Replace windows questions

[Trick]

I am doing frame less windows on my San Juan 21
I was concerned about the over lap area being white through the the tinted acrylic. I saw someone on YouTube priming that area black on the backside.
I'm using the 3m tape and the Dow adhesive.
What primer is used.
Don't want that to compromise the seal.
Thxs
Trick

 

[kloudie1]

I used 1" wide black VHB tape to cover the overlap.. There was a thin (maybe 1/8") that didn't get covered. I masked that off and used a plastic specific "rattle can" to spray that and the area between the two windows since I converted to one "glass" per side. Paint came from Home Depot.. I did use the 3M #94 primer on the plexi and on the cabin side.. Note the little locator blocks that I hot glued to thhe cabin. When the plexi hits the cabin side, there is NO adjustment.. those blocks positioned it and then were easy to remove..

 

[Ralph Johnstone]

Note the little locator blocks that I hot glued to thhe cabin.

How tightly did the locator blocks hold ? Any chance of gel coat damage pulling off the blocks off or did you reheat.

Glued on blocks are the ultimate for positioning but just wondering .......................................

 

[Trick]

I work in a cabinet shop, and we use that method a lot works great
Was planning on using those.

 

[Artey1]

I have just used Rustoleum Marine Top Sides paint in black for this same thing, and it has worked beautifully. The paint is thicker than you expect, so thin coats, and need over 50* for it to cure.

 

[kloudie1]

Ralph, I did not prime or sand the spots where the blocks went on, just wiped down. They easily popped off. I used a hot glue gun and regular glue sticks.

 

[Project_Mayhem]

I used 1" wide black VHB tape to cover the overlap.. There was a thin (maybe 1/8") that didn't get covered. I masked that off and used a plastic specific "rattle can" to spray that and the area between the two windows since I converted to one "glass" per side. Paint came from Home Depot.. I did use the 3M #94 primer on the plexi and on the cabin side.. Note the little locator blocks that I hot glued to thhe cabin. When the plexi hits the cabin side, there is NO adjustment.. those blocks positioned it and then were easy to remove..
View attachment 199950View attachment 199951

Did you use any sealant or just VHB? If just VHB, any leaks?

 

[kloudie1]

After the VHB was well attached and the glass in place, I ran a bead of black Dow Corning 795 around the edge glass. Since the new glass was standing proud of the cabin side by its thickness, the bead made a kind of fillet at the glass edge. Since the VHB is a closed cell tape, I suspect it would be waterproof as is but didn't want to risk water freezing in the minute gap .. Yes it does freeze here a few times a year!

 

[Project_Mayhem]

I was actually wondering if the sharp corners on your plexi was giving you any issues but I guess that solves it. I've done some research on VHB and there's over a dozen different types. Some are recommended for window installation and some less so. It seems the RV industry has been using VHB for windows for a while now. The trailer industry uses VHB instead of rivets for sheet metal panels. Last time I looked it up it was more expensive for rivetless. I though the labor to do a few thousand rivets would cost more than the tape

I like the method you used. Did you use a trim ring on the inside?

 

[kloudie1]

I ran a 1/8" radius router bit over the edges .. ya can't really see it but I was a little worried about the sharp outer edge chipping. Then sanded the routed part.. "breaking" the edge with sandpaper is probably sufficient. I used the original inside trim rings ..
I spoke to a VHB applications engineer.. he advised the 1" wide, thick black tape, I think I got 5952 VHB, 1" wide.

 

[Hayden Watson]

I used narrow black VHB tape (1/2" that was laid very close to the edge of the opening and used a razor blade to trim it flush. I used black 795 to fill down to the VHB. The acrylic was "Dark Smoke" and I can see no shadowing through the glass.

 

[DArcy]

There may be a bit of confusion between the original post and some of the responses, of course the confusion could be all mine
It seems as though @Trick is asking about a primer on the back of the glazing material but some of the Rustoleum and rattle can paint seems to be applied on the exterior (hopefully).
When I put new acrylic windows on my C&C I bonded them in with Sikaflex 295. I used a black primer recommended by Sikaflex but I don't remember the product number. This worked really well with no leaks several years later when I sold the boat. I bonded the acrylic into the existing aluminum frames.

I should add that a friend used Sikaflex 295 based on my recommendation bonding acrylic windows onto his aluminum boat. He did not prep the surface properly, there was older paint that he did not remove, and his windows started leaking almost right away.
Surface prep is key to a good seal.

 

[Project_Mayhem]

There may be a bit of confusion between the original post and some of the responses, of course the confusion could be all mine

Im totally guilty of hijacking this thread. It's great to hear what worked and what didnt. While we're stating what doesnt work is butyl. The stuff just keeps oozing out of the frame! Anyways that's a discussion for another day.
@Trick Sorry for hijacking your thread. Has your question been answered?

 

[DArcy]

Im totally guilty of hijacking this thread. It's great to hear what worked and what didnt. While we're stating what doesnt work is butyl. The stuff just keeps oozing out of the frame! Anyways that's a discussion for another day.
@Trick Sorry for hijacking your thread. Has your question been answered?

I used Butyl tape as a temporary fix on my current boat between the frame and fiberglass and you are absolutely correct, it just keeps oozing out. I wouldn't use it on windows, too much flex.

 

[Project_Mayhem]

I suspect once it oozes out you may be left with a void