Plexiglass fracturing

PDQ issues applicable across all PDQ Yachts (or if you can't find a place for something, it probably belongs here for now)
David West
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Plexiglass fracturing

Post by David West » Sat Feb 05, 2011 4:20 pm

A year ago my fixed window extending laterally from close to the mast base on my PDQ36 sprung a leak. I had a local yard remove and rebed the plexiglass. This year the plexiglass split vertically and the two pieces left a sixteeth of an inch space between them. This made me think that the cause had been a contraction disparity between the plexiglass and the structure of the boat. I immediately checked the tightness of the screws attaching the glass to the boat but they were were not tight and so I presume the problem was due to the bedding material. I can get hold of plexiglass and have it shaped locally but I am reluctant to get the local yard to do the job this time. Can anyone recommend what bedding material to use if I do the job myself or tell me if I need to search for another yard.

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Re: Plexiglass fracturing

Post by Allezcat » Sat Feb 05, 2011 10:23 pm

David,

I replaced all the fixed windows on my 36 about 6 months ago. I recommend you use Sikaflex 295UV sealant and their cleaner and primer. It is formulated for this very task and will adhere to the acrylic and the boat. The fasteners are only to hold the window in place until the sealant cures. I have no leaks in any of the windows. You need to make the screw holes slightly larger than the screws and do not use countersinking screws. Also, rubber washers should be used to provide a 1/8" gap between the window and the boat. This is so that when the window expands in the sun it does not break the seal. Sikaflex has all these instructions on their website and if you follow them carefully you will have great success.
The 36 also had a problem with the blocking under the mast. If the shrouds are tightened excessively, the mast compresses the deck under it. This can lead to cracking of the windows closest to the mast. I would remove the access panel inside the salon and check the blocking to see if it has compressed.

Hope this helps,
Chet
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Bob
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Re: Plexiglass fracturing

Post by Bob » Sun Feb 06, 2011 4:02 pm

Sandy, did you have to have the curved ones heat shaped by the supplier or can they be cold bent? Also did you use Lexan (polycarbonate) or plexiglass?
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Re: Plexiglass fracturing

Post by maxicrom » Mon Feb 07, 2011 9:49 am

David,
2 of my side windows had cracks in them, one of each side. I removed them and took them to Annapolis Maritime Plastics to use as templates. It worked out that it was less expensive to have four windows cut (possibly due to raw sheet size). Per their recommendation I went with U\V stabilized plexi-glas that was a little thicker than the originals. One note - the screw holes in our boat were not exactly the same for both ports so I did not have any of the new windows drilled. When I was ready to reinstall I marked and drilled each window at the boat. They drilled easily (drill press) and added a slight countersink for the screwheads. A couple of the screw holes were a little loose so I added wood shimming as a bandaid because the once the Siki-Flex set up that would hold the port in place. No leaks so far and one more of the old windows has a crack, so the spares are handy to have. Our boat is a 1991 so I think the cracks are due to age. Our hatches are all pretty crazed, they will be next.

Hope this helps,

Mike
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Re: Plexiglass fracturing

Post by amytom » Sat May 07, 2011 4:25 pm

I've got a leak on my port side windows. Looks like I'll be using the Sikaflex 295UV with all the pretreatments.

At $20.00 bucks a tube, how many tubes do I need to remove and re-bed the window?


Tom

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Re: Plexiglass fracturing

Post by James Power » Sat May 07, 2011 6:16 pm

Hey Tom,

I would have at least 3 or 4 tubes on hand. Better to have too many then too little, then return the unused tubes. Taping off the window and cabin side before hand will help with clean up, and West Marine sells black plastic mix sticks( # 318287 ) that are also very handy. Gloves, acitone and LOTS OF RAGS will also help out.

James

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Re: Plexiglass fracturing

Post by amytom » Sat May 07, 2011 9:18 pm

Thanks James.

