# Window gasket sealant..



## groundhog (Jun 27, 2006)

Speaking of leaks,

I have a window that has what looks like the same type of black rubber gasket as found in automotive windshield applications.

The black gasket was originally a straight piece and they fitted it in the oblong opening for the window.

So that means there is a cut where the gasket start/stopping point is. That is where I noticed a small leak.

Any suggestions of some magic goop type stuff?

Thanks,
gh


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## camaraderie (May 22, 2002)

Try a little back silicone.


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## Faster (Sep 13, 2005)

We've had excellent results with *Dow Corning 795* silicone. A local boat builder/repair expert recommended it to bed our plexi windows, and it has been leak free since installation, with no separation developing.

A friend with windows similar to yours removed the old gasketing material altogether and filled the frame space with the above silicone, cut some spacers from the old gasket to locate the pane in the frame, the reinstalled the frames and has had no leaks since. Mask off the frame and the lens prior to re-assembling things

It's not easy to find, not usually in the Home Depot section, but look for a wholesaler or a HVAC/plumbing/insulator supplier.


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## groundhog (Jun 27, 2006)

I did some internet searching and couldn't find a source for the Dow Corning 795.

But I did find some similar product at Ace Hardware.
Permatex® Flowable Silicone Windshield & Glass Sealant $4.95

Thanks for your input,
gh


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## carlosthedog (Sep 8, 2006)

I've used GE silicone available at Home Depot for my swimming pool. But for small jobs I use silicone for aquariums purchased at just about any hardware store. It comes in a small tube for about $3.


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## Faster (Sep 13, 2005)

GHI found a local distributor for DC 795 using this link. Maybe it will work for you.Cheershttp://www.dowcorning.com/applications/search/products/default.aspx?searchtype=dist


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## RichardElliott (Sep 24, 2001)

*Window Sealant*

Practical Sailor recently rated Ace Hardware Special Caulk (Silicone) a best buy.


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## hellosailor (Apr 11, 2006)

Groundhog, last time I head auto glass was bedded and sealed with urethane compounds, so a urethane adhesive would be the matching product for it. Any auto glass supply (or shop) should be able to sell you a tube. 

I wouldn't expect a silicone product to bond to urethane as effectively.


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## Bill Mc (Apr 10, 2006)

*Waterproof Window Caulk*

I have had the occasion to replace the portlights and skylights on my Hunter Legend. The Product that I used was called Boatlife Caulk. I removed the skylights using a piece of music wire thru the joint held with a vicegrips on each side my Firstmate and I used a sawing action to remove the skylight. After cleaning the surface and washing the area with alcohol I taped off the area around both sides of the window seam, applied the caulk, inserted the window and after about 20 minutes removed the tape. This product is said to even work underwater. However it is expensive. $10.00 USD for a small tube and about $18.00 for the size that fits in a caulk gun. It comes in clear,white and black.
Now when I put her over and the rail is in the water we have no water intrusion.

Fair Winds,

Bill
S/V Tumbleweed


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## alanl (Mar 13, 2006)

Maybe I'm new-fashioned, but I would not let silicone anywhere near a boat of mine. Polyurethane conversely, comes in different grades for use as a bonding agent and/or sealant and if properly applied on a clean, dry substrate, will outlast silicone by a factor of 10 and with none of the disadvantages. I can't comment on US availability, but the brands available here are primarily SIKAFLEX (A Swiss brand) Selleys and I'm sure 3M and Dow have them too. They are commonly used in the building, automotive and even aircraft industries. Try an Internet search

Cheers

Alan


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## hutch5151 (Jul 16, 2000)

Dow Corning 795 or GE SSG4000 (both professional glaziers sealants) are the recommended sealants. Excellent article in DIY last year on this subject. Whatever you do, don't use a polysulfide sealant on the window if it is acyrilic. The solvent crazes the acyrilic.


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## TSOJOURNER (Dec 16, 1999)

The combination of Sikaflex 291 primer and 295 sealant is the best I know of on the market for rebedding portlights. The combo is slightly expensive but well worth it if it spares all the headaches of a project that leaks.


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## yotphix (Aug 18, 2006)

I can't count the number of times that I have pulled apart leaky things and found beads of silicone stuck to only one side. When you consider that in a bathtub tile job it only lasts about 2 years before it begins to degrade and leak I can't imagine why anyone would use it on a boat in a place meant to keep out water.


