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Re: Righting moment, sizing a mast

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  • Arne Kverneland, Norway
    Thierry, you may most possibly right. This is why I aim for a mast strength (breaking moment) that is 2-3 times stronger than the static max righting moment of
    Message 1 of 103 , May 26, 2013
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      Thierry,
      you may most possibly right. This is why I aim for a mast strength (breaking moment) that is 2-3 times stronger than the static max righting moment of the the boat.

      My point when dealing with this little 12' rowboat is that the number of people on board and the way they "ride" it will have a major influence on the total righting moment and thus on the stress on the mast.
      Cheers, Arne

      --- In junkrig@yahoogroups.com, "southcoveemail" <thierry.msika@...> wrote:
      >
      > Hi Arne,
      >
      > I am interested in the subject since I just barked a 29' long piece of a spruce tree trunk to make a mast in a couple of years. I bought a Shark 24' that I intend to junk rig in a couple of years. I cut the said slot along its length and the piece is now resting in the shade.
      >
      > You say:
      >
      > > Fitting a mast to your boat is not rocket science. The dimensions needed depend on how hard you intend to sail the boat. Two full-size men sitting on the rail of a beamy dinghy will produce a lot of righting moment and that would call for a thick mast. That is "worst case".
      >
      > But is it really the worst case? I would have thought that a boat pitching hard in a seaway or a steep chop would produce much bigger accelerations than any wind induced heel.
      >
      > What is your opinion?
      >
    • Arne Kverneland, Norway
      Thierry, you may most possibly right. This is why I aim for a mast strength (breaking moment) that is 2-3 times stronger than the static max righting moment of
      Message 103 of 103 , May 26, 2013
      • 0 Attachment
        Thierry,
        you may most possibly right. This is why I aim for a mast strength (breaking moment) that is 2-3 times stronger than the static max righting moment of the the boat.

        My point when dealing with this little 12' rowboat is that the number of people on board and the way they "ride" it will have a major influence on the total righting moment and thus on the stress on the mast.
        Cheers, Arne

        --- In junkrig@yahoogroups.com, "southcoveemail" <thierry.msika@...> wrote:
        >
        > Hi Arne,
        >
        > I am interested in the subject since I just barked a 29' long piece of a spruce tree trunk to make a mast in a couple of years. I bought a Shark 24' that I intend to junk rig in a couple of years. I cut the said slot along its length and the piece is now resting in the shade.
        >
        > You say:
        >
        > > Fitting a mast to your boat is not rocket science. The dimensions needed depend on how hard you intend to sail the boat. Two full-size men sitting on the rail of a beamy dinghy will produce a lot of righting moment and that would call for a thick mast. That is "worst case".
        >
        > But is it really the worst case? I would have thought that a boat pitching hard in a seaway or a steep chop would produce much bigger accelerations than any wind induced heel.
        >
        > What is your opinion?
        >
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