Portlight Help Needed

[rbk]

Originally Posted by CptCrunchie

What do you think about bronze tinted Lexan?

https://www.ebay.com/itm/LEXAN-SHEET...bq1d:rk:1:pf:0

The stuff is practically bullet proof, I can take it into my woodshed to make the lenses, and is readily available at an excellent price.

I'd likely even coat the inside with a UV reflective coating, though I'm not sure I need to.

You can also get tinted auto glass for this. Be careful with the depth of the ‘glass’ as there is generally an inner channel with fasteners that hold the glass in. You may need to source new ones if the depth of there glass is deeper than what it was designed for. Also make sure it can close with thicker glass before making a dozen.

[a64pilot]

My opinion is that laminated glass is superior to lexan.
Lexan is extremely tuff, but it’s also very soft and scratches easily, there is hardened Lexan that helps with the scratching issue.
We looked at using Lexan for the windshield on the crop duster, crop dusters often hit birds and need a tough windshield, Lexan met the toughness requirement, but scratches so easily and doesn’t last long in the Sun so we stayed with laminated glass.

[Reefmagnet]

I've got very, very similar looking portlights that also have a big bronze deadlight attached - most probably because these mount in the hull. On mine, the "glass" pane is 8mm acrylic and is mounted in an open frame and held in place with an adhesive sealant. The design is such that when the window is closed, the pane is forced against a seal in the portlight body and this means that it doesn't (shouldn't!) leak and the pane is prevented from being dislodged if smacked by a wave.


Personally, I would prefer cast acrylic to glass or lexan because it is the best compromise of life span and toughness. I replaced my panes recently with 10mm tinted acrylic (mainly because it proved difficult to get 8mm tinted, and I had some 10mm stuff lying around already). To make the new panes, I fabricated a template from MDF material, carefully shaping it for neatness until it fit the frames of the portlight and then used a trim router and pattern bit to shape the acrylic after rough cutting it from the sheet (which is really messy and produces lots of acrylic "snow" flakes). Glued them in with some clear polymer adhesive sealant and good to go.

[Exile]

My understanding is that Lexan's strength may be better for overhead hatches which may get stepped on, etc., but where scratching may be less of a concern. Acrylic is better for portlights since, as a64 says, it doesn't scratch as easily and so lasts longer before your views to the outside become obstructed/foggy. This is what the factory used on my boat for its hatches & portlights.

I agree that glass for portlights is probably best of all durability-wise, and tempered is the usual recommendation. It is expensive, however. Laminated is cheaper but I've read where, over time, the glass can get obscured along the edges from the laminate. I was ready to replace my crazed/foggy acrylic portlight lenses with glass until I discovered they were thicker than the usual standard, thereby making it difficult and certainly more expensive to get customized glass in the thickness needed.

And yes, different types of sealant required for plastics vs. glass. Wanna be sure to get that right.

[CptCrunchie]

Originally Posted by rbk

A64’s correct. It usually has to do with using polysulphide sealant (or another type I can’t remember right now) bedding the glass, it attacks the plastic laminate in the middle causing it to ‘fog’ over. Re-bed with butyl, if a sealant was used you may have a hard time removing the glass without breaking it. They are strong but once leverage is placed on the glass as you remove them they tend to break rather than bend. Polysulphide and other sealants (again can’t remember) are not supposed to be used on plastics including lexan, acrylic etc but people regularly bed plastic with them and they more or less rot where sealant makes contact.

Hmmmmm...... Fogging in the middle? The polycarbonate sheets are solid. And I'd be using this, and this polysulfide sealant, which is recommended.

https://www.jamestowndistributors.co...oaAjxqEALw_wcB

This has also been recommended, and I have used it to reed the hatch on my Trophy 2459 Offshore.

https://www.bestmaterials.com/detail.aspx?ID=19987

Is there something better? I'd also be using it to re-bed the windows and hatches, which means it will be metal to fiberglass/gelcoat.

If not, guess I'm back on the search for the proper lenses.

[Uncle Bob]

Originally Posted by a64pilot

It may have some form of sealant holding it in, so it may not just fall out, but look hard at it and I think you will see what I mean.
Mine are 32 years old and that one I took apart has some delamination around the edges, I was going to replace it but haven’t bothered yet.
Mine that has delaminated has the air conditioner blowing directly on it, so it sweats in Summer cause it’s colder then the air, I suppose that is why it delaminated.

