Broom query - glued frameless windows

[oceanfroggie]

Quick user experience query for broom owners about the glued frameless windows introduced to their new models about 5 years ago. Previous to that they had metal window frames, either aluminium or stainless steel. The new ones look nice, just wondering how well they had worked out? Any broomers had these for a few seasons? Thanks

 

[rafiki_]

Not a Broomer personally, sorry, but isn't this method becoming the norm for boats? Bonded windows have been the norm in cars for 20 odd years, so the technology is well knowned. Of course the grp frames in boats are probably not quite as stable as a car monocoque, but I'm not aware of any generic probs with boats. You might call Robin Thatcher at Trend Marine. They supply the windows for the majority of UK built boats, and are just up the road from Brundall.

Good luck.

 

[jfm]

+1. not specific to Broom, but I've had bonded windows on last several boats and they are way better than framed windows. I cannot think of one downside to bonded glass. The boatbuilder needs to use a quality glue provider like sika - there have been cheaper products used regrettably by builders who tried to save cost for a while that caused problems, which Trend know all about but probably wont reveal As rafiki says this is a very well established technology now with easily over a billion car windows installed using bonded glass

 

[kcrane]

Which reminds me that the windows on the owners cabin on the V52 seemed to have new bonded windows, one large sheet of glass (quite close to the waterline) with an inset porthole. I think they originally had mullions (if that's the right word) splitting the windows into three sections.

Is it the bonding that is improving and allowing the large sheets of glass close to the waterline, or is it the glass itself which is stronger?

I do remember being told, in the olden days when I was having a sunroof fitted aftermarket, that fitting the glass panel actually strengthened the roof, not weakened it. I suspect that was to do with the rigid frame to hold the panel.

 

[oceanfroggie]

Thanks guys. I know the auto industry has used bonded windows successfully for years using precision mass production line technology. I was wondering how well bonded windows on leisure mobos would stand up over time. Production volumns in marine sector are tiny compared to auto and I assume assembly is manual. Compared to auto windows, mobo windows are a lot larger and attached to grp superstuctures that must flex a little over years of use at sea, especially if pounding a strong head on sea. They look a lot nicer, but I was wondering about how bonding and seal stood up over the years (ie effect of vibration, sea, expansion/contraction, etc, on glue joints). Had most uk mobo builders moved to bonded windows about the same time?

 

[DAKA]

IMHO you are right to be concerned.
Bayliner were one of the first to use bonded windows that I noticed back in the late 80s early 90's

Every time i went out in a head sea exactly what you fear happened, the windows came adrift and leaked.

I ended up oversize drilling the glass (plastic but bent so real care required), few screws to add to the glue and job sorted.

I accept that is a long time ago and technology should have improved.

 

[jfm]

Which reminds me that the windows on the owners cabin on the V52 seemed to have new bonded windows, one large sheet of glass (quite close to the waterline) with an inset porthole. I think they originally had mullions (if that's the right word) splitting the windows into three sections.

Is it the bonding that is improving and allowing the large sheets of glass close to the waterline, or is it the glass itself which is stronger?

I do remember being told, in the olden days when I was having a sunroof fitted aftermarket, that fitting the glass panel actually strengthened the roof, not weakened it. I suspect that was to do with the rigid frame to hold the panel.

It's all the aspects that have got better: the glass, the glue and the fritting. In a car the glass is part of the structure and if you removed the glass the car would be a floppy tin thing that wouldn't pass any crash tests or anything. Glass is a wonderful material these days as you know. you can make bridges from it

I wouldn't agree in the context of those old aftermarket sunroofs (I used to fit them to mates cars at school), becuase of the poor interface twixt sunroof frame and car sheet metal, but it help garages (/me) sell 'em I suppose. But with glue that interface problem is cured

Classification societies and boat builders have had interesting discussions on this around 10 years ago. Ferretti got RINA to accept that the glass panels down to waterline are not windows; rather they are parts of the hull that happen to be transparent. This paved way for Absolute and others to follow suit and take glass down to waterline. And good on 'em - they are technically correct

You still come across luddite builders who wont accept bonded glass in a hull and insist on clamped frames. SanLorenzo, for example, plus many of the Trawler builders. Shame, co it spoils their otherwise magnificant boats.