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## TSOJOURNER (Dec 16, 1999)

Here is yet another product to consider:

3M 4000 UV Polyether Adhesive Sealant if your windows are plastic. (I used 5200, a polyurethane to rebed my portholes because they are Brass). You should not use a polyurethane to bond plastic because it will destroy acrylic.

This is an excellent product for rebedding windows and will give you a long lasting seal. 

I would also weigh in and agree that Silicone is a temporary fix. Let me give you an example. I recently had a "waterproofing expert" from Florida examine our waterproofing applications on a building I am completing in Maryland. He suggested that 20 year Silicone will last a maximum of of 10 years when properly applied. (Significantly less with direct exposure to weather). Imagine how long it would last in a marine environment.


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## sailingdog (Mar 19, 2006)

Surfesq-

I hope your ports are bronze not brass. Brass de-zincifies rather quickly in a saltwater environment and leaves a pretty porous and weak copper sponge behind.

I'd second the 3M 4000 sealant. Silicone is a pretty useless material for much of what is needed on a sailboat, and should really be limited in its use. Regardless of what brand silicone you use, *do not use any that smell like vinegar when they cure on a sailboat.*


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## TheBlackPearl (Sep 18, 2006)

Every single window in my '80 Hunter 37 had HORRIBLE seals. You could tell they we're original and had never been replaced, as you had to crank the knobs down so tight that several had stripped out. I contacted the manufacturer and wasn't happy at the price they quoted for replacement gaskets. One day on a trip through Lowes, I happened by the weatherstripping section and low and behold, they have every kind of weatherstripping that i needed!! I think i payed (ballpark) $40 to re-seal 15 hatches. They are absolutely wonderful now, and you don't even have to turn the knobs one turn, just flip them up and you're in waterproof nirvana!


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## jimthom (Oct 22, 2004)

*Butyl*

Another sealant/adhesive that is used for auto windscreen are the butyl-based products. Does anybody have any experience using them in a marine environment? Cheers, Jim


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## hellosailor (Apr 11, 2006)

Jim, I don't think it is the sealant itself that really matters. Automobile windshields are "floated" on a bed of sealant, so the glass is free to move and expand without ever contacting a hard surrounding. When the bond is fresh, you can literally blow the glass out of the frame by slamming a door closed.

In a boat, you need more positive retention than that (even after the bond is formed<G>) since the boat can go "poof" as it falls off a wave and the hull flexes. And, most glazing on boats is (from what I've seen) set improperly considering that the makers of the glazing say you MUST allow for expansion and contraction--you can't just bolt it down, or glue it tight into a frame.

But if you sandwich the glazing between an inner and outer frame, and place gaskets on the front and rear of the glazing (material almost insignificant as long as it can seal and flex) AND allow the expansion room around it, almost anything should work. Of course, using an inner and outer frame that way means you can't make pretty flush "Euro" portlights.<G>

There's always a tradeoff between how much quality you want/need, what it is going to cost, and what the market is willing to pay for. Betcha the ports on a battleship don't leak like the ones on a sailboat.<G>


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## sailingdog (Mar 19, 2006)

Betcha most sailboats can't take the weight of the ports off of a battleship either...


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## STARWINDY (Apr 20, 2007)

Great advice, as I'm rebedding some ports this weekend. One question though is, what is the best "removing agent" to get rid of the old seals?

The fixed lights or deadlights, were ruined when I pulled them. Too expensive to replace this season, so I'm going to cut out some temporary ones out of Lexan...use 3M 4000 to seal them and hope for a 2 year fix.

Will that work ok?


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## hellosailor (Apr 11, 2006)

"what is the best "removing agent" to get rid of the old seals?"
Usually elbow grease applied liberally with wire wheels and cabinet scrapers. There is a "5200 remover" solvent that can help but other most conventional solvents that are strong enough to get rid of sealant can also damage fiberglass, be warned.

Lexan is about 10x more expensive than acrylic, I can't see wasting it on temporary repairs. And, considering the damage that water leaks can cause, and the amount of time and labor necessary to install temporary deadlights and then UNinstall them again for the real repairs...I can't see any way that you come out ahead by not doing the real repairs the first time around. I know, we all have limited budgets, but sometimes it just pays to do it right the first time around. Faster and cheaper.


