Plastic Pilothouse Windows?

Hey Froggman...

I did a technical article on this very issue over a year ago. I have been getting contacted on occaision for back issues and will finally get around to posting the article on the web tomorrow my time. I'll advise and give url upon completion.

I did the reserach with the pro's and found the tricks to making a true pro result. As in many things.... it's not rocket science, it's knowing a few tricks.

The better way is also the easier way and.... cheaper!! hows that for shock value.

Perspex/acrilic is easier to seal but requires greater thickness for strength.

Cheers

[Alan Wheeler]

I will look forward to that article Bob. I suggest you post it under it's own heading so as it will not be lost in the depths of a thread.

Darryl, intersting point you made. I have also had very positive experiance with Sika. But I was told by many "experts" in the window industry to stay away from it. They all recomended an MS adhesive sealant. But most MS sealants don't have anywhere near the strength Sika does. But you are also very correct, You MUST use the primer. The pimer is JUST AS important as the Sealant. Infact, it should basicaly be viewed as a two pack system.

OK... here it is http://www.thecoastalpassage.com/windows.html

I'll post it as a thread as well Alan, thanks for the suggestion.

I stress that this article is simple instruction intended for budget sailors who can think on their feet to insure the hot tips properly adapt to thier project. It's food not a feast!

On Sika flex.... I think the product exceeds what the maker calims for it. If it didn't work half the boats I know would be on the bottom today! But I think polyureathane has it's ultimate limits for flexibility/elasticity that even the best of the lot may not be able to overcome when it comes to polycarb. In the window refit referred to on the link. I didn't replace all of them. There were a few that were so sound I left them with their screws and Sika but they were the smaller ones, less area to expand. According to Sika, the sealant I used shouldn't have worked at all so...

The method and sealants refered to on the link are exactly the ones used in the production of a very expensive new cat here in OZ except they used mostly rebated channels where I am on a flat surface.


Cheers

[seafox]

It will be interesting to see how long my Sika lasts.
I went to an Altex painting evening on Thursday. A really interesting lady from Altex spoke all about their new roll on two pot paint.
She told us about contamination. A paint shop can be scrupulous in prep, wash and then wipe down with solvent etc. Spend ages sanding and everything. Then go to lunch. While they are at lunch a courier van backs into the workshop to deliver a package. Just a small amount of diesel fume goes into the workshop. Later the paint fails.
She gave us a demonstration of the paint after the talk. She had some primed panels and let anyone roll the paint on and layer it with a brush. She mentioned that when she was preparing the panels a diesel forklift went past one. Sure enough when this panel was painted a big circle appeared on the panel, not unlike a bacteria shaped balloon. All the other panels were fine. This one was contaminated.
She said that 1 part per million silicon will stuff a paint job. If you are painting outside and someone is using a silicon polish a few boats away it could be all it takes to stuff it.
I am sure Sika is the same. Humidity, prep, sunlight, wrong solvent to clean surface, all sorts of variables can probably stuff a good job. Even breathing on the perspex before you apply the sika could probably cause a failure. I know with other silicon based products this can stuff the job. Certainly does when glueing a dingy patch.

[Alan Wheeler]

Yeap your darn right.
So what was your verdict on the new paint?

yeah... it's funny.... we were al going nuts down south on the gold coast.. tiny pits in the final coat of poly U 400 .. (not my boat)

The cause finally worked out. A fish and chips shop a half a block away. Solution? no more painting or prep in a southerly!

I've always had good luck with Altex... AF 3000 antifoul is my normal among other of their products. pre prime 167 etc..

[seafox]

They developed the new paint as it was becoming so expensive to have a boat prof painted. To paint a 30 foot boat inside a workshop in Auckland was getting around $30,000. Most H28 or similar were not worth as much as the paint job. This product was developed so that person could paint their boat themselves for around $500 for the materials. It is obviously not as good as a spray job but with a bit of care and time a satisfactory job can be had. She showed us some photos of different boats that had been done by the owners and they looked good. She also told us stories about people who just rolled it on and liked the orange peel affect so never layered it off. I think that for the price it is a good answer for painting some of the rough cheaper boats you see around. If you own a $200k plus boat you probably wouldn't be happy with the finish.

[seafox]

One of the windows done over the summer of '95 has just started leaking big time. I will re do it with the sika.

Sika done properly in my opinion lasts 4 years.

[seafox]

should be $5 a tube not $39. It is pretty mediocre.

[Yachts66]

All my cabin ports (windows) are Lexan. Wretched material, I hate it. Here's why: A few years of direct sunlight and the material hazes over. My ports are so bad you can't see through them well at all. They also scratch way too easily. Replacing all these is on my very long list of things to do, so I'm not exactly sure if I will use safety glass or laminated glass, but I know I'll be using glass of some kind. My boat is steel, so the frames are integral to the cabin and not a concern.

Regards,

Thomas

[hellosailor]

"Lexan" is about as meaningful as "metal" or "wood". There are all sorts of different grades, and some of them are used in rather expensive and durable architectural glazing that does not haze up quickly. I would suspect someone installed the wrong grade, or made one of a number of simple errors, like allowing petrochemicals to contact the Lexan. (Assuming it actually is Lexan, because many folks use that name for many totally different materials.)

Yes, even the best polycarbonates will scratch much easier than glass. And react to a number of chemicals including the common petrochemicals found in ordinary waxes and polishes. But the polycarbonates also will keep a rogue spinnaker pole or column of green water from shooting into your cabin, when glass won't.

Incidentally, plastic headlight lenses on cars take a beating in the southern US. They inevitably haze over from UV and petrochemical haze on the roads. Solution? About $20 will buy you a "headlight restoration kit" or a couple of bottles of Novus polish. A little elbow grease, and they come perfectly clear again. And way stronger than glass.

Worth a try before you start reglazing.

[CarlF]

Interesting discussion by Steve Dashew on the use of glass for his powerboat. If you want strong glass - you can get it!

DashewOffshore.com - the serious cruising sailor's website

This is a few years old now. My understanding is that the laminated glasses have continued to improve as a result of the Florida hurricane driven building codes.

Sikaflex has a pretty good guide out for glazing. Done right, it's a lot stronger than screws and caulk but it's not like slapping a little caulk under a cleat.

www.sikaindustry.com/marine_direct_glazing_guidelines_aug_2004.pdf

(for some reason you can't click on the above link. Copy and paste it into your browser)

Carl

[barnakiel]

I do not think there is any difference between Sika urethane and Bostic urethane.

The Sikaflex material meant for windows is marked so on the container. Its Bostic equivalent too.

I have used Bostik (not "bostic") and they make some good stuff - on par with Sika and 3M.

b.

[hellosailor]

Carl-
"laminated glasses" The "hurricane windows" are actually not laminated glass, but three layers. Glass on the outside, and our old friend Lexan in the middle. So you could call it a "protected Lexan" window. There's a product called "MR-10" from GE that is Lexan with an anti-scratch layer on top of it, that's one of the types you won't commonly find at the corner plastics store--but used in architectural specs.
But again it comes down to costs, laminated anything is going to cost way more than cut plastics. Only an upscale market--or serious racer or cruiser--is going to spend for it.