As well as the glass the two other big aspects are the glues and the fritting (the black stuff with the dots). The fritting is generally ceramic onto glass, and hides the glue plus protects it from UV, as well as facilitating "different sized windows inside and out", as is very common on cars. The glue bonds the fritting to the car/boat, so the fritting has to be well bonded to the glass else it is the weak link, and the auto industry have got that fixed by making the fritting (printed) ceramic so it sticks to the glass.

Clever stuff and generally a nice bit of engineering/chemistry all round. All the luddite boat builders who do not believe glue is as good as nuts/bolts/rivets had better not fly on any Airbuses

Ref your mention of mullions, actually a lot of the big glass sheets you see still have mullions on the inside, hidden from view by fritting

 

[jfm]

I know the auto industry has used bonded windows successfully for years using precision mass production line technology.

No, all auto technology has to be transportable to the mom n pop repair shops else it isn't acceptable. Cars that can't be repaired are uninsurable, which would mean no-one would buy them. There are establised procedures and wide enough tolerances that small-production shops can bond glass to a perfectly good standard.

Daka's reference is to old technology not involving glass. Just not relevant. There is virtually zero failure in glass bonded to GRP in boats. When you see them being built there is careful work done to make the GRP panels close to the glass very stiff: you cant bond a floppy thing to a stiff piece of glass and expect the glue to hold in pounding seas. Hence all the muillions you see on GRP boat windows (I don't think there is any large GRP boat window that isn't mullioned, is there?). It's great technology, way better than frames

 

[wakeup]

I learnt a new word today, "Fritting"

 

[oldgit]

Many early cars including Lotus cars of the 1970s used a system where a adhesive "seal " was placed around the car window frame and the window glass held in position by hand/tape/gravity.
A electric current was passed round the entire seal by way of a wire buried in the goo.
The heat from the wire softened the seal which then bonded glass and frame together as it cooled and shrank it gave a very strong bond.

 

[kcrane]

I learnt a new word today, "Fritting"

Me too, I thought the black edging was to 'shape' the window to the observer's eye to fit the designer's concept and secondly to reduce glare/heat build up. Hadn't dawned on me it was structural or ceramic.

I remember I had a pig of a job getting a BMW internal mirror (a chunky heavy thing) to re-attach when it failed. I suspect the windscreen had been changed and they'd done a poor job of attaching the mirror. I tried several solutions until I found the right glue, when it stuck fast no problem.

jfm - I don't know how big you are thinking a 'large GRP boat window' would be, but IIRC the reason the V52 window stuck in my mind was it was the size of the old 2 mullion/3 pane jobbie, but was a single piece with no support other than the frame.

 

[rafiki_]

The heated glue for bonded windows died in the early '80's. Any replacement car windows are fixed on the side of the road with a sika bonding, sets ok within an hour.

Marine windows are growing and the limit in size has more to do with the suppliers tooling capacity. Trend don't have the tools to mould the Sealine f48 windows, but are supplying the very similar ones, albeit slightly smaller f42 windows.

 

[jfm]

Me too, I thought the black edging was to 'shape' the window to the observer's eye to fit the designer's concept and secondly to reduce glare/heat build up. Hadn't dawned on me it was structural or ceramic.

Structural and UV. With polyurethane glues and stuff UV degradation is a big deal. The ceramic fritting is very opaque to UV

jfm - I don't know how big you are thinking a 'large GRP boat window' would be, but IIRC the reason the V52 window stuck in my mind was it was the size of the old 2 mullion/3 pane jobbie, but was a single piece with no support other than the frame.

Not sure what size i had in mind either . It's all to do with stiffness. If you glue a floppy sheet to a stiff sheet you can split the glue joint by peeling the floppy one off the stiff one. There is only a single "front" of molecules that have to be parted as the peel effect occurs. Conversely if you glue two very stiff things together you cannot peel, and to bust the glue joint you have to sever all the molecules in one go not just line of molecules along the the "peel front"

Imagine sticking two 32mm sheets of marine ply together with strong glue. Then imagine gluing a 5mm sheet to a 32mm sheet - you could peel it off

Glass is stiff - you can't make it floppy. So to avoid glue peel the GRP around the window therefore has to be made stiff as well. Hence the design of the GRP part and the mullions etc. You can fit a huge window without mullions if the GRP around the window aperture is stiffened, and that is what Princess must have done.

