Best long-term window material choice?

[SunnySky]

I have four pilothouse windows which I replaced less than 6 years ago that already have one crack over 6" and two cracks about 2.5" long along with extensive crazing which to me seems like an overly short lifespan for 1/2" AR-2 polycarbonate. I realize the intense Hawaiian sun my hatches/windows have had to deal with can be pretty hard on polycarbonate and acrylic but given that I installed 10 new hatches which are still fine prior to replacing these four windows it seems like the coating (which was not damaged...) should have protected the underlying polycarbonate much better and I really want to choose a longer-term solution but after all my research the first time around I'm not aware of an option I can reasonably expect to be better than what I did before.


In terms of mounting details from less than 6 years ago:
The windows are not simple rectangles but for the purposes of giving an approximate size two about 24” x 37” and two about 24” x 34” with about 2 1/4" of their perimeter mounted with Sikaflex 295 UV after lightly sanding the surface to be bonded and using Sika Primer 2009 D and Sika Primer 215. All products used were not expired and from fresh containers. All corners are about 2" radius and there are no drill holes or mechanical fasteners to cause a stress concentration. I made sure to have an even film thickness. I was under the belief I was getting Marolon AR from Professional Plastics Inc aka proplas.com but currently on their website I noticed a disclaimer that "Makrolon® AR is our preferred brand, but some items sold on this page may vary."


I honestly am not 100% sure if what I last installed was Makrolon or not, or if the proplas website had the disclaimer of possibly substituting brands at the time of my two purchases (one prior to sailing north from Bellingham and one when I was anchored off of california and actually finally getting around to installing them..).


Either way I have a hard time with Professional Plastics response that "The life span of Polycarbonate is 5-7 years in direct sun / around water with more intense UV rays it maybe less. Your material also had a AR2 Coating which is a factory spray on coating, when you sanded the material you also sanded off the coating and once you added any kind of primer or modified the material that invalidated any warranty."


Given how good all 10 of my cast acrylic hatches still look it's tempting to go with cast acrylic for these windows this time around BUT I'ver heard from multiple people that sound like they know what they are talking about that the AR-2 polycarbonate is a better choice for this application and that it should last MUCH longer than it did?
Any thoughts?

[CarlF]

Glass.

https://setsail.com/glazing/

[slug]

Originally Posted by SunnySky

I have four pilothouse windows which I replaced less than 6 years ago that already have one crack over 6" and two cracks about 2.5" long along with extensive crazing which to me seems like an overly short lifespan for 1/2" AR-2 polycarbonate. I realize the intense Hawaiian sun my hatches/windows have had to deal with can be pretty hard on polycarbonate and acrylic but given that I installed 10 new hatches which are still fine prior to replacing these four windows it seems like the coating (which was not damaged...) should have protected the underlying polycarbonate much better and I really want to choose a longer-term solution but after all my research the first time around I'm not aware of an option I can reasonably expect to be better than what I did before.


In terms of mounting details from less than 6 years ago:
The windows are not simple rectangles but for the purposes of giving an approximate size two about 24” x 37” and two about 24” x 34” with about 2 1/4" of their perimeter mounted with Sikaflex 295 UV after lightly sanding the surface to be bonded and using Sika Primer 2009 D and Sika Primer 215. All products used were not expired and from fresh containers. All corners are about 2" radius and there are no drill holes or mechanical fasteners to cause a stress concentration. I made sure to have an even film thickness. I was under the belief I was getting Marolon AR from Professional Plastics Inc aka proplas.com but currently on their website I noticed a disclaimer that "Makrolon® AR is our preferred brand, but some items sold on this page may vary."


I honestly am not 100% sure if what I last installed was Makrolon or not, or if the proplas website had the disclaimer of possibly substituting brands at the time of my two purchases (one prior to sailing north from Bellingham and one when I was anchored off of california and actually finally getting around to installing them..).


Either way I have a hard time with Professional Plastics response that "The life span of Polycarbonate is 5-7 years in direct sun / around water with more intense UV rays it maybe less. Your material also had a AR2 Coating which is a factory spray on coating, when you sanded the material you also sanded off the coating and once you added any kind of primer or modified the material that invalidated any warranty."


Given how good all 10 of my cast acrylic hatches still look it's tempting to go with cast acrylic for these windows this time around BUT I'ver heard from multiple people that sound like they know what they are talking about that the AR-2 polycarbonate is a better choice for this application and that it should last MUCH longer than it did?
Any thoughts?

It’s posdible that the windows were not installed correctly or that your boat has a lot of movement

How thick were your bond lines

Are the windows molded to shape or is the surface absolutely flat

[SunnySky]

Thank you both for your quick replies,
CarfF: I've definitely considered glass, although weight and ultimate strength given impact of a failure has me really wanting to stick with a suitable plastic (but I'm not yet ruling glass out...)


Slug: The windows were installed flat and I just double checked the window openings as to how "absolutely" flat they are, and they are all within 1/16" of perfectly flat and generally closer to 1/32" or less (over a 3' distance). Bonding surface was around 2 1/4" wide but I don't recall the exact thickness other than that I used a handful of thin green felt spacers to keep a consistent film thickness and that I cut the tip of the tube to make the beads according to the sikaflex directions.



In relation to possibility of my boat having extensive movement, I don't believe where they were mounted gets enough movement to be an issue but even if there were a lot of movement don't you think the polycarbonate should bend as opposed to cracking?


Thank you for helping me think through this,

[Minggat]

There is a huge difference between the durability of extruded acrylic and cast acrylic. Cast acrylic has been reported on this forum to look brand new after 20 years.


Makralon is great stuff for dodger windows, but also has it's aging characteristics.


