Emotionally, I can’t take this anymore. (Windows)

[hgd137]

Look, bite the bullet. You are having terrible problems sealing the plastic. Once you solve that, in a relative short time you will be complaining about fogging and crazing. Change over to auto reenforced glass. It seals well and it won’t fog or craze!

[Sailor647]

It looks to us like you are using the wrong material to begin with.

Contact:

Kandice Calhoun at Multi-Craft Plastics Inc.
Kandice@multicraftplastics.com
503-352-0970
503-352-0980 fax

Multi-Craft is in Portland, Oregon, but they are extremely helpful and knowledgeable folks that have been in the plastics industry for decades. They will know what product (plastic) is best for your application / use. Things like expansion/contraction, strength, and UV resistance need to be considered.

We replace all the hatches, ports, and sidelights on our boat. Kandice was spot on in helping up pick the right material to use for replacements, which we did over seven years ago - and are still perfect and watertight. We supplied a paper or plastic pattern and measurements, and the new windows were cut perfectly to size using lasers.

We installed the sidelights with 5200 and the hatches with Sikaflex. Be sure you are cleaning the surfaces properly before applying the adhesive. If I remember correctly, one says you can't use acetone, one says not to use alcohol. Read the labels.

Best of luck.

[Chotu]

Originally Posted by sailormed

I think it is to tight in its aluminium track.
Take the sheets out of the track and see if you can shave 1/8 or less of the panels.
It can be the same vertical dimension as the old ones but maybe not have the same thermal expansion factor.
Hope you get it sorted. Chears!

No it’s collapsing under its own weight in the sun. There is already plenty of room for thermal expansion. I can easy press it flat and it slides up into the track. Then it flips back down when I let go.

[Chotu]

Originally Posted by Sailor647

It looks to us like you are using the wrong material to begin with.

Contact:

Kandice Calhoun at Multi-Craft Plastics Inc.
Kandice@multicraftplastics.com
503-352-0970
503-352-0980 fax

Multi-Craft is in Portland, Oregon, but they are extremely helpful and knowledgeable folks that have been in the plastics industry for decades. They will know what product (plastic) is best for your application / use. Things like expansion/contraction, strength, and UV resistance need to be considered.

We replace all the hatches, ports, and sidelights on our boat. Kandice was spot on in helping up pick the right material to use for replacements, which we did over seven years ago - and are still perfect and watertight. We supplied a paper or plastic pattern and measurements, and the new windows were cut perfectly to size using lasers.

We installed the sidelights with 5200 and the hatches with Sikaflex. Be sure you are cleaning the surfaces properly before applying the adhesive. If I remember correctly, one says you can't use acetone, one says not to use alcohol. Read the labels.

Best of luck.

Thanks. I’ll try this as a last ditch effort before adding 350 lbs of glass to the boat.

[Chotu]

Originally Posted by hgd137

Look, bite the bullet. You are having terrible problems sealing the plastic. Once you solve that, in a relative short time you will be complaining about fogging and crazing. Change over to auto reenforced glass. It seals well and it won’t fog or craze!

Marco Island. You get it. The sun down here can do crazy things.

I agree. But it hurts a lot to add 350lbs of glass. That’s 200 more pounds than what I have with Lexan.

[scottydaum]

I am speaking from the perspective of someone who was in the Sign Business for about 20 years and worked with a lot of different substrates that were required to be out on the elements 24/7.
The Polycarbonate I worked with was mostly LEXAN Brand. I also worked with different types of Acrylic (plexiglass) which is not as impact resistant than Lexan.
I THINK what I see is two issues.
1. The plastic looks pretty thin. Like maybe it cam e from one of the big box home supply stores. The stuff we use for signs, and what is in my boat is 1/4 inch thick. vs maybe 1/8 inch you would get at Big Box.
2. Expansion Ratio.....the expansion ratio of most plastic substrates is very high, meaning when heated by the sun it grows a lot more than you would think. I would think that the expansion ration of the plastic and the Fiberglass Rienforced Plastic would be nearly the same BUT you always need to make the window plastic much smaller than the hole it is filling.
It MUST have plenty of room on all it's sides to expand within the space it is filling.
If it is cut to fit too snuggly it will expand and bow out the way it is in the photo.
While the expansion ration of the Lexan, and the FRP may be the same, because of the difference in thickness, the thinner Lexan will heat or cool faster/slower than the surrounding FRP. The final expansions may be nearly the same but the time it takes to get there is different and causes problem.
The bedding/sealant/adheisive used to hold the plastic in place also need to remain flexible enough to adapt to the expansion without losing it's bond. Others will have better ideas of what product is better for that.
On my Tartan 30 the port lights (1/4 inch Lexan) are held in place by an inner and outer bezel which is bonded with butyl tape, and thru bolted. The wholes also need to be drilled oversized to allow for expansion.
I suggest you find a Plastic Supply House, or maybe even a local Electrical Sign Maker to source your plastic.That way you can access different thickness plastic, as well as folks who understand the material. You can also get plastic which is darker, or different colors.
One caution.....acrilic plastic, and polycarbonate are two different animals and different chemicals effect them differently causing premature brittleness, cracking, crazing, and frosting. Best of luck with you.

