How Safe are Windows in the Hull

I'm not sure ther comparing car windscreens with boat HULL windows is really very like-with-like?

Water much heavier than air (loadings), and generally the consequences of loosing a hull window much more serious than a windscreen.

There is a thread on here somewhere about the difficulties in obtaining replacement custom heavy duty glazing for boats, never mind hull windows. Specialist stuff.

I've never had any hull windows, but have experienced one factory fitted , bonded only window fail. Apparently this was due to the lack of "frits" on the window glazing, and consequent UV attack of the "glue".
 
seeSimon said:
I've never had any hull windows, but have experienced one factory fitted , bonded only window fail. Apparently this was due to the lack of "frits" on the window glazing, and consequent UV attack of the "glue".
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Have had exactly the same, one followed by the other. Got into quite the discussion with sika over it.
They've now been remedied to their exact instructions, so if it goes again.....

In general I don't think there's a big issue with hull port windows, provided that you treat them as a maintenance item on older boats.
 
Concerto said:
The car had never been involved in any accident. It the windscreen had been fixed and failed like this on a boat, it would have been a huge problem for the crew. I suppose you would just keep your fingers crossed it never happened to you whilst sailing in rough weather.
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Millions of other cars haven't been involved in accidents and their windscreens haven't developed a leak although some undoubtably have the reasons though are not known as there are unlikely to be extensive investigations.Similarly there will be some boats that suffer leaks and some even will have window failure but as of yet the numbers will be / are very small. These adhesives are incredibly strong, stronger than some parts of the boat so time will tell on how well they stand up.
 
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Fr J Hackett said:
Millions of other cars haven't been involved in accidents and their windscreens haven't developed a leak although some undoubtedly have the reasons though are not known as their are unlikely to be extensive investigations.Similarly there will be some boats that suffer leaks and some even will have window failure but as of yet the numbers will be / are very small. These adhesives are incredibly strong, stronger than some parts of the boat so time will tell on how well they stand up.
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Loosing a windscreen is not as large a problem as loosing a hull window. I suggest you read post #11.
 
Concerto said:
Loosing a windscreen is not as large a problem as loosing a hull window. I suggest you read post #11.
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Loosing a windscreen could be fatal but there again how many of the millions of cars with bonded windscreens have lost their windscreen ? How many of the few thousand boats with bonded windows have lost their windows? If they did what was the cause? You are living in the past.
 
Concerto said:
Personally I feel adding some mechanical fixings, i.e. bolts, would certainly be the best solution as the adhesive would no longer the the only way to hold the windows in place.
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Problem with mechanical fixings is that most will apply an uneven load and not flex with the body/hull.
There are countless millions of car, lorries and buses that have had bonded windows for decades now and failure of the bonding is now incredibly rare. It did happen more when it was a new thing - my guess is that boatbuilders have a similar learning curve.
 
A car is a solid unbending structure when compared to a boat. Every boat I've owned has flexed to a degree, especially when hauled out.

Convertble cars bend a fair bit too. IRRC driving a Saab 900 with an appalling amount of scuttle shake.
 
capnsensible said:
I'm not entirely sure of course, but my feeling is that designers who design boats know heaps more about designing boats than people who don't design boats.
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I think Michael_w has a point and I raised it earlier, the success or otherwise of large bonded windows will be determined if the adhesive is able to absorb the hull movement and still maintain its bond strength. I am inclined to agree with you though I think the architects will understand such things in far greater detail than us and will have done their sums so I would be inclined to trust them to have gotten it right.
 
Fr J Hackett said:
I think Michael_w has a point and I raised it earlier, the success or otherwise of large bonded windows will be determined if the adhesive is able to absorb the hull movement and still maintain its bond strength. I am inclined to agree with you though I think the architects will understand such things in far greater detail than us and will have done their sums so I would be inclined to trust them to have gotten it right.
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The moulded recess for the hull window should stiffen the area the window is fixed to but evidence of bonding failure shows this must still not be adequately stiffened or incorrectly prepared.