Tempered glass will break just about as easily as regular glass, it just breaks into small pieces that are way less likely to hurt you, shower doors etc and all other windows on a car are tempered except the windshield.
The windshield is laminated AKA armored glass, it has the plastic in between two layers and will stay together even if smashed.
The staying in one piece as opposed to turning into glass gravel if broken is why I think laminated is better for port lights myself.

I think it’s way harder to get tempered glass custom cut, I’d think cutting it may make it shatter, and maybe it has to be cut first, then tempered, something I wouldn’t think a small glass shop could do, laminated glass can be custom cut, because where I worked we had the local glass shop cut all the windshields for the crop duster we made.

This is pretty much what I would do, laminated and sealed with the type of sealant that auto windscreen installers use. Sikaflex make one I believe that works well.

[rbk]

Hmmmmm...... Fogging in the middle? The polycarbonate sheets are solid. And I'd be using this, and this polysulfide sealant, which is recommended.

Not with PC, with laminated glass. There is a plastic sheet laminated between the two panes. That’s why the fogging starts around the edges where the plastic is exposed. As for PS and plastics it’s well documented
What Sealant Do You Need - BoatTech - BoatUS

[Exile]

Originally Posted by rbk

Not with PC, with laminated glass. There is a plastic sheet laminated between the two panes. That’s why the fogging starts around the edges where the plastic is exposed. As for PS and plastics it’s well documented
What Sealant Do You Need - BoatTech - BoatUS

As the Casey article confirms, I used BoatLife's LifeSeal with good success when replacing my Lexan hatch lenses awhile back. The stuff is good at going everywhere you don't want it to go so I went with the clear. As mentioned, there's a specific type of SikaFlex that's recommended for glass. Not sure about laminated glass specifically.

[CptCrunchie]

Originally Posted by rbk

You can also get tinted auto glass for this. Be careful with the depth of the ‘glass’ as there is generally an inner channel with fasteners that hold the glass in. You may need to source new ones if the depth of there glass is deeper than what it was designed for. Also make sure it can close with thicker glass before making a dozen.

My intention is to take one apart, duct tape it over until the new ones arrive or are made, so it will be the correct thickness.

[Red Sky]

The manufacturer could be New Found Metals.

[rbk]

Originally Posted by CptCrunchie

My intention is to take one apart, duct tape it over until the new ones arrive or are made, so it will be the correct thickness.

If you really want to secure it, a couple of cutting boards some carriage bolts, washers and nuts sandwiched over the rough opening and a bead of butyl around the outside will make it watertight and secure while you have them out. If you can make 2-4 rigs then just move them as you go.

[Uncle Bob]

Originally Posted by rbk

If you really want to secure it, a couple of cutting boards some carriage bolts, washers and nuts sandwiched over the rough opening and a bead of butyl around the outside will make it watertight and secure while you have them out. If you can make 2-4 rigs then just move them as you go.

Or just do as you suggested, take one out, have the required number made/purchased or whatever and replace one at a time at your leisure.

[chowdan]

I would suggest pulling the glass and taking it to a "foggy window replacement and mirror replacement" company.

They often are able to order custom cuts on any type of glass from glass manufacturers. Most of the time the glass company will create a template(due to shape) and the manufacturer will cut the glass directly. They often have some tolerance in the cut(often 1/16").

I would recommend going with laminate as its just 2 layers of tempered glass laminated together with PVB(polyvinyl butyral). The benefit of laminate is that it wont shatter all over your boat, it will just shatter and stay together.

Tempered glass is easy to break when struck on the edge, not so easy when face on. Tempered glass is softer than annealed glass, but not as soft as lexan.

Where are you located? I do a lot of custom mirror/glass replacements and if you are near Seattle I'd be open to helping you get new glass. As a side note, glass shops probably be happier to service you if you had a template premade and you said I want this made to match this. Often times it's not worth a glass shops effort(ie they will say no, or price will be high)

[JPA Cate]

Lexan is hard to maintain in a sea water environment. Some of the automotive lens polishes are designed for it, though, so are relatively easy to find, especially in first world places.

Ann

[a64pilot]

Lexan is hard to maintain period.
It would be far superior bird strike wise for an aircraft windshield, but you don’t see any windshields made from it.
That is because you have to be able to see though a windshield.

Just read the last paragraph
http://www.aircraftwindshield.com/faqs.html