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Glazing Question

Hi Steve, We just bought a 60’ aluminium sailing boat, 6 years old, and we are in the process of rethink many particulars for adapting the boat to our plans who are to sail even in cold places like Patagonia, and Antarctica. Your site is wonderful; a lot of passion is filtering in your words. A big wave destroying the glazing is one of our nightmares and so we found interesting your thumb rule for dimensioning the glazing. We’ve read of your concerns about laminated glasses, but you don’t talk about double glazing to reduce the condense inside the boat in cold places. May be because with such thicknesses is not an issue? Thanks a lot, Alberto
Hi Alberto: We looked at double glazing for Wind Horse and concluded that it was not strong enough. Also,the three folks who tried it all had condensation problems between the window panes.

Posted by Steve Dashew  (October 20, 2009)




6 Responses to “Glazing Question”

  1. Matt Marsh Says:
    I’m not at all surprised, Steve, that you’d be unable to find double-glazed units strong enough for Wind Horse. 19mm safety glass is not something most IGU (insulating glass unit) suppliers have in stock, or are willing to work with. And yes, a lot of double-glazed setups have condensation problems between the panes- especially up here in the Canadian winter. A possible solution would be to look for a commercial glazing supplier- the ones who do office building and airport windows. They should be able to fabricate custom double-pane units, using the thick safety glass for the outer pane, with dry argon filling and two-part silicone edge seals. They’ll be heavy and expensive, but it’s the only way I know of to get a condensation-proof cold-weather window.

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    Steve Dashew Reply:

    We considered commercial, but were unable to convince ourselves of the reliability. Inside condensation with single pane windows is controlled with a short period of air conditioning time to remove humidity. And we feel it is better to pay the heat loss penalty of single pane than have t he hassle of problematic sealed windows (we have lots of heating capacity).

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  2. Dion Poncet Says:
    Double glazing on boats cruising in the antarctic is considered an absolute necessity. I could not imagine not having it in any temperate climate. Most boats double glaze their windows and hatches by adding a light perspex or acrylic layer on the inside, fixed to the interior lining or window surround. I have seen these fixed by woodscrews, velcro, foam rubber. Obviously it will not be hermatically sealed and it doesn’t have to be. Sometimes if fogging is an issue a small hole is drilled in the perspex near the top edge of the window to allow some circulation of air and let moisture out. This solution is simple and cheap and pretty much standard for yachts in this area. Without it the energy loss is enormous and the condensation will be staggering; literally raining inside the boat. Unless you have a very powerful heating system then the boat will never be warm and dry, I have seen a quite a few wet and miserable yacht crews in the antarctic before.

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    Steve Dashew Reply:

    Hi Dion: There are two issues involved. One is heat loss, and in this case some form of plastic window doubler makes sense, especially if you are spending long periods in the cold. However, the doubler is going to leak, and this means cloudy windows. Our logic on Wind Horse and the FPB64 is to pay the heating penalty and maintain window visibility. This works in Svalbard and Greenland type environments in the summer as we rarely see temperatures much below freezing. But if we were wintering over, or fighting the spring ice, then we would agree with you. Besides, you have way more experience in the cold than do we!

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  3. RAN Says:
    I once worked for a company that sold the type of windows you might want for this environment. Between the edges of the argon filled panes was 3/4″ width of a gray mastic like goop. No car door type seal will work for long. This window had a double lifetime free replacement warranty against condensation. I don’t think they gave away many windows. Just the 500,000 sweat glands in your feet can produce a pint of water each day. Add in breathing, showers, and cooking with gas and you have lots of moisture to expel. What provisions for fresh air exchange are there in the HVAC system?

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    Steve Dashew Reply:

    We need to use laminated windows for structure. HVAC fresh air make up, if desired, is via Dorade vents.

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