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Old 14-09-2021, 12:44   #16
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Re: How do I make window frames for my CAL 31?

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Originally Posted by Franziska View Post
Your right about Lexan which is polycarbonate.
Tough like hell, but scratches more easily than Plexi.
The toughness of Lexan is great for any front facing windows which might get green water on it.
Polycarbonate has better impact strength but is weaker in every other way.
For my windows I use cast acrylic, Plexiglas GS, since I don't expect anyone to be shooting at me.
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Old 14-09-2021, 12:57   #17
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Re: How do I make window frames for my CAL 31?

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Originally Posted by Anders View Post
Polycarbonate has better impact strength but is weaker in every other way.
For my windows I use cast acrylic, Plexiglas GS, since I don't expect anyone to be shooting at me.
If you have windows which do not risk the watertight integrity when stuffed in by a big wave that's probably fine.

Any front window I would not want to take risks, therefore polycarbonate.
I agree the better scratch resistance and clarity of plexi is nice, but not at the price of safety.

But, that is my personal point of view..
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Old 14-09-2021, 13:23   #18
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Re: How do I make window frames for my CAL 31?

We are looking to get rid of the aluminium frames as they suffer condensation in the winter which is really annoying.

I see people using VBA tape to hold acrylic in now. You have to get the alignment right because its a one shot and no way of adjusting later.

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Old 14-09-2021, 13:23   #19
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Re: How do I make window frames for my CAL 31?

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Originally Posted by Franziska View Post
If you have windows which do not risk the watertight integrity when stuffed in by a big wave that's probably fine.

Any front window I would not want to take risks, therefore polycarbonate.
I agree the better scratch resistance and clarity of plexi is nice, but not at the price of safety.

But, that is my personal point of view..
I suggest you research polycarbonate vs cast acrylic before changing windows next time. Polycarbonate is only better for impact strength. Cast acrylic is stronger if a wave breaks over your window.
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Old 14-09-2021, 13:45   #20
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Re: How do I make window frames for my CAL 31?

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Originally Posted by Anders View Post
I suggest you research polycarbonate vs cast acrylic before changing windows next time. Polycarbonate is only better for impact strength. Cast acrylic is stronger if a wave breaks over your window.
Poly might crack at worst, but it will not open a huge hole...
The Plexiglas can burst much more easily into many pieces..
Especially if it is thoroughly held around its complete perimeter.
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Old 14-09-2021, 13:54   #21
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Re: How do I make window frames for my CAL 31?

Yes polycarbonate will open a huge hole long before the same thickness of cast acrylic would for the same breaking wave. Polycarbonate is only stronger for impact resistance such as a bullet hitting your windows. I suggest you research the strength and weakness before changing windows again.
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Old 14-09-2021, 22:22   #22
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Re: How do I make window frames for my CAL 31?

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Originally Posted by Anders View Post
Yes polycarbonate will open a huge hole long before the same thickness of cast acrylic would for the same breaking wave. Polycarbonate is only stronger for impact resistance such as a bullet hitting your windows. I suggest you research the strength and weakness before changing windows again.
So, than explain to me why, for example, one of the most strict classification societies Det Norske Veritas (DNV) specifically prefers polycarbonate as window material for lifeboats:

".. 2.2 Windows in rigid enclosures 2.2.1 Windows in rigid enclosures shall be at least 500 mm above the waterline at full load of the boat.
2.2.2 Window panes Panes shall be preferably made of polycarbonate (“PC”) or polymethylmethacrylate (“PMMA) mate-rial which shall be UV-stabilized. Scratch resistance is required if wipers are provided, otherwise it is recommended. Heat toughened safety glass may only be approved in connection with testing of strength and tightness emulating service conditions.."

Source:
https://www.google.com/url?sa=t&sour...VwJS3lLiUNtZb1

The RNLI uses it apparently as well as windscreen material:
https://www.eagleboatwindows.co.uk/lifeboats

If authorities like these actually ask for polycarbonate, I am pretty convinced that they have done their research before.

For offshore use on exposed areas it is preferable in my eyes.
Im glad we have 10mm Polycarbonate :-)
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Old 14-09-2021, 23:51   #23
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Re: How do I make window frames for my CAL 31?

Every hatch made (with the exception of one model of Bomar) uses acrylic.

The same goes for virtually all non-glass portlights.