[skyhawk]

bowing to me says that something is trying to expand/contract but is being held tight.

It WILL expand and contract....or break, so don't hold it tight.

I don't fully have my head wrapped around your situation/construction.....
but maybe something more flexible....like a butyl sealant perhaps...might be better than an adhesive/tape ?

[TrentePieds]

Chotu:

You've chosen the wrong material for this application. Tempered glass has a Coefficient of Expansion of about 6. Polycarbonate has a Ec of ten times that. The Ec is an inate characteristic of the material that you cannot change, and the forces involved in the expansion are greater than you can contain.

If you confine a sheet of polycarbonate by using mechanical fastenings at the edges, the sheet will pop the fastenings and buckle (as yours seem to have done). If you use adhesive along the edges, the adhesive will tear. The forces of expansion are simply larger than you can contain. Thus you can never hope to get a watertight mounting if you try to use polycarbonate.

Glass, OTOH, moves so little that adhesive - butyl tape - can accommodate the movement. When the pane is then held in place by a by a simple coaming the change in dimensions is absorbed by the flexing of the tape.

Best bite the bullet and rethink the job, methinks!

All the best

TrentePieds

[jooa]

"Polycarbonate expands in hot weather and contracts in cold - about 1/32" per foot for 100° of temperature change with the greatest amount of movement during the spring and fall seasons." ( from internet)



Can you cut the windows slightly smaller to accommodate the expansion? Or use smaller size panels? An 8 ft length of polycarbonate could expand/contract 1/2" over the course of a cold to hot day.

[sepharad]

1) I am no plastics wizard.
2) I am from Portland originally and Multi-craft has been a staple there since I was a small child. They are real pro's.
3) Either the material is not appropriate for the application....OR the area framing the window is expanding and contracting more. (I tend to think it's the material)
4) I would call multicraft. We have a strong marine/river boating presence in Portland. We get almost as much heat in summer (shorter duration) and much colder in winter.
5) If they don't have a solution, I would consider custom cut and tempered or safety Glass.

If there was a Poly that worked in that location previously, there should be an effective replacement material.

I am sorry for your grief. What a pain. Good luck.

[chowdan]

Couldn't agree more. Contact a local glass shop that specializes in replacing window IGU's. Their suppliers should be able to supply single sheets of tempered glass.

I believe it should be around $2.50/sqft for 1/4" tempered glass.

A shop I used to manage before starting my own was a franchise called the glass guru, they are all over the us so that may be a good start for you to get an idea of what type of outfits can help

Originally Posted by TrentePieds

Chotu:

You've chosen the wrong material for this application. Tempered glass has a Coefficient of Expansion of about 6. Polycarbonate has a Ec of ten times that. The Ec is an inate characteristic of the material that you cannot change, and the forces involved in the expansion are greater than you can contain.

If you confine a sheet of polycarbonate by using mechanical fastenings at the edges, the sheet will pop the fastenings and buckle (as yours seem to have done). If you use adhesive along the edges, the adhesive will tear. The forces of expansion are simply larger than you can contain. Thus you can never hope to get a watertight mounting if you try to use polycarbonate.

Glass, OTOH, moves so little that adhesive - butyl tape - can accommodate the movement. When the pane is then held in place by a by a simple coaming the change in dimensions is absorbed by the flexing of the tape.

Best bite the bullet and rethink the job, methinks!

All the best

TrentePieds

[Chotu]

