Glass windows?

[mvweebles]

If it's only 11-12 years old, is the builder still in business? If so, have you reached out to them?

[Epicurean]

Originally Posted by mvweebles

If it's only 11-12 years old, is the builder still in business? If so, have you reached out to them?

Ask him what? These are mostly custom built boats. They probably did what seemed reasonable. But over the 12 years hasn't held up. What I want is to find someone who has expert knowledge about how things should be done.

[Constellation49]

The process for drape moulding acrylic is fairly simple. See photos of the entire process from building mould and oven to the completed 3/4” thick product.

Proper care for acrylic is essential to keep the clarity. I have always used Plexus but there are other brands that are as good. Never use any household cleaners, only products fit for purpose.

[Sailorman Ed]

Constellation - outstanding job! I assume you used cast acrylic? How hot did you get the oven and how long?
Ed

[Constellation49]

Ed,

Yes, cast acrylic. https://www.mcmaster.com/8560K368/

We heated it to 350f and maintained that temperature for 1 hour. You can see from the photos it was very flexible. This temperature and time frame is based on the thickness of the material. There are formulas you can retrieve on the internet that provides guidance.

I placed another mould on top of it and held It down with multiple clamps with even pressure as it cooled. You could hear it shrinking inside the mould as it cooled.

With the exception of all the hatches this is the only acrylic. The remaining windows are all tempered marine glass 3/4” thick with a free floating 1/4” pain to provide insulation. These were provided by FabTek out Washington state. All these have no curvature. https://www.fabtekind.com/

[Epicurean]

Originally Posted by Constellation49

The process for drape moulding acrylic is fairly simple. See photos of the entire process from building mould and oven to the completed 3/4” thick product.

Proper care for acrylic is essential to keep the clarity. I have always used Plexus but there are other brands that are as good. Never use any household cleaners, only products fit for purpose.

Thanks! I'm not quite clear. You built a mold for both top and bottom. Then heated it in an oven. After it draped and cooled you removed it from the mold and it was the finished window?
How long ago was that? Was there any subsequent crazing? How are the optical properties now?

[Constellation49]

I built a mold by using the aluminum “lip” of the window frame. I used 3 layers of thinnest plywood I could find and laminated them together using glue into the window frame. Once the glue dried I removed and added braces to the backside as well as enlarged it a bit. I then glazed it with epoxy and body filler for fill in any irregularities. I cut the acrylic a bit oversized for the actual opening. Heated it in oven pulled it out and placed on mold. I then placed another sheet of thin plywood on top of the acrylic that was draped over mold. This plywood was held in place with clamps. Between the wood mold I used a cotton bed sheet to prevent scratching of the soft acrylic.

I performed all these activities between Aug and Oct of 2022. I installed the acrylic window into the frame using SikaFlex components as directed by there guidance. I still need to paint the outside perimeter of the acrylic to prevent UV rays from degrading the adhesive. I will perform this activity once I install the trim to the inside so I will know the boundaries of my border.

Optically it is not as good as glass but excellent for 3/4” thick acrylic. Not sure the thickness you desire. We first used 3/16” thick acrylic as a trial run and to get a final cut template of the thicker acrylic once molded. You can see in photo the thickness of the acrylic is 3/16 thick, “test run”.

The key is the building the mold for the opening. Finding a glass manufacturer to build a custom curved glass that will fit your opening will be very difficult. Not saying impossible just difficult.

I hope this explains things better.

[skipperpete]

Excellent work Constellation49. I was involved in a project to make Robinson helicopter “windscreens” out of Lexan using a similar oven technique but in this instance it was a spectacular failure, the shape was good but the optical quality was very poor and eventually they abandoned Lexan for acrylic. ......success. And the same optical issue arose with a high speed motor cruiser I once delivered, it had a 2 piece compound curve glass windscreen on the upper deck specifically moulded for that vessel and inclined at a fairly steep angle across the width of the flybridge, it looked really beautiful and was astonishingly expensive but underway the optics of it caused the oddest dizziness and nausea and I had to look over the top of it to avoid seasickness.

[Epicurean]

Originally Posted by Constellation49

I built a mold by using the aluminum “lip” of the window frame. I used 3 layers of thinnest plywood I could find and laminated them together using glue into the window frame. Once the glue dried I removed and added braces to the backside as well as enlarged it a bit. I then glazed it with epoxy and body filler for fill in any irregularities. I cut the acrylic a bit oversized for the actual opening. Heated it in oven pulled it out and placed on mold. I then placed another sheet of thin plywood on top of the acrylic that was draped over mold. This plywood was held in place with clamps. Between the wood mold I used a cotton bed sheet to prevent scratching of the soft acrylic.

