Lightweight Pilot House Roof

Discussion in 'Fiberglass and Composite Boat Building' started by FromMystic, Dec 13, 2010.

  1. FromMystic
    Joined: Aug 2007
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    FromMystic Junior Member

    Hello,

    I'm working on my first major boat contruction project. We are designing the pilot house and are trying to keep the weight down.

    Was wondering what were some of the options for the roof of the pilot house? I'm new to composite contruction so if you assume I know nothing you'll be close to the truth.

    The roof as we have it designed has some shape to it. Any help would be great,
    Thanks FM
     
  2. alan white
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    alan white Senior Member

    The first question would be, how much thickness can you afford? You get the lightest roof when it can be thickest. If it can be three inches thick rather than 1 1/2" thick, materials can be oriented more vertically. If you are challenged for height, the material, whatever it is, will not be as vertically oriented and you will have to go more exotic or heavier.
     
  3. gonzo
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    gonzo Senior Member

    Composite construction can give you a lighter panel. However, it may not be as puncture resistant or be able to handle localized loads like grab bars without extra reinforcement. What are the design specificacions?
     
  4. War Whoop
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    War Whoop Senior Member

    What size are you talking about?
     
  5. PAR
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    PAR Yacht Designer/Builder

    I'll second Steve's request for more technical information. Lets start with the make, model and year of the boat. Can you provide any pictures? General dimensions of the pilothouse roof will be helpful as will it's use, such as will a fly-bridge be a possibility at some future point or will you have dance parties up on it every 4th of July? How much crown is anticipated and most importantly of all, will any compound curvature be expected?

    In short, you can have a really light roof, but if the rest of the pilothouse isn't saving much weight, then you shouldn't go crazy trying to make the roof a feather weight.
     
  6. FromMystic
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    FromMystic Junior Member

    Hello

    Thanks for the replies.

    We are working on turning a Crosby 21' Launch into a pleasure boat.

    The roof will be about 80 square feet. Supported on four corners.

    The will bw some camber in the roof but it does not need to be compound.

    Thanks again for the help, FM
     
  7. PAR
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    These aren't the fleshed out dimensions I was hoping for. So, basically you're asking for about 3 sheets of plywood, orientation unknown, to be arranged into a cylindrical or conically shaped coach roof.

    Assuming the about 10' fore and aft and 8' in beam, I would use a 6" crown, to insure the snow sheds in your neck of the woods. 3 mm plywood epoxied to 1" of closed cell foam on both sides will make a very light, strong roof, but it'll need a perimeter of solid wood (1x2) and solid wood fillers at the hard points (where she's posted). Naturally, you want to sheath the outside at least, both sides preferably. This is relatively inexpensive.

    Me, I'd use a different approach, because it's a Crosby. I'd use a laminate of 1/4" bead board (inside) and 1/4" plywood (outside). This would give her a traditional look and it would be self supporting over minimal cedar beams for a reasonable look and light weight.

    Both methods will require a temporary mold of some sort, but this is easy to make and can be knocked apart for other uses afterward.

    The roof could also be strip planked and cedar would again be my choice for the material. easing the two inside corners would make for a pleasing, traditional look as well. I'd use 1" thick strips, and rip them off the edge of 2 by stock, which will provide you with quarter sawn strips.
     
  8. FromMystic
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    FromMystic Junior Member


  9. PAR
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    PAR Yacht Designer/Builder

    That's a compound curve roof and will need to be molded. 1/8" diagonal layers, 1/4" diagonal layers, etc. It could be strip planked easily enough. It could also be done as a foam core, with laminate, depending on how into sanding you are.
     
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