Originally Posted by scottydaum

I am speaking from the perspective of someone who was in the Sign Business for about 20 years and worked with a lot of different substrates that were required to be out on the elements 24/7.
The Polycarbonate I worked with was mostly LEXAN Brand. I also worked with different types of Acrylic (plexiglass) which is not as impact resistant than Lexan.
I THINK what I see is two issues.
1. The plastic looks pretty thin. Like maybe it cam e from one of the big box home supply stores. The stuff we use for signs, and what is in my boat is 1/4 inch thick. vs maybe 1/8 inch you would get at Big Box.
2. Expansion Ratio.....the expansion ratio of most plastic substrates is very high, meaning when heated by the sun it grows a lot more than you would think. I would think that the expansion ration of the plastic and the Fiberglass Rienforced Plastic would be nearly the same BUT you always need to make the window plastic much smaller than the hole it is filling.
It MUST have plenty of room on all it's sides to expand within the space it is filling.
If it is cut to fit too snuggly it will expand and bow out the way it is in the photo.
While the expansion ration of the Lexan, and the FRP may be the same, because of the difference in thickness, the thinner Lexan will heat or cool faster/slower than the surrounding FRP. The final expansions may be nearly the same but the time it takes to get there is different and causes problem.
The bedding/sealant/adheisive used to hold the plastic in place also need to remain flexible enough to adapt to the expansion without losing it's bond. Others will have better ideas of what product is better for that.
On my Tartan 30 the port lights (1/4 inch Lexan) are held in place by an inner and outer bezel which is bonded with butyl tape, and thru bolted. The wholes also need to be drilled oversized to allow for expansion.
I suggest you find a Plastic Supply House, or maybe even a local Electrical Sign Maker to source your plastic.That way you can access different thickness plastic, as well as folks who understand the material. You can also get plastic which is darker, or different colors.
One caution.....acrilic plastic, and polycarbonate are two different animals and different chemicals effect them differently causing premature brittleness, cracking, crazing, and frosting. Best of luck with you.

Thank you, Scotty! I’ve been praying a glazier or sign maker would respond some day.

I bought all the 1/4” UV protected polycarbonate directly from Sabic when I put it on the first time.

The first time, I used epoxy coated wood Z channels I made up. It did well. Lasted a few years and then the wood started rotting away and eventually did.

Then I started down the dark path of Dow 795 and the thickest VHB tape made by 3m. I used all the primers and everything. The complete system.

Every 6 months to a year the windows would start falling off. Tried every technique under the sun with the same results.

After this last summer away from the boat, one is the widows was completely gone to Davy Jones. So I had to get some new polycarbonate on there. I came back to a flooded boat because a damn rat or whatever chewed my solar wire. Destroyed batteries too.

So I replaced all that and got the water out and stuff.

I went to source some new Sabic 1/4” I’ve protected polycarbonate and nope! Maybe next year they’ll have some. Gotta love building boats during Covid.

So I bought the ONLY sheet of 1/4 UV protected polycarbonate in stock at a plastic specialty shop (who makes all those sneeze guards for Covid now).

It had no brand. And here it is collapsing under its own weight in the sun.

It’s not in there tightly and it has plenty of thermal expansion room.

I think I need to go with glass. I can’t do this anymore.

[Cpt Mark]

Originally Posted by Woodland Hills

This is why you do not see plastic windows on production boats. The expansion is too great for effective sealing. You need to bite the bullet and pony up for high strength glass.

Disagree. Large production cats all have these windows. Long, huge etc. And some have compound curves to boot.

I'm having a hard time believing the issue is the weight of the poly. You can test this theory out easy enough. Take a new window and set it next to where it's going to go in but not in the frame. If the next day it's bowed out then I'm wrong but given that your boat used to have these and others are still made this way I'm betting it won't be bowed.

That leaves you with installation. Maybe you're too tight and with expansion it's hitting and stopping on the edges of your aluminum track and then because it has to expand it bows out. If you think this is the case then trim some off the edge and try again.

Good luck.

[Chotu]

Originally Posted by TrentePieds

Chotu:

You've chosen the wrong material for this application. Tempered glass has a Coefficient of Expansion of about 6. Polycarbonate has a Ec of ten times that. The Ec is an inate characteristic of the material that you cannot change, and the forces involved in the expansion are greater than you can contain.

If you confine a sheet of polycarbonate by using mechanical fastenings at the edges, the sheet will pop the fastenings and buckle (as yours seem to have done). If you use adhesive along the edges, the adhesive will tear. The forces of expansion are simply larger than you can contain. Thus you can never hope to get a watertight mounting if you try to use polycarbonate.

Glass, OTOH, moves so little that adhesive - butyl tape - can accommodate the movement. When the pane is then held in place by a by a simple coaming the change in dimensions is absorbed by the flexing of the tape.

Best bite the bullet and rethink the job, methinks!

All the best

TrentePieds

Agreed. Hope I can make up the 300 lbs of glass somewhere

[MicHughV]

perhaps the solution is to make a strong frame and place it over the product....the window can then get bedded in, and the frame can be mounted over the window with screws...a teak frame ???

from experience in trying to remount the large plexiglass/lexan window on my Beneteau, I had to go thru a variety of caulking sealants before I found one that worked...it was not a Home Depot product.....can't remember the name now but had to go to specialty store to find it..