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## STARWINDY (Apr 20, 2007)

---Hello Sailor--

The reason I'm not doing the real repair is because when i pulled the leaky deadlights, the frames and glass fell to pcs. I shopped on line and looks like to replace them, I'm looking at 125.00 to 150.00 each!! 500. dollars for 4 deadlights is crazy!!

I now have 4 holes in my otherwise beautiful boat, I plan on cutting the Lexan larger than the holes and fastening them as water tight as possible. The Lexan, even the nice smoked kind...looks like about 50.00 to 75.00 for a sheet large enough to cut out the shapes i need.

I just can't sink 500 bucks into deadlights....or maybe I'm not looking on the right websites for pricing.


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## Freesail99 (Feb 13, 2006)

STARWINDY said:


> ---Hello Sailor--
> 
> The reason I'm not doing the real repair is because when i pulled the leaky deadlights, the frames and glass fell to pcs. I shopped on line and looks like to replace them, I'm looking at 125.00 to 150.00 each!! 500. dollars for 4 deadlights is crazy!!
> 
> ...


How are you planning on "framing" your Lexan ?

There was a sale on opening ports about a month ago, but they are now sold out.


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## DeepFrz (May 9, 2006)

I haven't read the whole thread so you may have already checked the thread on the Cruiser's Forum, "How to have Sexy Windows".


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## hellosailor (Apr 11, 2006)

Starwindy-
I have no idea what kind of boat you have or what kind of deadlights. It certainly isn't impossible to do, but I'm thinking anything that seals well (and ignoring the costs of sealants and fittings too) isn't going to be simple or easy, or will involve more holes to drill and seal and fill. Lots of work and time and materials and sealant to dig out/off when you finally do replace them, versus shopping around for some kind of replacements and just biting the bullet. Between a half sheet of 1/8" Lexan and everything else, you'll be sinking probably $125 in this job, that's already a quarter of the cost of just "doing it right". (I know, sometimes we all have to just make do.)
How big are the deadlights? Are they a standard shape?


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## sailingdog (Mar 19, 2006)

STARWINDY said:


> ---Hello Sailor--
> 
> The reason I'm not doing the real repair is because when i pulled the leaky deadlights, the frames and glass fell to pcs. I shopped on line and looks like to replace them, I'm looking at 125.00 to 150.00 each!! 500. dollars for 4 deadlights is crazy!!
> 
> ...


What thickness of Lexan are you getting for the ports at that price. I can't see you getting anything that I would consider seaworthy at that price, unless the ports are a lot smaller than I am thinking they are. I got a 2' x4' piece of 3/8" Lexan and it was well over $100.


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## STARWINDY (Apr 20, 2007)

*Lexan thickness and frames.*

The boat in question is a Starwind 22.

I can't seem to be able to upload a pic at the moment. If you ggole, you will quickly find one. As far as the thickness for the Lexan, I'm looking at 3/8 and the dimensions are roughly 20 1/4 by 3 3/4 inches. Two are rectangular and the other two have a slight angle sloping forward on a 45.

As far as framing them, I have no idea. I'm just going to cut the new Lexan to the same dimensions as the original + frames. The frames busted into pcs. I plan on Drilling holes into the Lexan that match up with the holes that were through the frames, establish a decent seal and put back the ss hardware. I may have to caulk around the edges of the outside of the lexan.

SailingDog.... what did you use to cut the Lexan.... i'm thinking of tile/wet saw.


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## TSOJOURNER (Dec 16, 1999)

I followed steps from the Catalina 30 site. Not sure if your windows are of the same design. Regardless, you might find some useful information here. Leaking Windows


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## sailingdog (Mar 19, 2006)

Starwindy-

A sabre saw works just fine...as does a skilsaw...  

I don't think you need frames... the deadports on a lot of new boats are essentially just sheets of lexan cut to size and then bolted over the holes in the cabin top. Drill the holes a bit oversized as the lexan expands and contracts a bit compared to the underlying boat... and if you drill the holes exactly the size you need, you can cause problems for yourself later on.


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## STARWINDY (Apr 20, 2007)

Thanks...great article.


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## hellosailor (Apr 11, 2006)

For too much information about Lexan glazing see

http://www.championindustrialplastics.com/pdf/polycarb.pdf

Somewhere abround p.18 it gets into how much allowance you need to provide for expansion/contraction, and installation illustrations. If you are just going to throughbolt it, the preferred kludge is to allow about 1/16" of space around each screw/bolt (i.e. a 1/8" wide bolt in a 1/4" wide hole) with washer, so that the plastic can expand/contract without pushing against the bolt, which would either craze the plastic or loosen the bolt.

