# Replacing windows by adhesive & Butyl tape?



## anerussis (Dec 26, 2011)

The previous owner of the C&C 26 which I recently purchased in an attempt to stop water leaks has made a mess of the windows. 
***I have purchased 1/4" dark tinted plexiglass which I cut approx 3/4" all around greater then the window frames. I am considering to just surface glue them on by using butyl tape and adhesive and possibly perhaps several screws.
Any suggestions would be appreciated.


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## mikel1 (Oct 19, 2008)

And you think they're a mess NOW! I want after pics of this job . . . . Seriously though, you best remove the mess there and start over with butyl etc. Check some of the how to stuff by compass marine (maine sail) he is the butyl expert, ton of great stuff there.


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## anerussis (Dec 26, 2011)

mikel1 said:


> And you think they're a mess NOW! I want after pics of this job . . . . Seriously though, you best remove the mess there and start over with butyl etc. Check some of the how to stuff by compass marine (maine sail) he is the butyl expert, ton of great stuff there.


I made a mistake - I did not mean Butyl tape but 3M 4991 double sided tape. I have seen several boats at marinas with surface mounted windows strictly relying on the tape adhesion. Seems a simple way of replacing windows and at the same time covering all the screw holes and other imperfections. **But perhaps not? **


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## capta (Jun 27, 2011)

Is this tape you are considering using strong enough that you are going to bet your life that it will hold those windows on in an unexpected bit of wind and seas?
I'd always heard that the Great Lakes can be treacherous?


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## chef2sail (Nov 27, 2007)

GO to C&C owners site. No way this will be an adequate solution just by doing that. This will take a fair amount of p[reparation. Once you remove the old windows you have to repair the water damage as this is a balsa cored area and I am sure that some of the core. has been permanently damaged. This work will take care and time, but can be done Actual relacement windows for all C&Cs can be ordered through SouthShore Yachts.

dave


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## anerussis (Dec 26, 2011)

chef2sail said:


> GO to C&C owners site. No way this will be an adequate solution just by doing that. This will take a fair amount of p[reparation. Once you remove the old windows you have to repair the water damage as this is a balsa cored area and I am sure that some of the core. has been permanently damaged. This work will take care and time, but can be done Actual relacement windows for all C&Cs can be ordered through SouthShore Yachts.
> 
> dave


OK - New Windows would be my first choice but I fear it would not be cost affective -followed by just replacing the plexiglass but I think the problem would be all those little screws --- have asked SSY for a quote on two main cabin windows.


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## anerussis (Dec 26, 2011)

capta said:


> Is this tape you are considering using strong enough that you are going to bet your life that it will hold those windows on in an unexpected bit of wind and seas?
> I'd always heard that the Great Lakes can be treacherous?


I appears that some new boats use this method but perhaps they don't just rely on the adhesive bond. Is there more to this then meets the eye?

Just checked the C&C owners pages and googled the subject --- and yes - just adhesive is used to secure the windows and thus eliminating the prone to water leak screws.


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## svHyLyte (Nov 13, 2008)

Some friends of ours replaced their windows using 3M VHB tape and were quite pleased with the results--for a short while. Then they began to experience separation and leakage at several locations and that, unfortunately, at sea while en route to Trinidad. 

If you are in an area with very high temperatures for long during the year, the adhesive evidently doesn't hold up. Our friends ended up having to drill the new windows to take the barrel bolts and exterior frames the original windows were fitted with to finally defeat their leakage problems.

FWIW...


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## anerussis (Dec 26, 2011)

chef2sail said:


> GO to C&C owners site. No way this will be an adequate solution just by doing that. This will take a fair amount of p[reparation. Once you remove the old windows you have to repair the water damage as this is a balsa cored area and I am sure that some of the core. has been permanently damaged. This work will take care and time, but can be done Actual relacement windows for all C&Cs can be ordered through SouthShore Yachts.
> 
> dave


OK got quote Approx $800 for only two windows which I am cut and pasting - not cost effective at all unless one has more money then brains --
Windows for a C&C 26 sell for $250.00 each. These are made from Cast Acrylic 
not the regular extruded Plexi. Cast is much stronger than extruded. The
glue to install them we recommend Plexus MA590 which sells for $125.00 per
tube (2 required) and the applicator for the glue we rent for $50.00 for a
two week rental.


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## flyingjib (Mar 5, 2012)

anerussis said:


> OK got quote Approx $800 for only two windows which I am cut and pasting - not cost effective at all unless one has more money then brains ...