The following is from Tony at Select Plastics/Hatchmasters:



01/19/20
Acrylic vs. Polycarbonate
I spend inordinate amounts of time discussing the pros and cons of acrylic and polycarbonate. In so much as I would like to bring some clarity to this issue. Please consider the following:

All major hatch, portlight, and window manufacturers use Acrylic in offshore / bluewater marine products.
Acrylic is more scratch resistant than standard (9034) polycarbonate.
Acrylic is significantly more durable when exposed to Ultra Violet radiation (sunlight).
Acrylic is less expensive than Polycarbonate.
Don’t misunderstand my preference for acrylic. I buy, use and sell a significant amount of both products and each has its application. In my humble opinion Acrylic is more durable, versatile and cost effective in the hands of a skilled craftsman than polycarbonate.

Additional considerations may include polycarbonate with UV and scratch resistant coatings. While these products are heavily promoted by several manufacturers and carry 5, 10 even 15 year warranties the following information has been reported in “real life” applications:

Polycarbonate is impact resistant. When it’s new it is almost impossible to break.
Small quantities (less than a 4 by 8) in gauges over 1/8th inch are difficult to find in the UV- scratch resistant grades.
Colors are limited. Only two standards (gray and bronze). Try and find anything thicker than 1/4 in UV/ scratch resistant!
Polycarbonate foreshortens when subject to static or dynamic loads. What this means is if you replace your hatch lens with polycarb, seal it and then step on it the ductile material will deflect (bow) in the center. One of two things may happen. 1st you will surely break the watertight seal, 2nd you may end up with a leg in your salon.
As for the warranty: The original owner is warranted against failure subject to the material being submitted to the distributor for evaluation with the original invoice subject to actual replacement cost at the time of purchase. I guess this means they sell you a new square of material and apply the old payment to the new cost. How about the labor to fabricate the part, install it and sealant? Why take the chance?
Polycarbonate is a great material; The US Air force uses it for fighter canopies! I sell Polycarb to the USCG and US Navy. Remember they don’t mind using it because we are paying to replace it every three years.
Both Acrylic and Polycarbonate have specific uses and installation requirements.

Cast Acrylic (of a specific thickness) is in accordance with CE and ABYC guidelines, and installed on virtually all of the big blue- water sail boats produced on both sides of the pond. Polycarbonate is commonly used as a replacement due to its ease of fabrication and incredible initial strength. The USCG and USN require Polycarbonate on their vessels but they also have a preventative maintenance cycle of 36 to 42 months for change out. My Tax dollars at work…

Due to its ductility Polycarbonate it is more challenging to install. I have seen Sika Flex 295UV with primer and Dow 795 both mentioned. I use and recommend both. Dont go over 4 ft continuous length with a fixed portlight. Remember the coefficient of thermal expansion for Acrylic and Polycarbonate is in the neighborhood of .000039 per inch per degree F. That means an 8ft plastic port will expand and contract up to 1/2 of an inch from the coldest day in Feb to the hottest day in summer. WOW!! Compartmentalize the job. It will be easier to install and less prone to leaks.

Never ever bolt a plastic portlight in place. Screws are fine to hold a lens till the adhesive cures. Take them out asap and fill the holes with the aforementioned products. Both of these products are rated at 700 + percent elongation before tear. Strong flexible and UV resistant.

Been to a boat show lately? Seen any screws? Glass is good so long as your boat does not twist or torque. Show me a fiberglass boat that does not twist and I will show you a cocktail barge tied to the dock”.

https://hatchmasters.com/
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Old 15-09-2021, 00:36   #24
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Re: How do I make window frames for my CAL 31?

Quote:
Originally Posted by mitiempo View Post
Every hatch made (with the exception of one model of Bomar) uses acrylic.



The same goes for virtually all non-glass portlights.



The following is from Tony at Select Plastics/Hatchmasters:







01/19/20

Acrylic vs. Polycarbonate

I spend inordinate amounts of time discussing the pros and cons of acrylic and polycarbonate. In so much as I would like to bring some clarity to this issue. Please consider the following:



All major hatch, portlight, and window manufacturers use Acrylic in offshore / bluewater marine products.

Acrylic is more scratch resistant than standard (9034) polycarbonate.

Acrylic is significantly more durable when exposed to Ultra Violet radiation (sunlight).

Acrylic is less expensive than Polycarbonate.

Don’t misunderstand my preference for acrylic. I buy, use and sell a significant amount of both products and each has its application. In my humble opinion Acrylic is more durable, versatile and cost effective in the hands of a skilled craftsman than polycarbonate.



Additional considerations may include polycarbonate with UV and scratch resistant coatings. While these products are heavily promoted by several manufacturers and carry 5, 10 even 15 year warranties the following information has been reported in “real life” applications:



Polycarbonate is impact resistant. When it’s new it is almost impossible to break.

