Storm boards for windows

[Ryban]

Thanks, that makes a lot of sense. I'm going to order both products.

So the building material supplier on island has sheets of clear plexiglass (acrylic) 1/4" thick, but nothing thicker.

This seems thin to me, but I'm having my doubts that I'll find 3/8" without having to have it shipped in.

[Copacabana]

Originally Posted by Ryban

Thanks, that makes a lot of sense. I'm going to order both products.

So the building material supplier on island has sheets of clear plexiglass (acrylic) 1/4" thick, but nothing thicker.

This seems thin to me, but I'm having my doubts that I'll find 3/8" without having to have it shipped in.

It shouldn't be too hard to find 1cm (3/8th). Have you tried sign shiops and people who do canopies and window awnings? They can also cut it for you.

[Ryban]

Originally Posted by Copacabana

It shouldn't be too hard to find 1cm (3/8th). Have you tried sign shiops and people who do canopies and window awnings? They can also cut it for you.

I tried a sign shop, but they said they sourced their material from the building material supplier that I had called. I'll keep searching.

I might sail up to Martinique before heading off to Panama though, so I'll look into whether I can get the appropriate material there, as well.

So many times I wish I wasn't on an island.

[noelex 77]

Originally Posted by Ryban

Thanks, that makes a lot of sense. I'm going to order both products.

So the building material supplier on island has sheets of clear plexiglass (acrylic) 1/4" thick, but nothing thicker.

This seems thin to me, but I'm having my doubts that I'll find 3/8" without having to have it shipped in.

1/4" acrylic on its own would not be strong enough but combined with the existing windows should be very tough structure.

How large are the windows, and how far are they above waterline?

[Jim Cate]

Originally Posted by dixiedawg

My windows are roughly 1" larger than the openings all the way around. The VHB tape is centered in the middle of that inch, and the 795 is squeezed under the Plexi from both outside and inside. The tape is thus completely sealed in by the 795, inside and out.

Yes, I used 4991. To be honest, I just blindly took Casey's advice in that area. The DC 795 I was familiar with already and believed it to be the best.

Dawg, how wide is the tape, and how thick? I've never done a window this way, and am a bit confused as to the method. Do you put the tape on the hull, lay a bead of sealant on each side of the tape and then set the glazing down on it until the tape holds it in place? If so, what keeps the sealant from squishing over the tape before t he glazing gets in contact with the tape?

Or is the sealant introduced after the tape is holding the glazing in place?

Sounds like a good way to install glazing, one that does not cause the cracking that screws do.

Jim

[Ryban]

From what I understand, that 3M VHB tape is structural tape, and essentially permanent adhesion. The silicon just helps seal the window from water intrusion. I don't think the silicon can seep past the tape.

Good news! I found sheets of 3/8" polycarb and acrylic. It turns out one of the chandleries here stocks the material, it's just in the back room.

It ain't cheap though. The acrylic is $14 sqft. But beggars can't be choosers.

[Gene Neill]

Originally Posted by Jim Cate

Dawg, how wide is the tape, and how thick? I've never done a window this way, and am a bit confused as to the method. Do you put the tape on the hull, lay a bead of sealant on each side of the tape and then set the glazing down on it until the tape holds it in place? If so, what keeps the sealant from squishing over the tape before t he glazing gets in contact with the tape?

Or is the sealant introduced after the tape is holding the glazing in place?

Sounds like a good way to install glazing, one that does not cause the cracking that screws do.

Jim

The tape is applied first to the windows, which are pressed into place and firmly held by the tape. This makes it very easy to apply the silicone into the remaining gap inside and outside the boat. Both the tape and the DC 795 are considered structural grade adhesives. The tape is about 1/2" wide, but I don't remember the exact thickness offhand. I would say 1/16"?

[Ryban]

I just ordered a few tubes of 795 and 4 rolls of 3M VHB to be shipped down here. It won't be super cheap to have it imported, but cheaper than the 60 something SS bolts, washers, and nuts would have been. Plus, I like the idea of not having drill all those holes, either in the plastic or through the boat.

I also found a friend in the boat yard that has a circular saw and a handheld router that he's letting me use to cut the windows. Hopefully this goes well. I know it can be a tricky business...

A bit off topic, now that this thread has gone from storm boards to new windows, but I found this picture of my boat from when it was being sailed around the world in the 80s. Their solution was to affix clear polycarbonate outside the existing windows on teak rails -- similar to one of my early proposals.

[Ryban]

Just wanted to provide an update.

This project has gone well so far, but I have learned a lot along the way and will probably make a dedicated post with photos and instructions on how everything was completed.

Cutting the acrylic wasn't too difficult using basic tools. I used a circular saw for long straight cuts, and for roughing out the shape. I then used a jigsaw with a fine-toothed blade to cut as close to the line as I could manage. Unfortunately, I couldn't find any plastic blades for the jigsaw on the island, but managed just fine with the metal one. I finished the edge with a hand-held router, which was time-consuming work, but left a nice edge. I then sanded this down progressively for a smooth, but not-quite polished finish.

I then cut free the protective film around the portion of the perimeter of the window that overlaps the hull, and painted it with matte-black Fusion spray paint for plastics. It uses an acrylic binder, and, at least from what I've read, shouldn't compromise the integrity of the final bond. I think this step is very important in order to achieve an aesthetically pleasing final result.

