Window Specs

Discussion in 'Boat Design' started by We're Here, Aug 1, 2015.

  1. We're Here
    Joined: Aug 2007
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    We're Here Junior Member

    Am considering building a so-called semi-displacement workboat of about 30' x 11'. Top speed of about 24 and a cruise of about 14. Now the question: The boat will have to deal with a nasty inlet and prevailing northwesterlies offshore. I need windows that will reliably take these seas. The front windows will measure about 24" x 24" while the side widows are about the same. I've wasted considerable time trying to find glass specs for the Coast Guard's smaller boats and now I'm turning to the wisdom here. Thanks ... Alan
     
  2. kapnD
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    kapnD Senior Member

    Try downeast boat forums, plenty of discussion about the subject, right in your location too.
     
  3. We're Here
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    We're Here Junior Member

    The SNR is just too low there hence my asking the questions here. I'm far more confident of the data / advice given here.
     
  4. PAR
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    PAR Yacht Designer/Builder

    Assuming a 28' LWL, your "semi-displacement" hull form will be in full plane mode at 24 MPH, so maybe running this inlet, is more a skipper issue than a port or light size/material/build issue.

    As a rule, large ports/lights are to be avoided in anything that will see rough conditions, especially if blasting along up on plane. The prudent skipper will throttle back and run the inet at the speed necessary, to prevent undue concerns. Some inlets are notorious and difficult to manage. 4 square foot of exposed glass is a lot of area per port/light to worry about, but if this is fairly high up or well protected, maybe not.

    It might be simpler to just ask, what design are these going in or maybe you can post a sketch or photo of the proposed window arrangements.
     
  5. We're Here
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    We're Here Junior Member

    I mentioned hull speed capabilities only to provide a rough image of the boat itself, not by any means are these the speeds used in these difficult seaways! I am a licensed operator.

    To a certain extent, the bow itself will shed a portion of boarding seas before they reach the windows but as often as not the boat will be sliding down the backside of a sea when a boarding sea hits. It is this scenario that most worries me and I need windows that will shed these seas.

    Inlet seas can be confused and the side windows don't have any surfaces that will mitigate a boarding sea there. So these windows are a concern also.

    I could simply specify 1/2" 'tempered laminated' on all wheelhouse glass but is that needed? Cost is a concern but I will not 'cheap out' on this safety issue. Advice?
     
  6. PAR
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    PAR Yacht Designer/Builder

    Tempered lamy is pretty costly and you really need quite exposed posts to justify this expenditure. In most cases tempered will do. It really depends of the level of exposure. Simply put, if you expect solid green water on the ports, you might consider tempered lamy, but if you'll be busting up the green water pretty good with hull shape, their location and height, you'll likely easily get by with just tempered. You can also consider shutters on those rare days when conditions break down enough to have you a bit worried.
     
  7. TANSL
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    TANSL Senior Member

    The regulations of any classification society have clear instructions about the types that can be used for the "glass" windows and formulas for calculating the thickness, depending on its position on the boat, distance to waterline and other factors.
     
  8. gonzo
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    gonzo Senior Member

    Polycarbonate is a good solution for windows in those conditions. In the past I have installed them on boats fishing of Oregon inlet,NC that have similar conditions. A couple of them had glass windows busted. Sika makes a sealant that works well for plastics. They need either a metal frame on the edge, or large washers under the screw heads (if you are not concerned about cosmetics).
     
  9. We're Here
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    We're Here Junior Member

  10. gonzo
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    gonzo Senior Member

    That's the same kind of boat that longliners were using in the Outer Banks.
     
  11. We're Here
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    We're Here Junior Member


    I've tried but my efforts have gotten just a sales pitch for membership or handbook purchase. Excessive for someone considering his own build, eh? I had hoped for for a glass type / thickness 'opinion' that would receive peer review by other members of the forum. Frankly, this is the only truly independent source of this data that I have any faith in.
     
  12. TANSL
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    TANSL Senior Member

    I think Lloyd's regulations can be downloaded free from its web.
    I found the following. Maybe it works for you help.
     

    Attached Files:

  13. milo12
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    milo12 Junior Member

    Thanks for that info.

    I tried the Lloyd's site and couldn't find regulations. Do you have a link?
     
  14. TANSL
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    TANSL Senior Member


  15. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Attached an extract of the Spanish regulations for fishing vessels less than 24 meters.
    Sorry for mistakes in translation.
     

    Attached Files:

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