Last spring I replaced windows on my C&C 30. They were all scratched up and leaking pretty bad. I had a local shop cut acrylic using my old windows as template. The shop (Maritime Plastics in Annapolis) recommended SCS2000 SilPruf. I didn't want to use any fasteners but I installed a few temporary screws and brackets to hold them in place for a few days until everything cured. The entire project ran about $400.


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## b40Ibis (Apr 27, 2011)

butyl tape is the way to go for the sealant(as previously suggested-see mainesail"s but he does not specifically address port lites, but deck hardware). The adhesive should be mechanical, i.e. screws every so often inches. 
The screws hold it all together, the butyl creates the water proof seal.
I am assuming there are existing screws/bolts or something?


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## anerussis (Dec 26, 2011)

Early this afternoon I removed one of the main cabin windows. Despite trying to be patient and very careful I managed to bend the window frame. Trying to get the old plastic out was futile. The previous owner had tried to replace the windows using thin Home depot plastic and tons of some kind of adhesive that was rock hard. 
*What I did was:*
(1) I cut 1/4" dark tinted cast acrylic approx 1" or so larger then the metal frame top and bottom and added about 6" left and right which I cut semi circular.
(2) Pre drilled 8 screw holes - one each side and 3 top - 3 bottom. 
(3)Positioned window and outlined its shape and screw holes with pencil on the boat. 
(4)Masked about 1/4" outside the line and applied a bead of adhesive and double sided automotive tape. 
(5)Carefully positioned windows using the screws as pilots and only snugged the screws. 
(6)Ran my latex gloved finger around the perimeter silicone adhesive and immediately removed the masking tape and the protective film on the windows. 
(7)Went down below and also masked the inside of the windows and applied another line of adhesive. 
**For one window from start to finish it took me approx 3 hours most of which was surface preparation, with some stressful moments when caulking. 
**The material cost was: The acrylic for both windows $67, the 3m automotive tape $19.67, the adhesive caulking ($13.49 /tube) bought 2 for $26.98, latex gloves $3.55, Alcohol cleaner $1.59. Total cost $118.79 for two main cabin windows approx 9" x 37".
Will get to the second window when I find time and weather permits.

The finished job looks better then I expected and at least in my opinion, seems to give the boat a fresher look. Now lets hope the silicone adhesive hold and window does not leak at least for the next couple of years.


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## hellosailor (Apr 11, 2006)

Screw holes?
Are you aware that th screw holes must be oversized, sometimes twice the diameter of the screws or bolts, in order to allow the plastic to expand and contract without causing it to craze?
Your screws/bolts need to have large washers (i.e barrel washers, fender washers) to allow the plastic to move under them. GE and other glazing makers having plenty of docs and drawings online showing exactly how to measure and do this properly.
Done improperly? You can guarantee the glazing will craze in time.

Silicon sealant in general also does not bond to acrylics like plexi. It sticks for a while, then pops free as the plastic thermal cycles. There are better adhesives meant for the purpose. So...somewhere in your future, there's going to be a re-do. If you want that one to last forever, read the documents that all those nice vendors have posted online. Don't guess.


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## anerussis (Dec 26, 2011)

hellosailor said:


> Screw holes?
> Are you aware that th screw holes must be oversized, sometimes twice the diameter of the screws or bolts, in order to allow the plastic to expand and contract without causing it to craze?


I am aware that the screw holes should not be too small - however twice the size as you suggest would not hold the screws. The factory did use many screws to secure the original window frame. Yes even though your advise is very valid, the bottom line is that it's just an older boat and I never planned to marry it to death do as part.


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## AirborneSF (Dec 14, 2010)

There was a article in 'Good Old Boat' about using neoprene as a gasket on 'portlights', reported to be "water tight", after years of use? There are post on CnC photo site about doing this also. I am going to go with the 'neoprene' gasket, through bolted, and hope I NEVER have to deal with leaking 'portlights' again. .02


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## NautiC25 (Feb 15, 2012)

Catalina Direct: Sealant for Plexiglas Fixed Ports & Opening Hatches


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## anerussis (Dec 26, 2011)

AirborneSF said:


> There was a article in 'Good Old Boat' about using neoprene as a gasket on 'portlights', reported to be "water tight", after years of use? There are post on CnC photo site about doing this also. I am going to go with the 'neoprene' gasket, through bolted, and hope I NEVER have to deal with leaking 'portlights' again. .02


Yes I agree but I couldn't find this neoprene gasket - When I inquired at my local marine supply they sold me Butyl tape which after doing some research I didn't use. I did use a 3M automotive tape and also Dow 795. 
ALSO of interest is - the previous owner had replaced the acrylic on the original windows which did leak badly. When I removed them I noticed that there was tons of silicone between the windows and the frames but little if any between the metal frame and the boats fiberglass which was obviously the source of leaks. Plan to clean the frames and in the future if my present windows start leaking will properly re-install these frames with new acrylic.