Small quantities (less than a 4 by 8) in gauges over 1/8th inch are difficult to find in the UV- scratch resistant grades.

Colors are limited. Only two standards (gray and bronze). Try and find anything thicker than 1/4 in UV/ scratch resistant!

Polycarbonate foreshortens when subject to static or dynamic loads. What this means is if you replace your hatch lens with polycarb, seal it and then step on it the ductile material will deflect (bow) in the center. One of two things may happen. 1st you will surely break the watertight seal, 2nd you may end up with a leg in your salon.

As for the warranty: The original owner is warranted against failure subject to the material being submitted to the distributor for evaluation with the original invoice subject to actual replacement cost at the time of purchase. I guess this means they sell you a new square of material and apply the old payment to the new cost. How about the labor to fabricate the part, install it and sealant? Why take the chance?

Polycarbonate is a great material; The US Air force uses it for fighter canopies! I sell Polycarb to the USCG and US Navy. Remember they don’t mind using it because we are paying to replace it every three years.

Both Acrylic and Polycarbonate have specific uses and installation requirements.



Cast Acrylic (of a specific thickness) is in accordance with CE and ABYC guidelines, and installed on virtually all of the big blue- water sail boats produced on both sides of the pond. Polycarbonate is commonly used as a replacement due to its ease of fabrication and incredible initial strength. The USCG and USN require Polycarbonate on their vessels but they also have a preventative maintenance cycle of 36 to 42 months for change out. My Tax dollars at work…



Due to its ductility Polycarbonate it is more challenging to install. I have seen Sika Flex 295UV with primer and Dow 795 both mentioned. I use and recommend both. Dont go over 4 ft continuous length with a fixed portlight. Remember the coefficient of thermal expansion for Acrylic and Polycarbonate is in the neighborhood of .000039 per inch per degree F. That means an 8ft plastic port will expand and contract up to 1/2 of an inch from the coldest day in Feb to the hottest day in summer. WOW!! Compartmentalize the job. It will be easier to install and less prone to leaks.



Never ever bolt a plastic portlight in place. Screws are fine to hold a lens till the adhesive cures. Take them out asap and fill the holes with the aforementioned products. Both of these products are rated at 700 + percent elongation before tear. Strong flexible and UV resistant.



Been to a boat show lately? Seen any screws? Glass is good so long as your boat does not twist or torque. Show me a fiberglass boat that does not twist and I will show you a cocktail barge tied to the dock”.



https://hatchmasters.com/
Hatches are different to windshields, they are likely to be walked upon and need to be more scratch resistant which speaks for the use of plexi.

Still I see no reason in doubting the research the RNLI has done before they decided to use Polycarbonate in the windshields of their lifeboats.
If they think it's good enough to protect their crews in the most horrendous situations with it, it's good enough for me.

Wether Plexi or Polycarbonate it makes sense to check on it regularly. Of course either one needs to be installed properly according to requirements.

But than each can draw their own conclusions.
Personally I stick to the suggestions of real authorities like DNV and RNLI rather than to what a single person with commercial interest in the subjects expresses.
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Old 15-09-2021, 00:57   #25
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Re: How do I make window frames for my CAL 31?

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Originally Posted by Franziska View Post
Personally I stick to the suggestions of real authorities like DNV and RNLI rather than to what a single person with commercial interest in the subjects expresses.
A single person.....as well as Lewmar, Goiot, Vetus, and every other major manufacturer of portlights and hatches.

Select Plastics/Hatchmasters is the largest repair/remanufacturing facility in North America for Lewmar.
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Old 15-09-2021, 01:33   #26
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Re: How do I make window frames for my CAL 31?

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Originally Posted by mitiempo View Post
A single person.....as well as Lewmar, Goiot, Vetus, and every other major manufacturer of portlights and hatches.



Select Plastics/Hatchmasters is the largest repair/remanufacturing facility in North America for Lewmar.
That may well be, but they are primarily focusing on hatches not windshields.

Hatches have different requirements, as they are frequently walked upon.
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Old 15-09-2021, 01:35   #27
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Re: How do I make window frames for my CAL 31?

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Originally Posted by Franziska View Post
That may well be, but they are primarily focusing on hatches not windshields.

Hatches have different requirements, as they are frequently walked upon.
And portlights - exactly what this thread is about.
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Old 15-09-2021, 05:59   #28
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Re: How do I make window frames for my CAL 31?

