasetheace02 9]

Slightly off topic but still window related, peoples views on tint? Is it a must or just personal preference? My original windows were clear so I got clear acrylic but could get some stick on tint and apply before fitting the windows I guess?

[Swartch 0]

If your going to tint the Acrylic just make sure the film is compatible otherwise your going to end up in a world of hurt!! Bubbling and pealing within a very short space of time.

My thought's is tinted window's are better due to the privacy and heat reduction benefits. (I'm a window tinter by trade) and would add a film on my own boat in the future. Glass is so so much easier though.