Having learned all of this the hard way, when I built the hardtop for my dodger, I used Makralon again, but I made my windows removable. Now they all live inside the boat, overhead and out of the way, against the underside on my cabin top. They get deployed on passages, so will live mostly out of the sun and likely outlive me. My boat is my home, so when I say "out of the way", that is required.

[slug]

Originally Posted by SunnySky

Thank you both for your quick replies,
CarfF: I've definitely considered glass, although weight and ultimate strength given impact of a failure has me really wanting to stick with a suitable plastic (but I'm not yet ruling glass out...)


Slug: The windows were installed flat and I just double checked the window openings as to how "absolutely" flat they are, and they are all within 1/16" of perfectly flat and generally closer to 1/32" or less (over a 3' distance). Bonding surface was around 2 1/4" wide but I don't recall the exact thickness other than that I used a handful of thin green felt spacers to keep a consistent film thickness and that I cut the tip of the tube to make the beads according to the sikaflex directions.



In relation to possibility of my boat having extensive movement, I don't believe where they were mounted gets enough movement to be an issue but even if there were a lot of movement don't you think the polycarbonate should bend as opposed to cracking?


Thank you for helping me think through this,

Your installation sounds correct

Polycarbonate will not bend

Normally the more movement you expect the thicker the bond line

Do you have any gel coat spider cracks in the area of the windows ?

The gel spiders normally indicate movement of the glass laminate

Flexing

[SunnySky]

Thank you,


Minggat:
When if comes to a dodger I really like your designing them to be removed when not needed. While unfortunately this is not an option for me given it being more of an interior pilothouse area. it does make me think about various ways of having the windows shaded the vast majority of the time. Something along the lines of removable storm-board made out of divinycell that does double duty under reasonable conditions as a window overhang. My main hesitation is that I'm leery of losing the situational awareness that comes with being able see 360 degrees around my boat whether I'm actively sailing or anchored out somewhere which means my the time I built it as strong as I would need it to be I would likely be at or above the same weight as glass (although the extra weight of glass wouldn't include the additional insulation value or shade that the stormboard option would...).


What made you choose to go with Makralon vs a cast acrylic? Also even with the impact of UV somewhere with the sun is as intense as Hawai'idoes having a less than 6 years lifespan of new AR2 polycarbonate window seem within a normal range?


slug:
I have polyurethane paint so unfortunately certain stresses would be more difficult to see than with gelcoat but since that is one of the few areas of my boat that I did not yet repaint since I bought my boat used 9ish years ago the paint is undeniably in need of being redone but its seems mostly due to simple age (possibly as old as 16 years), as opposed to what may be from too much flex. But since it doesn't hurt to add some additional stiffness surrounding the windows this time around simply for extra piece of mind.

[Adelie]

Tempered glass.

[contrail]

Originally Posted by slug

Your installation sounds correct

Polycarbonate will not bend

Normally the more movement you expect the thicker the bond line

Do you have any gel coat spider cracks in the area of the windows ?

The gel spiders normally indicate movement of the glass laminate

Flexing

I believe that polycarbonate WILL bend, quite easily. In fact, I have a piece in front of me that does so. That's part of its strength.

[slug]

Originally Posted by contrail

I believe that polycarbonate WILL bend, quite easily. In fact, I have a piece in front of me that does so. That's part of its strength.

You will build up international stress in the panel

Over time This stress will become cracks

If your cabin house profile I’m not flat you must relieve the stress by heat forming the plastic to the correct shape

You could Consider your polycarbonate to be glass

For none heat formed windows I’ve had good luck bending lexan

Over time it to will also crack , But it seems to take many years

Lexan has its own disadvantage in that its rather soft and UV. burns it yellowish



What type boat is this .. builder

[SunnySky]

Roger Simpson 12.2 Meter catamaran, owner-built out of British Columbia launched around 2004 and I am the 2nd owner.



In the course of this overhaul I've been pretty diligent about shedding unnecessary weight (so in a sense I could afford adding some extra weight back going really thick tempered glass although I'm still relatively biased towards lighter options..)

[wrwakefield]

Our Nauticat 43 pilothouse ketch still has all the original tempered glass ports, hatches, windshield and windows from 1983. She spent 15 of those years in the tropics. with a UV filter film applied to the inside surfaces of the pilothouse windows (but not windshield panels.)

If I needed to replace any today, I would go with double pane tempered glass only because we prefer mid and high latitudes...

Just another data point for your consideration...

Cheers! Bill

[JPA Cate]

@SunnySky,

Friends with polycarbonate dodger windows (it is an aluminum mono, and I'm pretty sure the dodger doesn't move) have had them for over 20 years. It does go funny over time, and one uses the polish on it that one uses on the lenses over car headlamps to get it clear again. No cracking, ever. My guess is that Slug is onto something relative to the installation, or the pilot house itself.

Good luck with it. I hope you can find a better company to deal with.

Ann

[slug]

Originally Posted by SunnySky

Roger Simpson 12.2 Meter catamaran, owner-built out of British Columbia launched around 2004 and I am the 2nd owner.



In the course of this overhaul I've been pretty diligent about shedding unnecessary weight (so in a sense I could afford adding some extra weight back going really thick tempered glass although I'm still relatively biased towards lighter options..)

I don’t know catamarans so it’s hard for me to visualize your windows

Did you need any clamping pressure to seat the windows

As far as glass .. it’s s bad choice for small craft

Heavy and fragile

I’ve also had to repair broken tempered glass windows on yachts

[HBrew]

I have these shades which snap around the window edges. They keep the sun out but you can see through them - they are a fine mesh. Maybe something like this would help preserve your windows?