I performed all these activities between Aug and Oct of 2022. I installed the acrylic window into the frame using SikaFlex components as directed by there guidance. I still need to paint the outside perimeter of the acrylic to prevent UV rays from degrading the adhesive. I will perform this activity once I install the trim to the inside so I will know the boundaries of my border.

Optically it is not as good as glass but excellent for 3/4” thick acrylic. Not sure the thickness you desire. We first used 3/16” thick acrylic as a trial run and to get a final cut template of the thicker acrylic once molded. You can see in photo the thickness of the acrylic is 3/16 thick, “test run”.

The key is the building the mold for the opening. Finding a glass manufacturer to build a custom curved glass that will fit your opening will be very difficult. Not saying impossible just difficult.

I hope this explains things better.

Again, Thanks! I'm wonder how the acrylic will age. Yes, the mold is the critical part. And for glass, the window can't be made oversize, then cut down. But mine sit on top of the structure, not in a frame. So a little slop might be OK. Hopefully, I'll meet someone who knows a "trick" that'll make it easier. I should have talked more with the girl I was hauled out next to who did it.

[Talbot]

Flat windows - glass if the weight is ok.

Curved windows - acrylic and do it befor the old ones crack so you can use them to create the mould for the new ones.


If you cover the windows in shade cloth, they will last much longer. I have large windows that are acrylic and now 23 years old. no cracks. But had to replace hatch windows that were badly crazed.

[TabbyCat]

Originally Posted by Epicurean

I need to replace curved windows on my aluminium catamaran. The acrylic is 11 years old and it has a lot of microcrazing that makes them pretty opaque. It also has some other scratches and distortions. I'm thinking of going to glass and am interested in experiences others may have had with it, in outcomes, and having it fabricated. I am aware that glass can shatter, as can acrylic under different conditions. Also, glass is heavier and has different thermal expansion properties. I also don't think polycarbonate is what I'm looking for. I'm tired of boats with windows with poor optical properties. Then, too, there are different types of glass; tempered, toughened and laminated.
Of course, a big question is who can do it?

Try SeaMac in NZ. They ship worldwide. We had ours done while we were there, but you can get a local installer to put them in. We have all around glass on our Cat, with 4 opening windows in front and a locking french door in the back. It made a huge difference to the comfort of the boat, dry inside, no more foggy plastic. Our front windows are 8mil, the sides are 6.

I never did understand why so many people put shades on the outside of their catamaran windows. You would not put curtains on the outside of your house do you? Shades / curtains should be inside - if outside, they imprint on the plastic or glass and get dirty. If inside, they are much easier to roll up and they stay clean.

[pbmaise]

You could work with a custom glass firm that specializes in working on vintage cars.

https://www.curvedglasscreations.com/custom-auto-glass

They can produce a nice curved tempered glass window.

However, I highly doubt it is worth the investment.

I bet you will find you can take a wide long curve and break it up into a few flat sections. You just need to add some fiberglass dividers and accept the fact it isn't as pretty as the curve. This would be far cheaper than working with a custom glass shop and provide a lasting solution both you and a future owner will appreciate.

[danstanford]

Often the crazing is as a result of the cleaners used. Windex is the worst thing you can use and it is often a go to for those unaware.

[bcboomer]

This company:
https://coastalcurvedglass.com/marine-transport/
They also have a lighter version of glass suitable for marine installations. You may be able to send them your old windows to use for patterning.
Probably expensive but, if it's your home, why not?

[Cpt Mark]

I used to Captain a 55' catamaran tour boat years ago. Spoke with the owner recently and got caught up. They replaced all the plastic windows with glas and never looked back. Said it was the best decision they'd ever made. The glass co. is located on the E coast of USA and flew their team to the W coast for measuring etc. Expensive but done to perfection.

My cat also has a 90 curve to with a compound bend. And the plastic was cracked. I can also see where the the other side will crack. My front windows are 2 piece, 1/2" thick. I found a company that will do thermoforming of the plastic. Hellaciuosly expensive and that's with me making the molds. Instead, I am going to modify my boat. I plan to add foam/glass to take all the curve out of the front so I can just put in a flat piece of material. On the side it it pretty flat as it is so no worries. As far as the 90 degree curve that will be foam/glass and painted or gel coated a similar color as the new windows. It will look very similar to what I have now but easy to replace the windows. My side windows btw are 9' long. Those will be modified into 2 separate windows.