Mast Compression Post Question

Discussion in 'Sailboats' started by Jetboy, Apr 23, 2015.

  1. Gary Baigent
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    Gary Baigent Senior Member

    Warning, Jetboy, swerve away from pedants, for your own good.
  2. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    Oh ggesss...same old trolls and their non-technical religious supercilious nonsense. Thread going down hill fast!!
  3. Jetboy
    Joined: Feb 2012
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    Jetboy Senior Member

    Physics is in many ways less useful than electrical engineering - which is really the engineering counterpart. Where electrical engineering class might bypass a deeper look at fourier transform analysis and filtering noise, the physics version would focus on that instead of a time on something like spending more time on learning circuit print optimization software. So the focus is just a bit different. In the real world, the actual book sitting on my desk right now is "Fundamentals of Electrical Engineering" that I reference more often than anything else on my bookshelf. And in reality the vast majority of physicists I know all do the same job - programming. I don't, but that's really what most physicists do.

    Mechanics isn't a major part of physics education anymore because physics tends to be theoretical and mechanics theory is pretty easy to cover in a semester or two, so little time is spent on it. I suspect that's why we are arguing semantics. From my chair calculating generally means both accuracy and precision - usually in a theoretical world. The math involved in this scenario isn't the problem.

    In the real world we have imprecision. No two sails are cut the same. No two mast extrusions are identical. No two winds are the same. I suspect that the load calculations using basic assumptions to simplify the process is reasonably accurate, but imprecise. And if we were to calculate all of the imprecision the results may not be a whole lot better than a good guess.

    I'm happy to use a well established "rule of thumb" so long as it seems intuitively reasonable and the alternative methods for selecting materials aren't likely to produce a better result. In the case of a compression post I suspect that the best view of necessary structure is that it be stronger than the mast. So long as the mast will buckle before the compression post, the rest doesn't matter. So my original question was how to size the compression post with respect to the mast. That's really the core question in my mind.

  4. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Perhaps what I'm going to say may seems a simplicity but here goes. The compression post will withstand the same load as the neck plus the weight of this, but its length is much smaller than the mast. Therefore, if you do not want to complicate your life, make a post compression of the same cross section as the mast.
    If any of the experts is in this forum that thinks everything is barbaric, has no more to say. At least I'll be happy to learn in this matter.
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