glass thickness for decksaloon windows

[kingsebi]

I'm shopping around decksaloon windows and got different quotes for 4, 6 and 8 mm toughened glass. What do you think? I ultimately plan to cross oceans with the boat. Side windows are 1000 x 500 mm, front windows 500 x 500 mm. Obviously prices go up with thickness. Another question I'm asking myself is, if I get double glazed units, what would happen if a breaking wave smashes the outer pane into tiny pebbles - would the inner pane break aswell? Maybe best to prepare stormboards before a passage anyway?

 

[John the kiwi]

You may find this interesting and sobering reading.
Maritime NZ Report: Storm covers may have prevented the loss of sailing vessel, Essence - Maritime NZ
I recommend you down load the report from the website.

 

[NormanS]

The double glazed windows on my deck saloon are 6mm. The PO, who did some ocean passages, and acting on advice, got storm windows for the side windows. Strangely, the perceived wisdom was that they were not required for the front ones.

 

[jwilson]

A friend bought a very expensive new deck saloon cruising catamaran and on it's first proper open sea passage (about 600 miles, not extreme weather) had the big front windows smashed by a bit of green water. A lot of interior water damage ensued. I know the conditions were not extreme as we were both in the Cruiser division of a 600 mile race and we ended up finished ahead in a smaller monohull. I was very surprised to arrive at the finish and find he was not there yet.

 

[Stemar]

Another question I'm asking myself is, if I get double glazed units, what would happen if a breaking wave smashes the outer pane into tiny pebbles - would the inner pane break aswell?

Without having done any research, I think I would want laminated glass. It breaks easier, but the laminate holds the bits together.

As for thickness, I'd be looking for as thick as will fit in the frames. It may be more expensive, and I hope you'll never know if you wasted your money, but I'd rather be a bit poorer than be out there worrying whether the windows will hold.

 

[Minerva]

I've been loosely thinking about this too - before boat prices went crazy, I was looking to upgrade current boat to a deck saloon...

The conclusion I came to over a dram, was regular laminated glass for most deck saloon windows, nothing particularly overkill (but able to withstand being submerged with the boat turtle - should be easy enough to calculate the water pressure involved). But with 15-20mm clear polycarbonate storm boards spaced 10mm or so off the outside of the glass. Should give adequate protetecion when offshore, and the spacing allow a little flex if hit by green water.

In normal, coastal use, they can be tucked away in a nice bag under a bunk, then when going offshore could be fitted for a bit of insurance. Fitting would be by recessed nuts bonded in 10mm spacers laminated onto the outside of the cabin top.

I think that would cover wave protection OK.

 

[jwilson]

This thread got me to dig out from the bottom of a drawer a small souvenir - a chunk of what was then a newish 10mm acrylic port from a UFO34 - this was about 40+ years ago part of a quite small side coachroof window. What hit it - water.....

Minerva said "....able to withstand being submerged with the boat turtle". Unfortunately real-life inversions are not gentle - think of the entire boat being picked up and slammed down part or fully inverted. Hence Minerva's correct solution of storm boards if you really want big windows deep sea.

I'd quite like a deck saloon yacht now, but it would never be where I was on that inverted UFO - far north and early in the year.

 

[[2574]]

I replaced the deck saloon windows in our Nauticat, had the new windows made by a firm in Denmark who had all the Nauticat design drawings. I remember wrestling with the specification but was assured by the Danish firm that they were built to an international quality standard - ISO standard IIRC. I was surprised that there was a standard so specific to yacht windows but I checked it out and indeed there was a detailed standard on the subject. I think the Nauticat windows were 8mm forward and 6mm side but that needs checking.

 

[Rappey]

what would happen if a breaking wave smashes the outer pane into tiny pebbles - would the inner pane break aswell?

No ! Not until the same force acts on the inner pane. Forget laminated as toughened is 5 times stronger than non treated.
1000x500 is a large size and I would consider storm boards as increasing the thickness of the glass would add much more weight and cost.

 

[John the kiwi]

This thread got me to dig out from the bottom of a drawer a small souvenir - a chunk of what was then a newish 10mm acrylic port from a UFO34 - this was about 40+ years ago part of a quite small side coachroof window. What hit it - water.....

Minerva said "....able to withstand being submerged with the boat turtle". Unfortunately real-life inversions are not gentle - think of the entire boat being picked up and slammed down part or fully inverted. Hence Minerva's correct solution of storm boards if you really want big windows deep sea.

I'd quite like a deck saloon yacht now, but it would never be where I was on that inverted UFO - far north and early in the year.

a quote from the report i referenced earlier about the loss of the Bavaria47. The windows blew outward - not inward.