Talking with the crane driver at a marina in the Solent a couple of years ago was interesting. With his travel hoist he had to be very careful where he placed the slings on modern boats and to check where the cradle chocks were positioned as they must be on a bulkhead. If not the hull could flex in strong winds and the boat could slip in the cradle. This is to show how flexible modern hulls can be and cannot be considered to be a rigid structure. Modern design using an inner matrix moulding has allowed a rigid core of the main stress loadings. They may be designed to take the loadings for the rigging and keel, but other areas are not structural. It always come back to the cost to manufacture. Hulls are increasing in volume, yet the hull weight excluding the keel remains the same. Placing openings in the hull for windows is a fashion trend that is suitable for boats that are used only in fair weather, but in my opinion they are an accident designed to happen at sometime in the lifetime of the boat. I have no objection to small hull windows with a metal frame that is mechanically fixed to the hull, but multiple panoramic windows is designers gone mad.
 
Concerto said:
The moulded recess for the hull window should stiffen the area the window is fixed to but evidence of bonding failure shows this must still not be adequately stiffened or incorrectly prepared.

Talking with the crane driver at a marina in the Solent a couple of years ago was interesting. With his travel hoist he had to be very careful where he placed the slings on modern boats and to check where the cradle chocks were positioned as they must be on a bulkhead. If not the hull could flex in strong winds and the boat could slip in the cradle. This is to show how flexible modern hulls can be and cannot be considered to be a rigid structure. Modern design using an inner matrix moulding has allowed a rigid core of the main stress loadings. They may be designed to take the loadings for the rigging and keel, but other areas are not structural. It always come back to the cost to manufacture. Hulls are increasing in volume, yet the hull weight excluding the keel remains the same. Placing openings in the hull for windows is a fashion trend that is suitable for boats that are used only in fair weather, but in my opinion they are an accident designed to happen at sometime in the lifetime of the boat. I have no objection to small hull windows with a metal frame that is mechanically fixed to the hull, but multiple panoramic windows is designers gone mad.
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Both my Vancouvers (274 and 34) required the lifting slings to be arranged to coincide with bulkheads if you didn't it definitely caused the hull to deform as witnessed when it was done once and the tabbing / bonding of the heads module and a hanging locker on the 34 failed requiring rebonding, it's not a problem that has only arisen in modern boats.
There are plenty of boats like the modern Oysters that have circumnavigated and spent a long time at sea without their bonded windows falling out and the boat sinking.
When the evidence of failure starts to point to a design or engineering problem that will be the time to worry.
 
It’s not a design problem, its a design life problem. The failures that have been reported have been on boats old enough that the adhesive should have been replaced. That’s no more a design issue than an old sail blowing out. The traditional windows on my 25 year old boat are starting to leak a bit for the same reason, nothing lasts forever.
 
awol said:
I wish you lot would stop wittering on about windows and answer the important question from Post #1.
How does a yacht without a sail number take part in a race?
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Easy. Get to the start line on time and sail the course. Most yacht races require a class flag on the backstay and not to fly an ensign to show you are racing. Just notify the Officer of the Day that you do not have any sail numbers and to look out for you. Providing a photo would also be advisable.

If they are not happy to do this then you might be required to have a number board fixed on both sides of the boat or numbers applied to the topsides. The final alternative would be to get a sail maker to supply some self adhesive numbers and stick them on your mainsail. Many boats have numbers to just indicate when the boat was completed in the production run, so the exact numbers do not matter as it is unlikely another race boat will have the same numbers.
 
I don't think I'd want a boat that required periodic refixing of hull windows, even if the period was twenty years. It sounds like a major pain in the arse, with the prospect of terrible consequences if you don't do the job right. When your sails get old, the boat doesn't rapidly fill with water.
I know there are thousands of boats like this out there, happily sailing around, but many of their owners also put up with other expensive maintenance requirements that I wouldn't want to have to deal with.
 
MisterBaxter said:
I don't think I'd want a boat that required periodic refixing of hull windows, even if the period was twenty years. It sounds like a major pain in the arse, with the prospect of terrible consequences if you don't do the job right. When your sails get old, the boat doesn't rapidly fill with water.
I know there are thousands of boats like this out there, happily sailing around, but many of their owners also put up with other expensive maintenance requirements that I wouldn't want to have to deal with.
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Its certainly no worse that saildrive maintenance every 6 years or so, and thats an enormous hole on the bottom of the hull.
 
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