Big plexi glass mounting question

[flemmingsveen]

Hi
I have been thinking for a long time on a solution of how to mount my new wide frond deckhouse window. Its 50cm high and maybe around 2,40 wide.
It used to have three windows but now one wide.
Becouse its big and long it is going to expand and shrink 5mm on each side at the most. So I have been thinking of mounting clamps in each end. Either drill holes in the plexi or just make grooves and glue it. Seems like the safest way is 5 bolts on each side ends. the long sides I was thinking of skipping bolts. Because the pressure will be enuff(beacause the curving of the window). Just some guides will do. I dont want hundred of bolt like last time... cracks when get from hot to cold areas

I havent decided how the clamp would be made but the principle is shown on the drawings.

Another thing is what gasket to use. I want a thick gasket and dont want to use any sealent like 4200 etc. hopefully I can find one that is made for this type of mounting. If not I will look for a round 12mm one to squeeze around the edges.

Any good advises?

[stoupidmonkey]

There is a guy at my marina that replaced his plexiglas without frames and just used a compound that builders use to put in windows on skyscrapers. He made the plexi larger than the holes, glued it in and put a gasket on the outside. Its been working out fine for the past 10 or so years. The compound will allow for movement, as to not hurt the plexi.

[irwinsailor]

I did my new windows using the sika flex system. There are no fasteners.

[Stillraining]

Flem.

Good idea on the clamping system...however your drawing not being to scale I think you are going to find out that less then 1/2 penetration of thread is not going to hold up to the load your asking.

IMHO.....I think you better plan on through drilling and possibly rubber grommets to protect the hole and outside bearing surface for a large pan head ( carriage bolt type) applying the pressure and weight holding capacity's.

OH ..PS; If you want thoes exact style of clamps made from aluminum PM me

[Christian Van H]

I believe Stillraining is right. The Dashews recommend a frame on the outside, thru-bolts, and a rubber or sealant gasket between Lexan / Plexi and cabin side. Here, a pics worth a thousand words...

[vacendak]

flemmingsveen,

am in process of solving the same problem
unfortunately cannot read your pictures - too small they are - to say anything certain

[GordMay]

PLEXIGLAS GLAZING DETAILS AND INSTALLATION:
Altuglas International: Europe/Americas/Asia: Glazing Details and Installation

From:
Plexiglas® Acrylic Sheet in Architecture:
Altuglas International: Europe/Americas/Asia: Technical Data

[flemmingsveen]

Ok here I got alot of info. Thanks!

the frame drawings in the links from GordMay I like. But here in St.Vincent its not easy to get aluminium profiles. To use on the outside.
I cannot use bolts trough plexi and the frame as it will need too much clearence on this big window. I had 3mm bigger holes on the small ones and the holes furthest apart cracked.
I have the green heart wood here in the caribbean and if I make a frame on the innside it could look nice and almost flush.
I think Im clooser now... Either a bolt trough at the ends to wood on the inside that also is the spacer out to the saloon panels(plexi outside) or a complete frame on the inside(plexi on the innside)

Link to illustration:
ImageShack - Image Hosting :: withframexh1.jpg

[Jmolan]

I just replaced 7 windows using a double tape and silicone attachment system. I picked up a lot of info from this thread.

http://www.cruisersforum.com/forums/...dows-4526.html

[CarlF]

As Gunner mentioned, Sikaflex has adapted the systems used for autos and office buildings to boats. "Direct bonded" glass is now used in ocean going commercial ships and CG patrol boats. It's supposed to be stronger than traditional framing and far less prone to stress fractures or problems from flex. Also, no holes to leak.

The "catch" if I understand it, is that you're supposed to put a 1" wide black ceramic stripe called a "frit" around the edge of the window to protect the sika from UV. You can see this on any car windshield. You need to have a glass company put this on for you as it is baked on. Evidently, anyone who tempers glass can also put on the frit. (I am way out of my depth here - if anyone understands this speak up)

Sika has a detailed guide on their site aimed at boat builders called "Marine Direct Glazing" that you can download.

Carl

[GordMay]

"... The adhesive selection is dependent on the type of glass used in the installation.
For all inorganic, or mineral glass, Sikaflex®-296 is the adhesive of choice.
When bonding organic glass, such as polycarbonate or acrylic, Sikaflex®-295UV is the product of choice.
Section 3 of this guide covers “Bonding Organic Glass” in great detail..."

Marine Window Bonding using Sikaflex:
http://www.sikaindustry.com/marine_d...s_aug_2004.pdf

and:
http://www.garibaldiglass.com/downlo...flex_guide.pdf

[Charlie]

I used the sikaflex system to rebed the ports on my boat. It worked really well. I encountered two problems. 1: Getting the old bedding out took forever and was unpleasant and 2) If you do not keep pressure on the window until it cures the plexiglass and sika flex may not bond together. My boat has aluminum frames that are screwed into the fiberglass. Sika Flex was also quite reasnably priced as I remember -- except for the primer. I don't know that the primer is worth husing anyway.

[flemmingsveen]

Yes I have used the Sika system on the portwindows, but for big windows Its not recomended when windows that expand and retracts with temperature. Thats my earlier problem after a while(years) when glued on the outside the capillar force gets the water in since its overlapped close to the frame. I like to get som space betwen the window and frame to prevent the capillar force to drag water in. But som boats dont have problem beacause small temperature changes.

My mind is now on to see if I can get a frame on the inside so the window will be almost flush mounted....