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Originally Posted by mitiempo View Post
And portlights - exactly what this thread is about.
Yes, but these portlights are more similar to windshields, they are not production portlights like the ones from Lewmar for example, and they will get not walked on, but might get stuffed in by wave action.

Anyway, pointless to argue further, anyone has enough info here to draw their own conclusions....
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Old 15-09-2021, 12:36   #29
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Re: How do I make window frames for my CAL 31?

Lookout Boat Window Frames - A solid solution to a leaky problem.



These guys do good work, custom fiberglass window frames.
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Old 15-09-2021, 12:40   #30
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Re: How do I make window frames for my CAL 31?

Quote:
Originally Posted by mitiempo View Post
Every hatch made (with the exception of one model of Bomar) uses acrylic.

The same goes for virtually all non-glass portlights.

The following is from Tony at Select Plastics/Hatchmasters:



01/19/20
Acrylic vs. Polycarbonate
I spend inordinate amounts of time discussing the pros and cons of acrylic and polycarbonate. In so much as I would like to bring some clarity to this issue. Please consider the following:

All major hatch, portlight, and window manufacturers use Acrylic in offshore / bluewater marine products.
Acrylic is more scratch resistant than standard (9034) polycarbonate.
Acrylic is significantly more durable when exposed to Ultra Violet radiation (sunlight).
Acrylic is less expensive than Polycarbonate.
Don’t misunderstand my preference for acrylic. I buy, use and sell a significant amount of both products and each has its application. In my humble opinion Acrylic is more durable, versatile and cost effective in the hands of a skilled craftsman than polycarbonate.

Additional considerations may include polycarbonate with UV and scratch resistant coatings. While these products are heavily promoted by several manufacturers and carry 5, 10 even 15 year warranties the following information has been reported in “real life” applications:

Polycarbonate is impact resistant. When it’s new it is almost impossible to break.
Small quantities (less than a 4 by 8) in gauges over 1/8th inch are difficult to find in the UV- scratch resistant grades.
Colors are limited. Only two standards (gray and bronze). Try and find anything thicker than 1/4 in UV/ scratch resistant!
Polycarbonate foreshortens when subject to static or dynamic loads. What this means is if you replace your hatch lens with polycarb, seal it and then step on it the ductile material will deflect (bow) in the center. One of two things may happen. 1st you will surely break the watertight seal, 2nd you may end up with a leg in your salon.
As for the warranty: The original owner is warranted against failure subject to the material being submitted to the distributor for evaluation with the original invoice subject to actual replacement cost at the time of purchase. I guess this means they sell you a new square of material and apply the old payment to the new cost. How about the labor to fabricate the part, install it and sealant? Why take the chance?
Polycarbonate is a great material; The US Air force uses it for fighter canopies! I sell Polycarb to the USCG and US Navy. Remember they don’t mind using it because we are paying to replace it every three years.
Both Acrylic and Polycarbonate have specific uses and installation requirements.

Cast Acrylic (of a specific thickness) is in accordance with CE and ABYC guidelines, and installed on virtually all of the big blue- water sail boats produced on both sides of the pond. Polycarbonate is commonly used as a replacement due to its ease of fabrication and incredible initial strength. The USCG and USN require Polycarbonate on their vessels but they also have a preventative maintenance cycle of 36 to 42 months for change out. My Tax dollars at work…

Due to its ductility Polycarbonate it is more challenging to install. I have seen Sika Flex 295UV with primer and Dow 795 both mentioned. I use and recommend both. Dont go over 4 ft continuous length with a fixed portlight. Remember the coefficient of thermal expansion for Acrylic and Polycarbonate is in the neighborhood of .000039 per inch per degree F. That means an 8ft plastic port will expand and contract up to 1/2 of an inch from the coldest day in Feb to the hottest day in summer. WOW!! Compartmentalize the job. It will be easier to install and less prone to leaks.

Never ever bolt a plastic portlight in place. Screws are fine to hold a lens till the adhesive cures. Take them out asap and fill the holes with the aforementioned products. Both of these products are rated at 700 + percent elongation before tear. Strong flexible and UV resistant.

Been to a boat show lately? Seen any screws? Glass is good so long as your boat does not twist or torque. Show me a fiberglass boat that does not twist and I will show you a cocktail barge tied to the dock”.

https://hatchmasters.com/

When I started to research what I should replace my rather big big windows with I was certain that Lexan was the strongest you could get and that was what I would get for the boat.
This post was really the first that told me that I could be wrong and researching for few more days it was obvious that I was wrong and that the best and strongest was cast acrylic.
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