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23-05-2011, 04:41
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#1
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Registered User
Join Date: Dec 2010
Location: Bradenton, Fl.
Boat: Marlow 42SS
Posts: 34
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Replacing Smoked Plastic Window
Greetings!
I am in the process of replacing my cracked plastic windows. I have found a company to make them (about$100 a pop) and I have taken one out to be used as a template. Where I need advice is the black (I believe it to be 3M 5200) sealant and getting the old surface clean for the new window. I have putty knifed off as much as I can but it is still a mess. I thought about a wire wheel but think that would probably be too abrasive and take off some fiberglass with it so I hope some one out there has done this and can shed some light on this for me.
Thanks in advance.
Don
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23-05-2011, 04:50
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#2
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C.L.O.D
Join Date: Apr 2010
Posts: 8,232
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Re: Replacing Smoked plastic window advice
Why bother with plastic? We replaced ours with tempered glass... although a little heavier, it's stronger, looks better and lasts longer...
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23-05-2011, 05:24
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#3
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Registered User
Join Date: Feb 2010
Location: Durban South Africa
Boat: L 34
Posts: 284
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Re: Replacing Smoked plastic window advice
The sealant is Sikaflex 295UV. Scrape as much as you can, Clean well with acetone or laquer thinners, if the coachroof does not have too much of a curve you can stick the new acrylic down with a narrow strip of double-sided tape,use one at least 3mm thick, so you can inject your new sealant into the gap. If there are screws, remember that the holes should be drilled oversize as the screws are only there to hold the acrylic in place while the sealant goes off.A tight hole for the screws will result in cracked acrylic due to expansion.I recommend the tape on the inner circumferance and the goop on the outer. Mask the boat and acrylic well to help with final cleanup.
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23-05-2011, 05:43
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#4
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Moderator
Join Date: Aug 2009
Location: Solent, England
Boat: Moody 31
Posts: 18,429
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Re: Replacing Smoked plastic window advice
How good are you with hand tools. I used a bare stanley knife blade to remove glue left behind when I removed a sticky vinyl stripe on our cabin top. You have to be careful not to nick the GRP but if the angle is right a new sharp blade will shave layers off.
Pete
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23-05-2011, 06:48
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#5
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Registered User
Join Date: Dec 2007
Boat: Mahe 36, Helia 44 Evo, MY 37
Posts: 5,731
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Re: Replacing Smoked plastic window advice
3DPhoto,
The adhesive is standard automotive window glass adhesive with one difference.
Most Marine windows are not glass, so a primer has to be used on just the plastic window so the adhesive will bond.
Dow Automotive BETAMATE7120 Single-component, high-viscosity, atmospheric humidity-curing polyurethane bonding/sealing compound for high-strength, permanently elastic adhesive joints. Apply ½ thick and squeezed out to 3/8 when window is installed
Dow Automotive Betaprime 5404 Pinchweld and encapsulation Primer. Used only on the plastic window sheet. Lightly scotbright 2” around bounding edge and apply this primer onto the sanded 2” area around the outer edge
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23-05-2011, 07:33
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#6
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Resin Head
Join Date: Aug 2007
Location: Seattle WA
Boat: Nauticat
Posts: 7,205
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Re: Replacing Smoked plastic window advice
A nice sharp chisel used in reverse is usually my choice. A rubber mallet can help with control on corners, etc. If you hit it with a heat gun as you scrape sometimes that will help by softening the goop too. Have fun!
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23-05-2011, 08:11
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#7
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Registered User
Join Date: May 2011
Location: Miami Florida
Boat: Ellis Flybridge 28
Posts: 4,057
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Re: Replacing Smoked plastic window advice
There are a few solvents on the market that will help with removing 5200 and other adhesive sealants. BoatLife makes one: BoatLIFE | Release Adhesive & Sealant Remover 1oz. - Solvents & Removers
Anti-Bond is another one.
__________________
Retired from Hopkins-Carter Marine Supplies
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23-05-2011, 17:30
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#8
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Registered User
Join Date: Dec 2010
Location: Bradenton, Fl.
Boat: Marlow 42SS
Posts: 34
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Re: Replacing Smoked plastic window advice
Thanks to all for the good advice. Of course the guy at the plastics factory said that I could just use clear silicone, I tried to hide my cringe, as previous owner thought you could use clear silicone EVERYWHERE and did...
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23-05-2011, 17:51
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#9
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Registered User
Join Date: Mar 2007
Location: Santa Cruz
Boat: SAnta Cruz 27
Posts: 6,711
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Re: Replacing Smoked plastic window advice
If the PO had used silicone, you would be done with the prep by now. There are some great glazing silicones.
PS, if the windows have holes drilled in them, take them both out to use as patterns--don't trust them to be identical.
Also, don't wipe the new plastic off with hydrocarbon based solvents. It will craze within a year or two.
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23-05-2011, 18:11
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#10
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Registered User
Join Date: Aug 2006
Location: Brisbane Australia [until the boats launched]
Boat: 50ft powercat, light,long and low powered
Posts: 4,409
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Re: Replacing Smoked plastic window advice
Quote:
Originally Posted by 3DPhoto
Thanks to all for the good advice. Of course the guy at the plastics factory said that I could just use clear silicone,.
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Well it does have the runs on the board
I have seen crazed windows taken off of cored cabin boats that had windows stuck in with roof and guttering silicone.
The paint and fiberglass was torn off before the silicone let go.