There's also apparently a "VHB tape" from 3M which is a double-sided structural tape designed for "sticking" glazing right to a smooth surface and sealing it in one shot--not cheap and not available at your local WalMart.<G>


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## STARWINDY (Apr 20, 2007)

sailingdog said:


> Starwindy-
> 
> A sabre saw works just fine...as does a skilsaw...
> 
> I don't think you need frames... the deadports on a lot of new boats are essentially just sheets of lexan cut to size and then bolted over the holes in the cabin top. Drill the holes a bit oversized as the lexan expands and contracts a bit compared to the underlying boat... and if you drill the holes exactly the size you need, you can cause problems for yourself later on.


Thanks SAilingDOg. As usual, you leave me with a breath of confidence!!


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## sailingdog (Mar 19, 2006)

STARWINDY said:


> Thanks SAilingDOg. As usual, you leave me with a breath of confidence!!


Obviously the fumes from the sealants are getting to him...  You're welcome...


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## dvpamenter (Mar 3, 2000)

May have missed pieces of the discussion, but acrylic (plexiglas) is much cheaper, does not scratch as easily as lexan, is less likely to shatter upon hard impact (flexes a bit) and is easier to work with if fine tune shaping is needed.
Also as Sailingdog says, definitely slightly oversize the fastener holes to allow temp related movement and avoid stress cracking.
Don


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## sailingdog (Mar 19, 2006)

DVpamenter-

Acrylic is also far weaker than Polycarbonate, in both impact resistance and in terms of tensile strength. There is a reason that Lexan, not Plexiglass is used in riot shields.


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## JeffConwell (Jul 15, 2002)

*Port Sealants*

I have used 3m Strip Calk that I got at the local automotive store when replacing my old ports with new New FOund Metal Ports. They have been on for about 3 year now, and whenever I find any indication of any leaking I just tighten the screws holding the port in and a little more oozes out and the leak is fixed. You simply cut off the excess with a knife and clean it up with acetone. The stuff never gets completely hard and stays flexible so it will movwe with the boat as it sails. It is like having your own rubber custom gasket on the ports.


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## MalcolmChaddock (Mar 17, 2005)

*Butyl Tape*

I used butyl tape that I bought at Home Depot. It is called glazing tape, it comes on a 3/8" x 50' rolefor less than $10, and is used for installing windows in metal frames. I applied it to the windows on my Ranger 29. I did that about 5 years ago and have had no leaks. I used it on the recommendation of a fellow with a Catalina 25 who said his windows had been installed using butyl tape at the factory 25 years before and had never leaked. He had removed the windows to clean the frames, not to fix leaks. He said the butyl tape was still pliable and sticky, and while it is not an adhesive - the window need to be held in place with fasteners - it seemed to last indefinitely.

I had tried a polyurethane sealant before and it last only a couple of years. 
One of the benefits of butyl tape is that it stays pliable and sticky, which is also a drawback. if you use a full-width strip, about 3/8", it is really too much sealant, and will continue to squish out around the frame. it is easy enough to clean off, but just one more thing to do occasionally. 
The best way to avoid using too much is to roll it like modeling clay to a rope of about 3/16", then stick the rope in place on the mating surface of the window frame. Tighten the screws a bit all around the frame, going a half a turn of each screw until it is flush with the cabin surface. 
Good stuff, and cheap!


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## hellosailor (Apr 11, 2006)

IIRC The old C&C hull to deck joints were "caulked" with black butyl tape for the same reason. As long as no one went gorilla and squeezed it all out, they would stay pliable and seal well for years and years, just a little tightening needed if they didn't quite.

And Home Depot's been HIDING IT FROM ME? <G>


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## mandolinwind (Aug 22, 2006)

sika flex is definately the best - different grades per Oz above but great stuff.
Having been in the marine industry as a mechanic, this is the one to rely on.
Silicone had a short life span.
Cheers,


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## windhamagic (Jul 11, 2014)

Select Plastics in Norwalk CT has the best product for rebedding plastic ports call them (203-866-5284), they might try to sell you new plastic but just order the adhesive. Do not ever use anything else it will always end up leaking.


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