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  1. 21st April 2009, 10:30 AM #1
    alzuger
    alzuger is offline Senior Member
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    Default Plywood Mast for the Pdracer

    I know this may seem foolish, but has anyone ever tried making a square mast out of 1/2" ply? When I was a carpenter building houses, we used to make many a structural box beam out of birch ply glued with internal butt plates. I am building a pd racer on the cheap this spring as practice before making the GIS. I want to use the lug sail and I have my spars roughly shaped already. I cant help being tempted to try the mast out of ply, I figure if it breaks i can row home and do it the right way. Any thoughts?
    Many thanks,
    Albert
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  3. 21st April 2009, 11:33 AM #2
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    Boatmik
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    Default

    Howdy Albert, and welcome.

    Basically plywood has half the woodgrain running across the mast doing little work to support.

    So as 50% of the grain is in the wrong direction the plywood needs to be almost twice as thick to be the same strength.

    So it is a way of building heavy masts.

    Plywood is brilliant for general loads, but not so good at the concentrated loads that masts have to deal with.

    Cheers
    Michael
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