Are self-tapping screws good enough to hold windows in?

[Neeves]

See my post No 18 in the other 'window' thread"

Acrylic window adhesive film thickness

The alternative to internal support of large windows are storm boards, which don't seem to engender much forum interest.

Jonathan

 

[Poignard]

Sounds like a trick question.

Properly bonded, no fasteners are required, or even advised. My last two boats had bonded frameless windows. I replace the later at ~ 20 years, and went back with bonded windows.

That's a neat piece of work, TW.

How did you go about achieving uniform thickness of sealant?

 

[Rappey]

Are self-tapping screws enough to securely fasten the windows

Yes. Try pulling a screw out with a crowbar that's screwed into decent ply.. you need a huge amount of force to rip out a screw.
Interscrews are awful things, all those extra holes for water to leak in and they are not the easiest to deal with.

 

[geem]

Removing the old windows tore out some gelcoat. One had to be broken out. I've never heard of this problem. Also, certainly stronger than the hinged hatches on the boat (weak locks and the hatch glazing is only bonded--no screws), so kind of irrelevant.

That said, nothing wrong with some screws or bolts, if just for the nerves.

There has been a couple of instances recently where bonded in windows/portlights popped out in heavy weather. One in the UK and one in New Zealand.
Friends with a Jeanneau have had their windows pop out and another we know in Portugal.
If I was going offshore I would want to be certain the windows were going to stay put. We converted out glued and screwed windows to through bolted many years ago. They don't leak and they won't pop out in any weather

 

[[193211]]

I think self tappers were a “cost effective” window fixing seen on boats from a particular period. They’ve got limitations that probably wouldn’t reveal themselves until after the warranty expired.

 

[fredrussell]

I must admit reading through this thread I was wondering if adhesive sealant alone would be enough and then Thinwater answered my question. I’m sure we’ve all tried to remove something that’s been stuck to the boat with a modern adhesive sealant. wonder if screws/fixings were used in the past because adhesives then were less effective.

 

[Neeves]

I must admit reading through this thread I was wondering if adhesive sealant alone would be enough and then Thinwater answered my question. I’m sure we’ve all tried to remove something that’s been stuck to the boat with a modern adhesive sealant. wonder if screws/fixings were used in the past because adhesives then were less effective.

The Petronas towers in KL had windows fixed with a 3M product (which is the same product used to fix our windows 25 years ago in Josepheline). The tower was opened in 1998, so similar vintage to Josepheline, and the windows must have been installed in the tower just prior. There was nothing wrong with the adhesive - it was the acrylic that failed (though it is possible the boat builder did not get the adhesive/sealant thickness right). When we came to replace the cracked windows much of the time was spent cutting the old windows out and then cleaning off the old adhesive from the underlying gelcoat. The adhesive/sealent was tenacious. We tried a cheese wire (garrotte) without success and found the best was to use a sharp filleting knife, its flexible and once you get it through the adhesive you can lever it round. For cleaning off the old adhesive once the window was removed we made acrylic chisels - simply grind a 45 degree edge and sharpen (then you do not damage the underlying gel coat). You need lots of chisels or the means handy to sharpen. Around 20mm 'working' blade and make them to comfortably grip in your hand.

The time taken to remove our windows and then re-seating the new one meant we did one window a day.

Sika do say, for some of their products, that the only known way to remove the product is by physical means.

Jonathan