Glued in windows- fit for purpose

[howardclark]

A few years ago I was chatting to a shipwright who was spitting feathers about a mobo window he was trying to replace which was just fitted with mastic. His described the job where it was almost impossible to remove the old broken one without damage and that that damage made fitting the replacement a right palaver. The owner was paying by the hour and it was slowly accumulating to a significant sum.
Since then I have come across several people having similar problems; there was also a storyline on the RNLI Saving lives at Sea when a similar window on the waterline when at heel ( whose fantastic idea was that?) failed and the boat nearly sank.
Today I read about a Janneau owner who can’t buy replacements and see lots of people offering advice where they have to replace windows.
I’m lucky in that I’ve got an old boat where all the windows are held in with screws.
I suspect that I would not buy a second hand boat with masticed in windows- but given the speed with which the industry is adopting this practice this will mean I will never buy a second hand boat at all!
I can see why the industry adopts this cheap solution but if a boat is to have a long life the current designs do not look fit for purpose to me.

 

[MikeBz]

...
Today I read about a Janneau owner who can’t buy replacements and see lots of people offering advice where they have to replace windows.

The Jeanneau replacements, where available, are an absurd price anyway. They can be made by various suppliers for a fraction of the cost. Removal and fitting can be very difficult, time-consuming and expensive as you say. Ask me how I know! Or don't....

 

[Tranona]

This subject was done to death here a few months ago. There are tens of thousands of glued in windows in use in yachts all round the world plus of course countless millions in cars. No signs of a rash of failures. not sure those who had to deal with the crap windows used in many British boats from the 60s through 80s with their poor sealing, corroding frames and screws that hold them together would agree with your sentiments. Doubt from what you say (and your Avatar) that you would buy a modern boat anyway.

 

[ylop]

A few years ago I was chatting to a shipwright who was spitting feathers about a mobo window he was trying to replace which was just fitted with mastic. His described the job where it was almost impossible to remove the old broken one without damage and that that damage made fitting the replacement a right palaver. The owner was paying by the hour and it was slowly accumulating to a significant sum.

Almost every job on a boat becomes a right palaver. If you pay someone to do it for you by the hour there's little motivation for them to find efficient solutions either. I have noticed over 20+ years of boat ownership that the people who do the work never seem very keen and want to explain it length how every job is a nightmare... but I wonder if they ever consider that if everyjob was quick and easy what they would do to earn money!

I’m lucky in that I’ve got an old boat where all the windows are held in with screws.

But of course old boats never have any issues with their design or maintenance do they? Sprung planks, osmosis,

the current designs do not look fit for purpose to me.

My library of sailing books long pre-dates this latest trend. They include parts on covering holes in the hull with cushions and floor boards, and wrapping sails around the outside of the hull to stem the inflow of water... Like replacing sails, engines, teak decks, standing rigging etc - its just a cost, and spontaneous failure without warning will be very unusual, that doesn't mean they are not fit for purpose.

 

[Baggywrinkle]

I remember on my dads Albin Vega, which at the time was seen as a proper seaworthy little yacht with many believing it was a viable "blue water cruiser" ... the windows were held in with gaskets similar to car windows. To get them out you just had to push a corner of the window really hard and the gasket would flex, releasing the tempered glass window - I think you had to remove a bead first but can't really remember. You could buy aluminium frame sets to make them a bit more robust - but many boats of that era employed a similar method to fix the windows. Give me a modern adhesive any day, considering the saloon windows of the Vega were closer to the water than many modern hull windows, they were just as likely to take the full brunt of a breaking wave - many stories at the time of windows popping out on otherwise capable boats (for the time).

 

[flaming]

Meh.

My glued in windows started leaking last season. The cost to have them redone (including priming with the super new sikaflex invented stuff that should stop them leaking again....) done professionally by a combination of the yard and adhesive specialists wouldn't buy me any new sails.

Annoying, but ultimately not really a big deal.

 

[geem]

I have just been watching a guy a few boats down from me in the marina with a modern boat with glued in windows. The guy is covered in sealant along with his coach roof and windows. I guess he has a few leaks. I didn't stop to chat. Suspect he won't be in the mood for banter

 

[thinwater]

Not mastic. VHB tape and either Sika 295 plus primer or Dow 795.

A heat gun takes off the old stuff. Not fun, but I took removed four 20-year old windows this spring in a morning.

I'm not really opposed to screws, but On the one boat that had those they added more work, since the holes were all buggered. Screws also ...

• Are a common source of leaks.
• Can cause window cracking if the holes are not way ovresize.
• If the leak gets into the core you really have a big job. Fairly common on older boats (rotten frame areas). Adhesive mounted windows can't do that.

I will also add that windows over about 30 inches have a MUCH higher incidence of leaks; the difference in thermal expansion between plexi and GRP is simply too much for them. At least it is a serious problem in warmer climates. When I replaced the windows on my F-24 I broke the 60" sections into 30" sections by adding a structural sash in the center.

 

[geem]

Not mastic. VHB tape and either Sika 295 plus primer or Dow 795.

A heat gun takes off the old stuff. Not fun, but I took removed four 20-year old windows this spring in a morning.

I'm not really opposed to screws, but On the one boat that had those they added more work, since the holes were all buggered. Screws also ...

• Are a common source of leaks.
• Can cause window cracking if the holes are not way ovresize.
• If the leak gets into the core you really have a big job. Fairly common on older boats (rotten frame areas). Adhesive mounted windows can't do that.

I will also add that windows over about 30 inches have a MUCH higher incidence of leaks; the difference in thermal expansion between plexi and GRP is simply too much for them. At least it is a serious problem in warmer climates. When I replaced the windows on my F-24 I broke the 60" sections into 30" sections by adding a structural sash in the center.

It's all about design. Our windows are glued and through bolted. The coach roof moulding is designed without a core material. Solid fiberglass, such that the windows are flush with the coach roof. 10 years of use and one tiny leak was fixed by simply tightening a bolt that was probably under tightened when we replaced them. Thousands of sea miles later, plenty of rough weather and temperatures from summer in the Caribbean to winter in the UK and they don't leak. You are right about thermal expansion. If you through bolt windows, there needs to be sufficient room for expansion. You can calculate the expansion rate and allow space. It's surprising how much space is needed to accommodate the potential expansion of plastic windows.
I suspect large plastic windows are impossible to make water tight long term. The thermal expansion is so great that eventually the glue bond breaks down due to movement, especially if the windows see a seasonal wide range of temperatures.

 

[thinwater]

It's all about design. Our windows are glued and through bolted. The coach roof moulding is designed without a core material. Solid fiberglass, such that the windows are flush with the coach roof. 10 years of use and one tiny leak was fixed by simply tightening a bolt that was probably under tightened when we replaced them. Thousands of sea miles later, plenty of rough weather and temperatures from summer in the Caribbean to winter in the UK and they don't leak. You are right about thermal expansion. If you through bolt windows, there needs to be sufficient room for expansion. You can calculate the expansion rate and allow space. It's surprising how much space is needed to accommodate the potential expansion of plastic windows.
I suspect large plastic windows are impossible to make water tight long term. The thermal expansion is so great that eventually the glue bond breaks down due to movement, especially if the windows see a seasonal wide range of temperatures.

^^ This. And that is the calculation I did.

Our temperature range is about -10 to 40C, not counting solar heating. Windows under 30" seem very reliable, windows over 50" not at all reliable in the long term ... and sometime even sort term. I suppose the installation temperature also matters (near the mid-point being best--I figured about 25C when solar heating is added, which made for a nice day).