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## hellosailor (Apr 11, 2006)

"however twice the size as you suggest would not hold the screws."
That's correct, which is why WASHERS or large diameter screw heads may be required. The size of the hole has to be made to accomodate the expansion in the sheet ofplexi. If that is 1/16" per foot and you have a three foot long sheet, you may need 3/16" of free space--even if your screw's body is only 1/8". The size of the head may or may not cover that. Basing the size of the hole on what size screw heads were randomly available, is setting the cart before the horse.
But as you say, you're not going to marry the boat, so if the windows are leaky when you go to sell it, or the next buyer sees a job not done right...all it affects is price.

WRT neoprene gasket, be aware that there is "chemically blown" foamed neoprene, and "gas blown" foamed neoprene. The gas blown type is "fizzed" with inert gas to form the foam. The chemically blown type is made like a pancake batter, chemical reactions make it foam up, and if anyone has cheated on the chemicals, it may turn to goo or powder down the line. Sometimes five years, sometimes twenty. So caveat emptor, you can guess which is more expensive.

So a quick simple fix, I'd just use 3M's VBT(?) tape, the structural double-sided tape that is used to secure windows in skyscrapers. Apparently works very nicely on boat glazing as well, and doesn't require holes or hardware.


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## DonScribner (Jan 9, 2011)

a) Use VHB tape but check what it is compatible with. Another option is structural glazing tape. (Tremco SGT or equal) 
b) Install it approximately 1/4" in from the edge of the glazing. Be VERY careful because once it contacts it's over (for the most part anyway). 
c) Once applied to the cabin, roll HARD around the entire edge until you get tired, then do it again. 
d) Mask with blue painters tape 2" around the perimeter. 
e) Stuff a pencil thru something round and rubber that will position the point 1/4-5/16 from the perimeter of the rubber. A small tire from a toy car works well. Roll this around the perimeter of your glazing, making a perfect offset. 
f) Carefully cut on this mark with a sharp razor and remove the tape nearest the glazing. 
g) Tape the edge of the glazing overhanging the tape slightly then trim excess off with the razor. 
h) Inject structural silicone into the crack under the glazing and apply a liberal bead all around the perimeter. 
i) TOOL the silicone, a plastic spoon works well. Don't listen to those that claim they're so good, they never tool their sealant. I'm a glazing designer. Sealant isn't waterproof or warrantied unless it's tooled properly. 
j) Remove the tape almost immediately, being careful not to goop anything up. When cured your portlight will be virtually immovable. This is the same basic joint that keeps the windows in many modern high-rise buildings.

If you're careful, the bead will be as consistent and attractive as a rubber gasket and you may be able to get a color match to your cabin or plain ol' black.

This installation is the bomb for a recreational cruiser. It'll keep you safe and dry for years. If you're crossing an ocean . . . let a professional fix it.


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## anerussis (Dec 26, 2011)

Where were all you good people with the advise before I started my re-seal job? I googled and visited two marine supply houses but didn't find or get advise anywhere near as good as I now get. 

Anyways I think the job I did is not perfect but it seems OK and from a distance looks great. I am actually proud of my even perimeter caulking job BUT I am disappointed that close-up and when the sun hits the windows I can see my not so straight and un-even silicone and tape lines through the dark tinted plexi. --- 
Also I just learned that tooling the silicone is required in order for it to do it's job. Unfortunately all I did was apply two lines of Dow 795 on the fiberglass one - approx 1/4 to 3/8 in from the outlined perimeter of where the plexi would go and another bead around the window opening and then just pressed the plexi in place and secured it in place with 8 screws. The silicone that squished out I then smoothed with the latex glove wet finger method.
Oh well live and learn - at least now I can help others do a proper job.


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## gstewart8 (Nov 3, 2011)

DonScribner said:


> a) Use VHB tape but check what it is compatible with. Another option is structural glazing tape. (Tremco SGT or equal)
> b) Install it approximately 1/4" in from the edge of the glazing. Be VERY careful because once it contacts it's over (for the most part anyway).
> c) Once applied to the cabin, roll HARD around the entire edge until you get tired, then do it again.
> d) Mask with blue painters tape 2" around the perimeter.
> ...


