aluminum frame portlights or frameless acrylic?

[xavpil]

Hi friends
My 1980 cat 27 windows leak So I removed them. The aluminum frames are in a bad shape: bent, oxidize, glue marks, multiple unused drilled holes. getting them back to shape will be a lot of work and I won’t be able to make them look great.
On the other end frameless acrylic portlights seem pretty cost effective, easier to install.
Cosmetic wise I prefer clean looks so frameless on the outside AND inside, screwless is exatcly what I like.

The fact that I don’t really many people going this route makes me think I am missing something

Thoughts?

thx all

 

[kloudie1]

I went frameless a while back and I am really happy with the VHB tape and 795 sealant. Here is a link to Hayden Watson's post where he talks about the installation:
Replacing frameless acrylic fixed ports | Sailboat Owners Forums
The process for framed ports is the same. Cut the new acrylic so that the VHB (which is closed cell and waterproof) goes over the old screw holes and seals them.
Replace windows questions | Sailboat Owners Forums
And my note:
H-34 Fixed Ports Rebuilt | Sailboat Owners Forums

 

[Hollyberry]

Another vote for the DC 795 sealant, esp for the frameless method. Have done this on various boats over the years.
Have also seen 795 used to replace old rubber gaskets in otherwise still-healthy frames.

 

[xavpil]

Thx Claude!
I hope I find the key answer in these threads of "what type of acrylic do I need" because this morning I was strongly recommended by a great plastic shop in Milwaukee NOT to use acrylic if there is a chance it will bend to fit the shape of the boat. Even the slightest bent will compromise its structural resistance and it can/will break one day or the other. They said they served several customers who insisted and reported the windows eventually broke during install or later on.

 

[xavpil]

Another vote for the DC 795 sealant, esp for the frameless method. Have done this on various boats over the years.
Have also seen 795 used to replace old rubber gaskets in otherwise still-healthy frames.

do you remember the type of acrylic you used?
Did it have to be bent to conform to the shape of the boat or was it super flat?

 

[Hollyberry]

do you remember the type of acrylic you used?
Did it have to be bent to conform to the shape of the boat or was it super flat?

We used normal 'plexiglass', 3/16 or 1/4 (was a while ago, sorry) (not cast) typically available at plastics outlets. Not lexan or polycarbonate.
There was some compound curve in our cabin top but the acrylic conformed without a problem. I did have one crack in the first year.. suspect due to screw hole pressure... replaced with more care and it's still in fine shape 8-10 years later.
I'd also suggest the heaviest smoke tint you can get find.. looks best from outside, and appears totally clear from below.
Another trick is to dry-fit the new window, mask the outline and paint the overlay surfaces black before fitting the new. Then when you use black 795 there should not be anything visible under the acrylic..

I did use screws, at that point hadn't got the VHB tape memo....

 

[xavpil]

We used normal 'plexiglass', 3/16 or 1/4 (was a while ago, sorry) (not cast) typically available at plastics outlets. Not lexan or polycarbonate.

I'd also suggest the heaviest smoke tint you can get find...

I guess I didn't find the right product then because the maker/reseller says the sheets don't come tinted the way you describe it. They're either clear or color tinted....
Maybe I should ask him about plexiglass and not acrylic.

Thx!

 

[kloudie1]

HollyBerry is right on. Plexiglas is a trade name for acrylic. The optical best kind is the cast stuff. It is a lot more scratch resistant than polycarbonate (Lexan) and a lot more UV resistant as well .. My window had to bend some with the cabin and I had no problem bending it and attaching it without screws, but I was ready to put a couple of temporary screws in if I had to. The bend was about an inch and a half at the forward edge, starting about 24 inches back. I took dimensions to a local plastics shop and they cut the 1/4" Plexiglas to my drawing. I wouldn't go with less than 1/4" ; The prep and priming and cleanliness is mandatory for a good long lasting job. Look at the tints.. My original hatches and fixed ports were not the darkest smoke tint .. 57% light transmission, I think the tint nnumber was 2073.

 

[xavpil]

Another trick is to dry-fit the new window, mask the outline and paint the overlay surfaces black before fitting the new. Then when you use black 795 there should not be anything visible under the acrylic..

Awesome trick!!!! I just watched some videos of guys Who didn't get the memo about your trick. So don’t feel too bad about the tape memo!:-

 

[xavpil]

HollyBerry is right on. Plexiglas is a trade name for acrylic. The optical best kind is the cast stuff. It is a lot more scratch resistant than polycarbonate (Lexan) and a lot more UV resistant as well .. My window had to bend some with the cabin and I had no problem bending it and attaching it without screws, but I was ready to put a couple of temporary screws in if I had to. The bend was about an inch and a half at the forward edge, starting about 24 inches back. I took dimensions to a local plastics shop and they cut the 1/4" Plexiglas to my drawing. I wouldn't go with less than 1/4" ; The prep and priming and cleanliness is mandatory for a good long lasting job. Look at the tints.. My original hatches and fixed ports were not the darkest smoke tint .. 57% light transmission, I think the tint nnumber was 2073.

Thx Claude. Getting Great info here!!
i was think 3/8” thickness since I am sure I don’t need to bend as much as you had too

 

[Hollyberry]

I think 3/8" would be overkill the windows are fairly small on the C 27 ... finally found a pic of the curvature we had to work with...

 

[xavpil]

I think 3/8" would be overkill the windows are fairly small on the C 27 ... finally found a pic of the curvature we had to work with...

View attachment 210809

Thanks so much. It looks just awesome!
i Am thinking 3/8 because I’ve seen other posts and people used that size but also because when I see portlights that are sold that look like they could go on a tank or submarine I am wondering how much force is applied to them when navigating with the boat bones moving around …

 

[FastOlson]

I think 3/8" would be overkill the windows are fairly small on the C 27 ... finally found a pic of the curvature we had to work with...

View attachment 210809

That is similar to the factory installation of the four fixed port (external lens) polycarbonate lenses on our boat.
With both sealant and screws it is "offshore strong" . They never leak, altho there are some key techniques to doing the install properly.