Fitting the bigger windows on the boat was a trick job. I'm on anchor and by myself, but I managed. One trick I employed was to use blue masking tape, aligned up and down, to create a few hinge points on top edge of the window. This way, I can carefully adjust how the window was "hanging" over the opening, and get it in the right position without needing 3 hands. I then marked the hull in a few places, but left the painters tape hinges in place, and flipped the window upside down atop the deck above the window opening.

The VHB tape is tenacious, and once bonded, won't come off easily. I applied the tape to the window first, rather than the hull, and I did so in one continuous strand. I read somewhere that a good trick is to lift the film on just one corner, leaving a tab sticking out that you can grab once you've positioned that corner. After doing that, I flipped down the window, still hanging on it's tape-hinge, and carefully positioned that same corner. I then grabbed the red tab, and pulled up, which progressively revealing a new bonding surface to the hull, and leaving me in full control of ensuring that alignment was perfect. I then proceeded pulling the tab all the way around the perimeter of the window. Worked brilliantly. A note of caution with this method is that, if somehow the red film gets caught, or breaks, you might be in a bit of a pickle, as I don't know how you'd be able to remove the rest of the film, as the gap between the hull and the window is much too small to reach in there and get a hold of it.

Another note about the VHB tape. I used a version that was 1.2 mm thick, but I'd recommend getting the 2.3mm one if you can. A thicker tape gives you a bigger gap for the silicone adhesive to fill, and thus more flexibility without compromising the silicone bond to either surface.

It's also very important to firmly press all the way around the perimeter of the window, especially if there is a slight curve in the hull. And I mean press hard! I thought I pressed hard enough the first time, but noticed a few gaps at the ends where the tape wasn't contacting the hull.

Working with the silicone isn't as bad as most people say. I masked off the hull 1/4" along the perimeter, and squeezed the silicone into the gap between the window and hull. Depending on your boat, getting the portion beneath the window can be tricky and very frustrating. I bought syringes for just this purpose. You can clean up your oopsies with a rag soaked in mineral spirits. I tooled the silicone with my finger, and removed the tape immediately.

I'm not sure how long it takes for this stuff to cure, as even the next day, the bits that I had dripped on a piece of scrap wood did not seem cured. Someone had warned me about this in advance, and I don't know if it has to do with the environmental conditions, or if it's just a really slow-curing silicone.

I still have more windows to install, but once the job is complete, and once I have time, I will make a full post.

[Gene Neill]

A couple things I would have done differently ... too late now, but in the event you have problems (hopefully you wont!!) at least you'll know why.

One: the paint was not necessary for aesthetics. The gray tape against the black slicone is indistinguishable through the smoked acrylic. Hopefully the paint bonds as advertised so this will be a non issue.

Two: I was strongly advised to "burnish" the edges of the acrylic with a blowtorch as a final finishing step before installation. Apparently it reduces the chances of microscopic cracks in the edge enlarging into meaningful ones. Again, hopefully it's not that important.

And yes, Dow Corning 795 takes forever to cure. It was "cold" here (low 60's F) when I did mine, and it took days to get set.

Congrats on getting it done! Pics are demanded! And Happy New Year!

[Cheechako]

Yes, the edges can be heat polished with a torch. One needs to pay attention to the movement and time though! It comes out perfectly smooth just like the flat surface if done right.

[CarlF]

Congrats.

You've essentially made a "bonded" window. The great thing about both VHB and 795 is they are elastic - as is fiberglass and plexi. That whole assembly will take a lot of punishment before letting go. Bolts and frames create an inelastic hard spot with different thermal expansion properties and then depend on a sealant to fill the inevitable gaps.

Automobiles have bonded their windshields for years. CG bonds instead for frames too. Good piece from SikaFlex on using bonding instead of frames.

http://fr-marine.com/Images/UpFile/201171292438717.pdf

I find myself using 795 for more and more boat applications. It applies neatly, looks good years later, and never seems to fail. I'm trying to figure out what it's not good for (I don't use it below the waterline).

[Ryban]

I ended up buying the white-colored 795, thinking that it would be less conspicuous on my white hull. With the tape being a dark grey, this was a poor choice, and that's another reason I decided to go the paint route. I'm also not convinced I would have been able to completely fill the gap down to the tape with the 795. The problem with the white though is that, since I used a black paint, and my hull isn't completely white, it contrasts both. Black would have been better.

I want to re-iterate that if you can get the 2.3mm thick tape, then do so. It will be easier to work with on all accounts, and also create a more flexible bond.

I did my second large window today, but because my hull slightly curves, I was having a hell of a time getting one of the sides to make contact. The harder I'd push against that edge of the window, the more the hull would flex away as well, thus becoming a trying endeavor. I eventually got in my dinghy and went to one of my neighbor's for help. He pushed hard on the outside, while I pushed back on the hull from the inside, the tape made contact, and a bond was formed. I believe if my tape was the 2.3mm variety, this wouldn't have been so challenging.

I am happy with the way things turned out. I'm hiding the bare inside edge with my curtains, but this is something that should probably be addressed with some tirm work.

[Hasbeen]

One little trick we used to ensure things like windows & deck hardware did not leak.


Fit the item with Silicone of Sikaflex, & only very gently secure.


Come back a couple of weeks, or even better a month later, & fully tighten the item. Now you were not only using the sticking properties of the material, but had compressed the cured material as a gasket, giving even better chance of a leak free boat.

[Don C L]

Good work! Got some photos perchance?