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Dukeofpearl 05-22-2007 02:05 PM

portlights
 
I'm rebuilding the portlights in my 1985 Crealock 37. Has anyone used plexiglass instead of laminated glass to prevent the clouding of the film inside the laminated glass recurring? You can get brass screws (5-40, 3/8, flat slot) at mcmaster.com, but has anyone used stainless? What kind of bedding material?

Thanks , Dukeofpearl

billknny 05-22-2007 02:38 PM

Duke,

I am not familiar with the exact type of portlight you have in your Crealock, but I think you will find that laminated glass gives you the best long term clarity. After all this is what automoble windows are made of, and they don't cloud up. Plexiglass and other plastic windows have a limited lifespan, as they tend to craze from long term UV exposure. A pricy alternative would be to use tempered glass.

I assume the frams of these ports are bronze, in which case you don't want to use brass screws, rather bronze would be the right choice. Stainless would work, but be sure to galvanically isolate them from the metal of the frame using Tefgel.

For many applications in portlight sealing the best sealant is the butyl windshield caulking available from auto parts dealers. It comes as a soft, somewhat sticky cord. Details would depend on the exact material and design of the port.

Bill

poopdeckpappy 05-22-2007 02:51 PM

I just went threw this, Plex vs Lexan vs Lami vs MR-10 vs tempered, ended up with tempered, the sq/in area of my ports are close to the sq/in area on your PSC and it would take a major impact to shatter the tempered and far less of an impact to crack Plex,Lex,MR-10 or lami

I installed all new gaskets, used SS screws and a clear silicon sealer, then flooded the port with a hose, out of six ports, I had one leak



I would go with the bronze fasteners, cause nothing looks cooler than a patina port

Valiente 05-22-2007 03:28 PM

I used Plexiglass to replace crazed and cloudy acrylic on my C&C design last year and used the stock "gray gasket" that most C&Cs and CSes use. But that's for Lake Ontario. Offshore, I'd go glass for opening portlights and 1/2" Lexan for hatches and fixed portlights.

JohnRPollard 05-22-2007 04:27 PM

Rebuilding the oval-style PSC portlights (supplied by Whitewater Marine) has been discussed at length on the PSC list-serve. See e.g:

Read Messages

Read Messages

Read Messages

sailingdog 05-22-2007 04:38 PM

What ever you do, don't use brass fasteners on a boat, especially on one that is on salt water.... the brass will de-zincify and then you will lose your ports. I would go with silicon bronze fasteners if the ports themselves are bronze, as you'll have the least problems with galvanic corrosion between the fasteners and the ports.

Both plexiglass (acrylic) and lexan (polycarbonate) will work for ports, but the Lexan will be far stronger. You need to make sure you get Lexan with a UV-protective coating and preferably a scratch resistant coating as well.

What you bed them with may depend on whether you go with plastic (acrylic or polycarbonate) or glass. Polysulfide-based sealants will attack lexan or plexiglass, polyureathane-based ones will not. I would bed them with 3M 4200... since it is very likely that you will have to replace them at some point in the future.

poopdeckpappy 05-22-2007 04:54 PM

Quote:

Originally Posted by sailingdog
You need to make sure you get Lexan with a UV-protective coating and preferably a scratch resistant coating as well.

This would be the MR-10 lexan me thinks, but MR-10 is still not scatch resistant, ( and expensive ) it will scatch

I think the guys @ the PSC site are confusing tempered, lami and dual glazed, lami is the only one I know that has a film, temp does not and dual is a air space sandwiched by two panes of tempered.

sailingdog 05-22-2007 05:23 PM

BTW, if you're looking for a cheap source for plexiglass or polycarbonate, it is not a bad idea to go and talk to a commercial sign supply company. That's where I got my 3/8" lexan for my new dropboards...and it was relatively cheap. :D

hellosailor 05-22-2007 05:29 PM

Pappy, MR-10 aka "Margard" is indeed scratch-resistant--but sometimes on one side only. Scratch-resistance is a relative thing, any glazing manufacturer should be able to give you comparison figures or even send out a sample piece.

What kind of tempered glass did you get that is stronger than polycarbonate? Or are you comparing inch-thick tempered glass to 1/16" thick low-grade polycarbonate?

poopdeckpappy 05-22-2007 07:54 PM

Hellosailor, comparing only 3/16th material, ( this is my frame size ) the tempered is equivalent to what you would find in a driver or passenger door window ( DOT std 615 )

my windows are small, ranging from 8x21 down to 4x17 so that added to the rating, it would take a hufty blown to break the window

But, like I said, I did the whole vs thing when I replaced them and it came down to MR-10 vs tempered and the final factor was scatches and cost, tempered was less expensive and is/will be more readily available if needed


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