Hi all,
I am going to replace the two fixed windows on our cabin. I have been advised by some suppliers that I should use Acrylic Perspex, and other suppliers say Polycarbonate. Has anyone any experience with either of these materials.
I will be fitting them myself and have taken plywood templates.

Feedback would be appreciated.

Thanks 

Brian S/V Darramy 

+x

 

bwallace - 16 Nov 2021

Hi all,
I am going to replace the two fixed windows on our cabin. I have been advised by some suppliers that I should use Acrylic Perspex, and other suppliers say Polycarbonate. Has anyone any experience with either of these materials.
I will be fitting them myself and have taken plywood templates.

Feedback would be appreciated.

Thanks 

Brian S/V Darramy 

Hi Brian,
My take is that polycarbonate is quite a bit stronger and less likely to crack under impact. Not sure why anyone would suggest acrylic for a window on a sea-going boat unless it was in a protected area and one was worried about scratches: polycarbonate scratches more easily. With both you must be careful with the bedding choice as some caulk/bedding is not compatible. I believe polycarbonate is easier to work also, but I am less sure about that. I also think some polycarbonate is formulated to be UV resistant.
My info may be a bit dated, so please check it out, My best, Dick Stevenson, s/v Alchemy

Hi Brian,
I don't know the answer to your question but I have found the people at Eagle boat windows are most helpful with any questions about windows or hatches.
Martin

Hi Brian, 

I replaced the old acrylic pilothouse windows on my boat with polycarbonate, because it is stronger (I think this is because it flexes more to take a load than acrylic does, so scratches easier but avoids breaking better).

I actually replaced the windows twice, because I made the mistake of putting RainX (designed for car windshields to cause rain to wash off quicker) on the new windows. This destroyed the UV coating (polycarbonate slowly goes cloudy when UV damaged), and within a few years I replaced the windows again. So don't ever do that :)

I've used neoprene gaskets to seal the windows, and they worked well. I've also used polyurethane adhesive sealants, whatever was available at the time, a Sikaflex, LePage's Quad, Wang Xin [I got that in Chile from a automobile glass shop--it was the only thing available that would set at temperatures below 10C] and a Brazilian one.  All the polyurethane adhesive sealants that I used worked well.

If your windows are bolted on, as opposed to glued into a frame, it's important that the holes drilled in the polycarbonate need to be at least twice the diameter of the bolts, otherwise different expansion rates will result in cracks around the bolts after several weeks.

It occurs to me that if you have the type of windows that go into an extruded aluminum frame, held on both sides by a little lip, it is possible that they are designed for the stiffness of acrylic.

If you're buying from a non-marine supplier, you'll want to confirm that the polycarbonate they sell has a UV coating on it.

This is a follow up on my replacement window post last year.
I have now successfully installed two new windows in the sides of the coach roof of the saloon on Darramy.
This follow up may help someone else on the forum looking to do a similar project.
Templates were taken first with paper onto cardboard, then transferred to plywood.
The existing windows installed by Beneteau in 1986 were a fixed pane with an aluminium frame on both the outer and inner sides fastened together with inter bolts. The problem I had was I did not know what was between the frames apart from my extremely fractured Perspex window. So after a fair bit of research and guidance from “Eagle Boat Windows UK” help notes, I followed their advise and did not use Mastic. I used Scapa 3507 tape obtained from “Affix.CO.UK”. Now at this time I knew once I removed the old frames and Perspex I was committed, so I obtained all materials I hoped I would need in the UK and built a wooden box to transport by air back to Greece. I did in reserve bring two tubes of Marine Clear Acrylic Mastic just in case though!
Many of the existing inter bolts were corroded onto the outer frame and working from inside I had to drill the heads off. Once all heads were removed I was able to prise the outer frame away from Perspex. Then remove the Perspex. What amazed me once removed that these windows installed in 1986 were sealed in with Scapa (or French equivalent) Tape. Exactly what I had bought.
Once the exterior was cleaned off with Acetone I was able to stick the Scapa tape around the aperture. All drilling was done on the new windows from inside using the existing holes with just a pilot hole, then a 6.7mm hole (for the female part of the inter bolt)drilled from the outside inwards, thus avoiding any splintering of the Perspex on the exterior surface.
The existing inner frame was left in place, and used to refasten the inter bolts, and hide all joins as originally constructed.
I did put a small amount of Mastic on each Inter bolt from the exterior to ensure I had a fully watertight seal.
Now a few weeks later, I am pleased to report the windows have proved to be fully watertight, and a successful project. The bonus is we can now see clearly out of the new windows!
Brian C Wallace
S/V Darramy

+x

 

bwallace - 29 Apr 2022

This is a follow up on my replacement window post last year.
I have now successfully installed two new windows in the sides of the coach roof of the saloon on Darramy.
This follow up may help someone else on the forum looking to do a similar project.
Templates were taken first with paper onto cardboard, then transferred to plywood.
The existing windows installed by Beneteau in 1986 were a fixed pane with an aluminium frame on both the outer and inner sides fastened together with inter bolts. The problem I had was I did not know what was between the frames apart from my extremely fractured Perspex window. So after a fair bit of research and guidance from “Eagle Boat Windows UK” help notes, I followed their advise and did not use Mastic. I used Scapa 3507 tape obtained from “Affix.CO.UK”. Now at this time I knew once I removed the old frames and Perspex I was committed, so I obtained all materials I hoped I would need in the UK and built a wooden box to transport by air back to Greece. I did in reserve bring two tubes of Marine Clear Acrylic Mastic just in case though!
Many of the existing inter bolts were corroded onto the outer frame and working from inside I had to drill the heads off. Once all heads were removed I was able to prise the outer frame away from Perspex. Then remove the Perspex. What amazed me once removed that these windows installed in 1986 were sealed in with Scapa (or French equivalent) Tape. Exactly what I had bought.
Once the exterior was cleaned off with Acetone I was able to stick the Scapa tape around the aperture. All drilling was done on the new windows from inside using the existing holes with just a pilot hole, then a 6.7mm hole (for the female part of the inter bolt)drilled from the outside inwards, thus avoiding any splintering of the Perspex on the exterior surface.
The existing inner frame was left in place, and used to refasten the inter bolts, and hide all joins as originally constructed.
I did put a small amount of Mastic on each Inter bolt from the exterior to ensure I had a fully watertight seal.
Now a few weeks later, I am pleased to report the windows have proved to be fully watertight, and a successful project. The bonus is we can now see clearly out of the new windows!
Brian C Wallace
S/V Darramy

Hi Brian,
Great report: I am sure you will save someone research and consternation and errors.
My best, Dick Stevenson, s/v Alchemy