The crew stated that the impact of the vessel falling into the trough caused the windows to blow out. This may also have caused the forward hatch to open. The impact of landing in the trough is likely to have caused the hull, cabin and deck to flex due to hydraulic forces. This is also likely to have caused pressure within the cabin which, combined with the flexing, may have caused the windows to blow out. It is noted that prior to the final knockdown, a crewman observed the cabin flexing due to wave pressure. 12 22 July 2021 MARITIME NEW ZEALAND The loss of the sailing vessel, EssenceThere is an increasing trend to have larger windows, in particular among production vessels that are touted as being suitable for ocean voyages. The larger the area of window, the greater the risk of failure, particularly for many production vessels that are subject to flexing in extreme conditions. There is a commonly held view that windows will always break inwards due to external wave pressure and this can often be the case, however, many relatively modern production vessels, such as Essence, are constructed from materials that are more susceptible to flexing under pressure. This, when combined with the larger windows that are commonly found in modern sailing vessels, makes the rebated substrate area around the windows more susceptible to failure.

 

[burgundyben]

My wheelhouse front windows are 10mm toughened glass. About 1mtr wide and 0.7mtr tall.

Sides are 6mm.

 

[Rappey]

A 72ft vsv I know has 50mm glass screen.

 

[kingsebi]

You may find this interesting and sobering reading.
Maritime NZ Report: Storm covers may have prevented the loss of sailing vessel, Essence - Maritime NZ
I recommend you down load the report from the website.

Sobering read indeed.

The double glazed windows on my deck saloon are 6mm. The PO, who did some ocean passages, and acting on advice, got storm windows for the side windows. Strangely, the perceived wisdom was that they were not required for the front ones.

Thanks for the information. I would have thought storm windows for the front aswell. Maybe because the mast would deflect the water?

Without having done any research, I think I would want laminated glass. It breaks easier, but the laminate holds the bits together.

As for thickness, I'd be looking for as thick as will fit in the frames. It may be more expensive, and I hope you'll never know if you wasted your money, but I'd rather be a bit poorer than be out there worrying whether the windows will hold.

The problem with laminated is that it doesn't offer the same thermal insulation. I get your argument. That's what I thought aswell. Better spend more and have peace of mind.

I've been loosely thinking about this too - before boat prices went crazy, I was looking to upgrade current boat to a deck saloon...

The conclusion I came to over a dram, was regular laminated glass for most deck saloon windows, nothing particularly overkill (but able to withstand being submerged with the boat turtle - should be easy enough to calculate the water pressure involved). But with 15-20mm clear polycarbonate storm boards spaced 10mm or so off the outside of the glass. Should give adequate protetecion when offshore, and the spacing allow a little flex if hit by green water.

In normal, coastal use, they can be tucked away in a nice bag under a bunk, then when going offshore could be fitted for a bit of insurance. Fitting would be by recessed nuts bonded in 10mm spacers laminated onto the outside of the cabin top.

I think that would cover wave protection OK.

I guess I will go for stormboards. Seems like the sensible solution.

This thread got me to dig out from the bottom of a drawer a small souvenir - a chunk of what was then a newish 10mm acrylic port from a UFO34 - this was about 40+ years ago part of a quite small side coachroof window. What hit it - water.....

Minerva said "....able to withstand being submerged with the boat turtle". Unfortunately real-life inversions are not gentle - think of the entire boat being picked up and slammed down part or fully inverted. Hence Minerva's correct solution of storm boards if you really want big windows deep sea.

I'd quite like a deck saloon yacht now, but it would never be where I was on that inverted UFO - far north and early in the year.

Wow, scary...

I replaced the deck saloon windows in our Nauticat, had the new windows made by a firm in Denmark who had all the Nauticat design drawings. I remember wrestling with the specification but was assured by the Danish firm that they were built to an international quality standard - ISO standard IIRC. I was surprised that there was a standard so specific to yacht windows but I checked it out and indeed there was a detailed standard on the subject. I think the Nauticat windows were 8mm forward and 6mm side but that needs checking.

Thanks for the information. I thought 6-8 mm would be sensible. 4 mm seems to be awfully thin.

No ! Not until the same force acts on the inner pane. Forget laminated as toughened is 5 times stronger than non treated.
1000x500 is a large size and I would consider storm boards as increasing the thickness of the glass would add much more weight and cost.

That's what I thought. The outer pane would break but the small pieces couldn't carry enough force to break the inner pane. But well, how to be sure? Better to have stormboards for passages.

My wheelhouse front windows are 10mm toughened glass. About 1mtr wide and 0.7mtr tall.

Sides are 6mm.

Thanks for the information.