Indeed, now that we have lots of fab big glazing in mobo hulls (and rag+stick -see the Oysters) the Next Big Thing is probably getting rid of the mullions...

Rafiki's very valid point about glass supplier's facilities is true but is not currently the bottleneck in hull glazing. The Sealine F46 windscreen is huge and in a league of its own in terms of making the thing. Remember manufacturers like Trend and Yachtglass have all been doing bonded fritted patio door glass in mobos for years, and they can easily handle that size, and that is way bigger than current hull glazing. In other words all the mainstream suppliers can in principle already supply a 2m x 1.5m curved and fritted master cabin hull window if you want one [Memo when ordering these: specify the black privacy glass in Med marinas for shaagging purposes]

 

[oceanfroggie]

All the luddite boat builders who do not believe glue is as good as nuts/bolts/rivets had better not fly on any Airbus

But those aircraft are built to aerospace standards with FAA certification and testing to the nth degree! But I get your drift.

 

[jfm]

...built...

Glued together

 

[MapisM]

You still come across luddite builders who wont accept bonded glass in a hull and insist on clamped frames. SanLorenzo, for example, plus many of the Trawler builders. Shame, co it spoils their otherwise magnificant boats.

LOL, I guess that also PJ or RH account for luddite builders, just as a couple of examples...

Besides, proper trawlers are made of steel, and you don't want to loose the collision resistance properties of steel (through flexing) by putting a sheet of non-flexing glass anywhere near the w/l. I've yet to see any ice classed boat with hull windows, in fact...

All that said, I must admit that the real reason why I don't like hull windows is that they are freaking useless. All you need in cabins are portholes to ventilate them in hot weather, and windows do exactly the opposite: you can't open them, they make the cabin even hotter, and they are a pita to keep clean. Not to mention that they increase production costs, which in turn means that you pay more for the pleasure to look at a landscape which you could enjoy much better from above, anyway.

PS: now, where's my coat...?

 

[moonraker 36]

its a polyurethane adhesive.
the automotive side dont really use silkaflex(although it is a good system).
the market leader is company called DOW.
the most important bit when it comes to bonding glass is that the apreture and glass obscuration band are cleaned and primed,the primer is avery important part it gives the bond a really good base to stick to.
the black boarder on the glass hides the bond line and any unsightly edges from vue,
but its main roll its to stop uv light degrading the bonding.
one of the heaviest glass i have fitted would be around 110kg(anti bandit screens on security vans,coaches usually top out around 90kg).

 

[rafiki_]

[Memo when ordering these: specify the black privacy glass in Med marinas for shaagging purposes]

Is this a box you forgot to tick on Match 1

 

[moonraker 36]

Me too, I thought the black edging was to 'shape' the window to the observer's eye to fit the designer's concept and secondly to reduce glare/heat build up. Hadn't dawned on me it was structural or ceramic.

I remember I had a pig of a job getting a BMW internal mirror (a chunky heavy thing) to re-attach when it failed. I suspect the windscreen had been changed and they'd done a poor job of attaching the mirror. I tried several solutions until I found the right glue, when it stuck fast no problem.

jfm - I don't know how big you are thinking a 'large GRP boat window' would be, but IIRC the reason the V52 window stuck in my mind was it was the size of the old 2 mullion/3 pane jobbie, but was a single piece with no support other than the frame.

not a fitting fault(manufactures fault).
the bmw mirrors twist off a metal boss that comes on the glass allready.
if the boss did come off we reattached with a two part glue from loctite...they didnt fall after that.!

 

[moonraker 36]

Many early cars including Lotus cars of the 1970s used a system where a adhesive "seal " was placed around the car window frame and the window glass held in position by hand/tape/gravity.
A electric current was passed round the entire seal by way of a wire buried in the goo.
The heat from the wire softened the seal which then bonded glass and frame together as it cooled and shrank it gave a very strong bond.

not a good system now adays.
some people used the wire to heat the cold bond up to remove a damged screen..they damaged the car as well! gave of fumes as well so the system didnt last long before it got dropped.