Saying that, I used double sided tape from 3m and black butyl mastic to back fill, as used in the auto industry for years
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23-05-2011, 18:45
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#11
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Registered User
Join Date: Sep 2009
Location: New Bern NC
Boat: Searunner 34 Trimaran
Posts: 1,660
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Re: Replacing Smoked plastic window advice
I installed my 8 TOUGH Lexan ports as well as glazed the dodger and my hatches with the the "nuts N bolts method", using silicone caulk. They have been pounded hard and remain leak free now, 16 years later.
I had called GE who makes the Lexan for their advice. Plastics have a coefficient of expansion that is many times that of the boat, so the attachment is best done in a mechanical way with a VERY resilient caulk, but also in a way that allows them to "float"... (Move around) I accomplished this by using barrel nuts in the cabin sides, and on the holes through the plastic, I used perfectly centered, SS, truss head, machine screws... that were HALF the size of the hole that they went through. Adhesion was not as important as resilientcy!
GE recommended "SILPRUF" silicone caulk, that they alone sell. It is available by ordering from them, and only by the case. It comes in colors, so on the dark tint, I used a dark caulk, on the white dodger, I used white. What is so incredibly different about this caulk, is that it gives about 40 minutes of working time, VS only 5! When doing a long installation, this means a lot! I would never install my plastic with anything else.
Mark
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23-05-2011, 19:10
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#12
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Resin Head
Join Date: Aug 2007
Location: Seattle WA
Boat: Nauticat
Posts: 7,205
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Re: Replacing Smoked plastic window advice
One reason I dislike silicone sealants is that if you sand up to a bead of silicone and hit the silicone with your grit, you will never get rid of the microscopic particles of silicone on your boat. It will cause serious problems with fish-eyes in both varnish and paint. We've seen it happen in the yard many times over the years. Often people cant figure out why they are having such a problem with fish-eyes in their finish, and I've seen them blame it on everything from smog to the boat next doors buffer sling. Usually its the little bead of clear silicone sealant someone barely even noticed while sanding. Worst contaminant ever, once it's there you just cant get rid of it. I'd never use anything silicone based on my boat as a result. But then I've got lots of teak to keep varnished, I'm sure it's not a problem for some...
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23-05-2011, 19:43
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#13
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Registered User
Join Date: Sep 2009
Location: New Bern NC
Boat: Searunner 34 Trimaran
Posts: 1,660
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Re: Replacing Smoked plastic window advice
Quote:
Originally Posted by minaret
One reason I dislike silicone sealants is that if you sand up to a bead of silicone and hit the silicone with your grit, you will never get rid of the microscopic particles of silicone on your boat. It will cause serious problems with fish-eyes in both varnish and paint. We've seen it happen in the yard many times over the years. Often people cant figure out why they are having such a problem with fish-eyes in their finish, and I've seen them blame it on everything from smog to the boat next doors buffer sling. Usually its the little bead of clear silicone sealant someone barely even noticed while sanding. Worst contaminant ever, once it's there you just cant get rid of it. I'd never use anything silicone based on my boat as a result. But then I've got lots of teak to keep varnished, I'm sure it's not a problem for some...
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Valid point, but the answer is to remove the silicone residue. I have painted our boat with AwlGrip on one occasion, and Sterling on the other. Both are two part LP paints, and mistakes are EXPENSIVE! I have also spent years in boatyards and witnessed hundreds of other contractors work. The key is to assume that the hull is contaminated with McLube, wax, oil, bird turds, and silicone caulk. While the others can be solvent washed, the silicone caulk that gets "into" a slightly porous substrate, is not so deep that a simple sanding before painting will not take care of it. This is what you were going to do anyway, right? If so, no problem. Mine hasn't been...
I do agree, however, that Silicone is to be avoided on hardware and other things where it is not needed, and that in the vicinity of where you have used it, paint prep must be very thorough.
Mark
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23-05-2011, 21:42
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#14
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Registered User
Join Date: May 2011
Location: Miami Florida
Boat: Ellis Flybridge 28
Posts: 4,057
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Re: Replacing Smoked plastic window advice
My favorite sealant for plastics is LifeSeal made by BoatLife. It's flexible like silicone but adheres like polyurathane. I think it's paintable but it doesn't say so on the website. Here is the description:
A unique combination of marine silicone and polyurethane, formulated especially for fiberglass. LifeSeal® offers a fast-curing, low odor, high adhesion, non-sagging, non corrosive, non-yellowing formula. It provides a durable permanent watertight seal for joints subject to structural movement. May be used above and below the waterline. Use for sealing decks to hulls, thru-hull fittings, vinyl ports, sealing/glazing windshields and bedding marine hardware. Will adhere to metal, glass, wood, Lexan®, ABS® and certain other materials. Can be removed without damaging gel-coat. Not recommended for ferro cement hulls, impregnated wood or oil soaked materials. Cures in presence of water. Mildew resistant and acid free.
__________________
Retired from Hopkins-Carter Marine Supplies
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23-05-2011, 22:08
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#15
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Registered User
Join Date: May 2009
Location: Punta De Mita
Boat: Vagabond 39 Hull # 1
Posts: 1,842
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Re: Replacing Smoked plastic window advice
Is the original black sealant hard or is it sticky? Butyl tape stays sticky, urethane is hard. Wax, grease, and silicone remover does a great job on butyl tape after you remove most of it with a razor blade. If it's urethane you don't need to remove it all, you can trim it down with a razor blade ( a nice sharp new one) nice & smooth and squeeze a bead of new urethane right on the thin remnant of the old bead. If it's flexible but not sticky it is silicone. If it's silicone you need to remove it all. You can slide a razor blade along on top of the fiberglass and get most of it off and then scrape the rest off with the razor blade perpendicular to the surface and use acetone.
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