sailboat prototype weight

Discussion in 'Sailboats' started by Ron Skelly, May 25, 2013.

  1. Ron Skelly
    Joined: Nov 2009
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    Ron Skelly RonS

    Is there a formulae to figure out the ideal weight thay my new sailboat should be? Its a new small sailboat design. Any help appreciated.
    Ron S
     
  2. T0x1c
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    T0x1c Junior Member

  3. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    No, there isn't. Boats of the same length designed for different purposes will vary in weight by about a factor of ten. You design a sailboat not to capsize, and not to come apart. It ends up weighing what it needs to weigh to stay upright and in one piece and provide the necessary accommodations. So you design or select every piece and calculate it's weight and add them all together. Pages and pages of 3 ounces for this, 6 ounces for that, etc. You track the vertical and horizontal and transverse location of each also so you can find the center of gravity.

    Some free software lets you assign a density to the hull plating and will calculate the weight of that if you correctly set the layer properties to reflect changes in hull densities.

    Spar builders should be able to provide the data for the spars pretty much complete. Same with sailmakers. Generally, you start with estimates and work all the isues as rough approximations, then refine and go around the loop again. See the thread on the design spiral.
     
  4. Doug Lord
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    Doug Lord Flight Ready

    Here are two compendiums of statistics for mostly performance dinghies. This may help you get in the ball park. Also below is Eric Sponbergs collection of Design Ratios which goes into the why and wherefore of these ratios. He did this to help people like you and me and donated the work to all of us.
     

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  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Ron, one of the very first things done, with a prospective design is a weight study. With this in hand, you can decide on a midship section and general Cp for the performance envelop you want, given the load you'll expect.

    To directly answer your question, you'll have to provide a whole lot more information. There are some graphs and charts, that have popular and common design parameters plotted out, so you can see where one design rates against another, but frankly these are essentially useless, unless you understand the dynamics and principles involved in selecting the individual parameters, for any given design.
     

  6. Petros
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    Petros Senior Member

    for a small dingy that is designed to be carried or roof top to the water and back, the ideal weight is a light as possible. This is also true of boats designed for trailering, but you compromise their on-water performance without a weighted keel if it is too large to us the crew weight to counter balance the heeling moment from the sails.

    So for any boat designed to be easy to transport, there is no "ideal" weight, it will be a compromise between portability and sailing comfort. This is also true for large deepwater sailboats, heavy pleasure cruisers tend to be slow but more comfortable in rough conditions as compared to a lightweight ocean racer. Again there is no "ideal" but rather a compromise between design objectives.

    what size boat are you considering and what is the intended use? trailer sailor, smaller fixed keel boat, dingy, tender, or what?
     
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