David West
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Re: Plexiglass fracturing

Post by David West » Mon May 09, 2011 9:03 am

amytom wrote:I've got a leak on my port side windows. Looks like I'll be using the Sikaflex 295UV with all the pretreatments.

At $20.00 bucks a tube, how many tubes do I need to remove and re-bed the window?


Tom
Tom, having finished replacing my port front window I have confidence that I can do it again if necessary. I use only two tubes of Sikaflex. I was careful not to stick down the whole area under the window for fear of expansion causing another break and so only placed a ring of sikaflex under the outer edge of the plexiglass and another around the edge of the window cutaway. I still had to remove some excess of Sikaflex after the window was screwed down. I don't know if this was a smart way to go about it but it all seems very solid and water-tight, I guess time will tell. David.

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Re: Plexiglass fracturing

Post by amytom » Mon May 09, 2011 11:11 am

Thanks David.

Unfortunately this project (as well as many others) will have to wait now. The evil J.O.B. keeps getting in the way.

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Re: Plexiglass fracturing

Post by Exit Strategy » Wed Jun 22, 2011 4:47 pm

Hello fellow PDQ owners. This is my first email after purchasing a 1999 PDQ 36 (F/K/A Half Moon) from Mr. Alex Kehayes. A ceremonial renaming of Exit Strategy has left us now with the important "to-do" list, one of which happens to be replacing a port fixed window panels. The fore-most panel (the bent one) is cracked. Alex explained that this is at least the 3rd replacement for this window beause the 2 most recent panels cracked very soon after a marina installed them. Can anyone provide any ideas where I can get a replacement acrylic panel for this window? I have checked with the boat manufacturer, MAS precision plastics (original supplier to the builder) and an Annapolis plastics company with no luck. Thanks in advance for any assistance. Regards, Mike

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Re: Plexiglass fracturing

Post by maxicrom » Thu Jun 23, 2011 12:23 pm

Not sure where you are located - as I mentioned in the earlier post Annapolis Maritime Plastics made mine for me. I took them the old window to use a template for the new ones. I drilled my own holes because some of mine were stripped out and I relocated them. I had a couple extras made for spares and they have come in handy as once the plastic reaches certain age the elastic properties fade and you get cracks (the new ones have held up fine).
Mike & Linda
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Re: Plexiglass fracturing

Post by Exit Strategy » Thu Jun 23, 2011 5:42 pm

I live west of Cleveland, Ohio and the boat will be lying in Lake Erie for the next few years. I spoke to a person at Annapolis Maritime Plastics and he would not commit to having a mold, partly because he wasn't sure what to look for and partly because they have recently moved and threw away many old molds. I guess my best bet may be to try to find a local plastics company. If you have any further suggestions, they are appreciated. Thanks, Mike.

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Re: Plexiglass fracturing

Post by Page 83 » Sun Jun 26, 2011 11:53 am

James: you suggested not usoing screws to mount the fixed windows. Is that still a good idea? what mastic works best?
Sandy Daugherty "Page 83" PDQ 36026

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Re: Plexiglass fracturing

Post by Exit Strategy » Fri Jul 29, 2011 1:33 pm

Bob wrote:Sandy, did you have to have the curved ones heat shaped by the supplier or can they be cold bent? Also did you use Lexan (polycarbonate) or plexiglass?
Bob,
Did you ever receive an answer to this "heat shaped" question? I am having a replacement window made on the port front brow window and the manufacturer feels that it may be able to be cold formed during installation. Many thanks for your advice. Regards, Mike

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Re: Plexiglass fracturing

Post by amytom » Sat Jul 30, 2011 10:40 am

The Sikaflex is on order and I plan to do the repair next weekend.

How difficult is the removal of the windows? Should I invest in a windsheild removal tool?

Also, the clean up; I also ordered the required cleaner/primer and activator with the sikaflex but how clean do the surfaces have to be? Razor scraper for mechanical then wipe with acetone?

When shaping the sikflex, is the "wet finger" method used with caulk going to work? Of course the edges will be taped off for clean lines.

Tom

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