Preparing surface for new salon lexan windows

Post here if you want to discuss a topic specific to the PDQ Altair.
jackfuller
deckhand
deckhand
Posts: 3
Joined: Sat May 23, 2015 9:12 am

Preparing surface for new salon lexan windows

Postby jackfuller » Mon Jun 01, 2015 9:47 pm

Any suggestions for how to prepare the surface for new lexan salon windows? I plan on using butyl tape and the screws which held the old windows in. '95 PDQ 32 classic. What adhesive am I going to be cleaning up. I have read the old postings on putting the new Windows on. Didn't see anything on cleaning up old adhesive.thanks

jackfuller
deckhand
deckhand
Posts: 3
Joined: Sat May 23, 2015 9:12 am

Re: Preparing surface for new salon lexan windows

Postby jackfuller » Tue Jun 02, 2015 10:20 am

Do you think I should go with lexan or plexiglass?

User avatar
thinwater
admiral
admiral
Posts: 1046
Joined: Mon Sep 22, 2008 8:08 am
Contact:

Re: Preparing surface for new salon lexan windows

Postby thinwater » Tue Jun 02, 2015 11:50 am

I don't think you want to use butyl. You need the bond from the sealant and you do NOT want pressure on the plastic or the plastic will eventually crack at the holes. Also, in my experience with the 32, the screws in the FRP are not good enough to depend on. They are not meant for that.

I love butyl for the aluminum hatches. Just not this.
Writing full time since 2014.

http://sail-delmarva.blogspot.com/2017/ ... store.html
"Keeping a Cruising Boat for Peanuts"
"Singlehanded Sailing for the Coastal Sailor"
"Faster Cruising for the Coastal Sailor"

Iriemon
skipper
skipper
Posts: 71
Joined: Mon Apr 20, 2015 11:05 am

Re: Preparing surface for new salon lexan windows

Postby Iriemon » Wed Jun 03, 2015 8:26 pm

Acrylic (plexiglass) is usually used for hatches and things like that because it retains clarity better and doesn't scratch as easily and you can buff it out to clear. Lexan (polycarbonate) is stronger, but scratches and can yellow over time. I'd probably go with lexan. If something were to come flying at the boat in a storm or hurricane ...

Here's a fun video to watch: https://www.youtube.com/watch?v=HlEfJFDWXpM

For mounting, first clean out the old sealant. A sharp chisel (carefully used to avoid chipping or scratching the fiberglass) will get the worst, sandpaper can get the fine bits left over. Clean with a solvent like acetone.

Use blue tape to tape off the edges on the boat and new plastic where you don't want the new sealant to end up. The time you spend taping will make up for itself in multiples in clean up later.

I'd use Dow Corning 795 as a sealant and nothing else. I've used all kinds of gunk to bed hatches and skylights, and nothing else comes close. Especially on plastics like plexiglass or lexan.

Use bits of neoprene or foam spacers about 1/8"(the kind the sell to space tiles work well) so that when you bed the plastic to the frame there is a gap for the sealant. Apply sealant, set the new plastic, and "lightly" put in the screws just enough to hold it in place evenly. You don't want to tighten it up at this time, because you don't want to squeeze out the goop. You want to leave a gap in there so it forms a good gasket.

Use your finger and lots of paper towels to smooth out the goop. Let the stuff dry for a day or two. Remove the tape. Now you can snug up the screws.

Edit: The goop to use is Dow Corning 795, I don't know where I got the 395 from that I originally wrote. It really is good stuff for bedding plastic. I've used to to rebed old hatches where I couldn't get all the old rubber/sealant out, just put the new 795 on top of some old rubber/sealant, and after several years, no leak and still good as new. It holds tenaciously. And my boat (Hunter 35) has acrylic skylights that I was lucky if I could get a year after re-bedding before I'd see leaks coming through. It's been going on 4 years with the 795 and not a drop.
Last edited by Iriemon on Thu Jun 04, 2015 10:36 am, edited 3 times in total.

User avatar
thinwater
admiral
admiral
Posts: 1046
Joined: Mon Sep 22, 2008 8:08 am
Contact:

Re: Preparing surface for new salon lexan windows

Postby thinwater » Thu Jun 04, 2015 9:56 am

A thought...

It is very handy to have snap-on covers, but the snap screws are a smaller size than the original screws (8 vs 10 I think). I have snap-on covers, but the screws come out once in a while. I think when I re-do the windows I may fill in all the old holes and relocate all of the screws a fraction of an inch./ I will still only use snaps on the corners and mid-points; I have never had a snap come loose and more screws would only be annoying and click if not used.