This is very helpful. I have a few questions that you or others might be able to answer.
I want to cover three openings with a single strip of Plexiglas that will be 68" long and 10" high. The surface has a curve so the Plexiglas needs to be flexible.
What thickness would you recommend for the glass?
Will Plexiglas take the curve or might I be better to use Lexan?
Will the tape be sufficient to hold the glass with a curve or would I need to use a few screws to achieve and hold the bend?
Thanks


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## tschmidty (Sep 25, 2008)

For the silicon edges, I have seen someones example of painting the back side of the plexiglass with a black paint, which naturally means you are dependent on the bond of the paint itself to the plexiglass. The recommendation was to use automotive exhaust pain.

See this thread http://www.sailnet.com/forums/gear-maintenance/129994-lexan-polycarbonate-vs-acrylic.html

For a window 68" long I'd definitely be concerned with expansion. The tape would probably hold but you'd need to secure it first with screws most likely. The idea of screws with either large heads or washers underneath is a good one as well.


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## DonScribner (Jan 9, 2011)

VHB and silicone will take hand this much expansion with no problem. You're looking at about 3/16" per 100 degrees lengthwise. The fiberglass will expand also, but not at the same rate. It can't be too different though, otherwise all those boats with screwed on plexi portlights would have exploded long ago.


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## Multihullgirl (Dec 2, 2010)

You don't paint the back side (adhesion side) of the plex. The outside is painted. Mine came from the factory that way, so I just redid the same


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## tschmidty (Sep 25, 2008)

> If the color of your plastic is not dark enough to hide the grey tape (and sealant), you may want to paint the inside perimeter of the pane. This will also protect the adhesives from potential UV attack, but the bond strength will depend on the paint adhesion. According to some professionals, silicone-based, high-temperature exhaust paint is both compatible and tenacious. The area to be painted is the area exposed when you remove the ring of film.


From this article, your beliefs may vary.

Replacing Fixed Portlights | Sail Magazine

And this is the paint recommended.

Amazon.com: DEI 010301 Black High-Temperature Silicone Coating: [email protected]@[email protected]@http://ecx.images-amazon.com/images/I/41D5SWESl%[email protected]@[email protected]@41D5SWESl%2BL


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## SailRedemption (Jun 29, 2013)

gstewart8 said:


> This is very helpful. I have a few questions that you or others might be able to answer.
> I want to cover three openings with a single strip of Plexiglas that will be 68" long and 10" high. The surface has a curve so the Plexiglas needs to be flexible.
> What thickness would you recommend for the glass?
> Will Plexiglas take the curve or might I be better to use Lexan?
> ...


My windows were about your length and height, I used 1/2" plexiglass. I mounted them with the protective paper still on, got a new razor knife and cut a line from the inside where the actual molding is. Before taking off tape the exterior around the window for easy cleanup of adhesive. Took them off, peeled the outside paper off on the inside of the glass leaving the ovals/shapes where you would see out of. Tape the outer edge, then spray painted the inside of the glass with basic flat black enamel. This keeps you from seeing your adhesive bead marks from outside. Then had my window exterior prepped and stuck them with DOW 595 very liberally and screwed them on.

I unfortunately didn't take any pictures. If you have anymore questions, shoot.


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## Vasco (Sep 24, 2006)

Just replaced the windows on my CS36Merlin. This is what I got.
Fix Leaky Boat Window Kits
The aluminum frames are through bolted. No matter what you do, without the frames the window will eventually separate a bit and start leaking.


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## svHyLyte (Nov 13, 2008)

Vasco said:


> Just replaced the windows on my CS36Merlin. This is what I got.
> Fix Leaky Boat Window Kits
> The aluminum frames are through bolted. No matter what you do, without the frames the window will eventually separate a bit and start leaking.


Correct. Friends of ours replaced their fixed ports using 3M's "strongest" VHB that the 3M tech service assured them was all that was needed. Weather tightness lasted about 6 months but leaking began on their trip between the Bahamas and the DR. By the time they made it to the BVI a week or two later, the only thing keeping water out was a layer of duct-tape around the entire edge of the windows. They subsequently went through terrific brain damage drilling 94 bolt-holes through the plastic to reinstall the bolts for the frames they supposedly wouldn't need in view of the VHB. Fortunately, they had kept the frames, "just in case".

FWIW...


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## single2coil (Apr 12, 2014)

I own a C&C 34. just finished replacing the windows (4) / side portlights. Sail mag has the best process for replacing the windows. It is all about CTE. Coefficient of thermal expansion. No point in the fasteners as the article will explain. But using VHB double tape and Dow Corning caulk has worked very well. 98% is in prep: As in any fix.
sailmagazine.com/boatworks/replacing-fixed-portlights]Replacing Fixed Portlights | Sail Magazine


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