A 72ft vsv I know has 50mm glass screen.

Don't think my boat is a Very Slender Vessel. Haha.

 

[vyv_cox]

A little info. The side windows on VW vans, in the sliding doors, are toughened 4 mm glass. These have a very hard life but I know of no breakages. When I replaced the wheelhouse windows on a small inshore motorsailer I used 4 mm toughened glass.

 

[Neeves]

The double glazed windows on my deck saloon are 6mm. The PO, who did some ocean passages, and acting on advice, got storm windows for the side windows. Strangely, the perceived wisdom was that they were not required for the front ones.

I wondered about this...

When the winds are 55 knots and increasing and the developed seas would break over the cabin roof - .......who punches into seas to windward - don't we all aim for off the wind?, or across the seas?

How many of you have tried to make headway in 55 knots head wind, with the accompanying seas in open water - in a yacht? You don't, or cannot (make headway) you reach off. Lee shore? - you did not check the forecast beforehand.

If conditions get worse - that's why you have a para anchor or drogue.

Jonathan

 

[jwilson]

I have used 40 hp diesel at near full throttle on a 34 ft yacht to basically stay static into very heavy weather and breaking seas - much as trawlers "dodge" in similar conditions. It's a valid technique, especially after we had been inverted when running under bare poles. It worked well till the engine died.

 

[Rappey]

I have beaten 4 and 6mm toughened on its face with a 3ft crowbar in a skip and often it bounces off.
Double the thickness of the glass and it roughly quadruples it's impact resistance.
The spinnaker tower walk on glass is 3 layers giving 60mm total and apparently has a max loading of just over 1800kg.
6mm toughened at 1000x500mm as a table top has a loading of around 45kg. But that's with 4 support posts rather than supported around its whole perimeter.

 

[kingsebi]

A little info. The side windows on VW vans, in the sliding doors, are toughened 4 mm glass. These have a very hard life but I know of no breakages. When I replaced the wheelhouse windows on a small inshore motorsailer I used 4 mm toughened glass.

Thanks, interesting.

I have beaten 4 and 6mm toughened on its face with a 3ft crowbar in a skip and often it bounces off.
Double the thickness of the glass and it roughly quadruples it's impact resistance.
The spinnaker tower walk on glass is 3 layers giving 60mm total and apparently has a max loading of just over 1800kg.
6mm toughened at 1000x500mm as a table top has a loading of around 45kg. But that's with 4 support posts rather than supported around its whole perimeter.

I think I will go for 6 or 8 mm.

 

[Supertramp]

I wondered about this...

When the winds are 55 knots and increasing and the developed seas would break over the cabin roof - .......who punches into seas to windward - don't we all aim for off the wind?, or across the seas?

How many of you have tried to make headway in 55 knots head wind, with the accompanying seas in open water - in a yacht? You don't, or cannot (make headway) you reach off. Lee shore? - you did not check the forecast beforehand.

If conditions get worse - that's why you have a para anchor or drogue.

Jonathan

I think the OP is on the right track in replacing with the thickest, toughest glass he reasonably can.

Once you get into 55knt+ situations with associated seas you will be into all kinds of risks, with windows breaking just one of many. I think the logic of protecting side windows is the risk of being hit sideways by a breaker, with the risk to the leeward side just as much as the windward. I would be starting to worry about hatches and doorways as well.

If I was exposing myself to a likelihood of extreme seas and wind (Southern or Northern oceans) then I would choose a boat free from some of the more obvious weaknesses. Otherwise I would plan routes to avoid extreme weather and have a run for shelter option.

I remember a comment from the Chandlers' book before they became hostages to the effect that they had never sailed in more than a F6 in 7 years of circumnavigating. I think that is a triumph of seamanship and judgement. No doubt they had window covers as well......

 

[kingsebi]

I think the OP is on the right track in replacing with the thickest, toughest glass he reasonably can.

Once you get into 55knt+ situations with associated seas you will be into all kinds of risks, with windows breaking just one of many. I think the logic of protecting side windows is the risk of being hit sideways by a breaker, with the risk to the leeward side just as much as the windward. I would be starting to worry about hatches and doorways as well.

If I was exposing myself to a likelihood of extreme seas and wind (Southern or Northern oceans) then I would choose a boat free from some of the more obvious weaknesses. Otherwise I would plan routes to avoid extreme weather and have a run for shelter option.

I remember a comment from the Chandlers' book before they became hostages to the effect that they had never sailed in more than a F6 in 7 years of circumnavigating. I think that is a triumph of seamanship and judgement. No doubt they had window covers as well......

Like you say, my plan is to avoid extreme weather in the first place, but one never knows...