Any downside? The screws don't actually hold anything after the sealant is cured.

Image
Writing full time since 2014.

http://sail-delmarva.blogspot.com/2017/ ... store.html
"Keeping a Cruising Boat for Peanuts"
"Singlehanded Sailing for the Coastal Sailor"
"Faster Cruising for the Coastal Sailor"

Iriemon
skipper
skipper
Posts: 71
Joined: Mon Apr 20, 2015 11:05 am

Re: Preparing surface for new salon lexan windows

Postby Iriemon » Thu Jun 04, 2015 10:34 am

thinwater wrote:A thought...

It is very handy to have snap-on covers, but the snap screws are a smaller size than the original screws (8 vs 10 I think). I have snap-on covers, but the screws come out once in a while. I think when I re-do the windows I may fill in all the old holes and relocate all of the screws a fraction of an inch./ I will still only use snaps on the corners and mid-points; I have never had a snap come loose and more screws would only be annoying and click if not used.

Any downside? The screws don't actually hold anything after the sealant is cured.


Maybe if you filled the screw hole with epoxy or Marine Tex it would be strong enough to hold for your snaps?

User avatar
thinwater
admiral
admiral
Posts: 1046
Joined: Mon Sep 22, 2008 8:08 am
Contact:

Re: Preparing surface for new salon lexan windows

Postby thinwater » Thu Jun 04, 2015 4:22 pm

^^ Marine Tex doesn't generally do a lot for threads if the FRP is thin, which it is.

And filling the holes while the windows are in place sound very difficult. Nearly impossible to cleanout of the goop that is in there.

It can wait until window replacement time. They stay in for a while.
Writing full time since 2014.

http://sail-delmarva.blogspot.com/2017/ ... store.html
"Keeping a Cruising Boat for Peanuts"
"Singlehanded Sailing for the Coastal Sailor"
"Faster Cruising for the Coastal Sailor"

Iriemon
skipper
skipper
Posts: 71
Joined: Mon Apr 20, 2015 11:05 am

Re: Preparing surface for new salon lexan windows

Postby Iriemon » Tue Nov 29, 2016 1:09 pm

I had a couple cockpit front dodger snap holder screws pull out. I took a paperclip and bent an "L" shape in it, and used it to smear a generous layer of marine-tex on the inside of fiberglass around the screw hole, and then then hole itself to reduce the diameter. Once dry I drilled out the hole to a slightly smaller diameter than the sheet metal screw, then screwed the snap holder back in place.

Seemed to work well.

amytom
admiral
admiral
Posts: 688
Joined: Fri Oct 05, 2007 10:57 am
Location: Orlando, FL S/V DogHouse PDQ32009

Re: Preparing surface for new salon lexan windows

Postby amytom » Fri Dec 02, 2016 1:08 am

Where's a good source for the replacement windows?

Iriemon
skipper
skipper
Posts: 71
Joined: Mon Apr 20, 2015 11:05 am

Re: Preparing surface for new salon lexan windows

Postby Iriemon » Thu Mar 22, 2018 1:19 pm

A tip I picked up germane to this thread re: rebuilding worn out/stripped screw holes.

Use a small piece of cotton ball soaked in epoxy and push it through the worn hole. I used a couple bent paper clips to do this and to form the soaked cotton around the base of the hole as much as possible. I used this technique for holes I drilled to mount plexiglass covers for the cabin top skylight holes. I also used the technique to rebuild a stripped holes on the plexiglass windows, though I also dremelled out the front of the hole and added epoxy glass layers on the front for additional strength.

It seems to work pretty well.

User avatar
thinwater
admiral
admiral
Posts: 1046
Joined: Mon Sep 22, 2008 8:08 am
Contact:

Re: Preparing surface for new salon lexan windows

Postby thinwater » Thu Mar 22, 2018 10:35 pm

I bet these would work nicely, if you could find them.

Image

https://www.sailmagazine.com/gear/surefas-caf-compo-snap-studs
Writing full time since 2014.

http://sail-delmarva.blogspot.com/2017/ ... store.html
"Keeping a Cruising Boat for Peanuts"
"Singlehanded Sailing for the Coastal Sailor"
"Faster Cruising for the Coastal Sailor"


Return to “PDQ Altair (PDQ 32) Forum”

Who is online

Users browsing this forum: No registered users and 1 guest