Dry tank testing. Can there be such a material?

Discussion in 'Sailboats' started by Omeron, Jan 30, 2008.

  1. Guest625101138

    Guest625101138 Previous Member

    Michlet uses Michell's thin ship theory for determining wave drag, has a choice of ITTC1957 or Grigson for viscous drag and also has a component for calculating transom drag.

    I have found it gives reliable results for efficient hulls. The drag on such hulls tends to be dominated by viscous drag anyhow. Modern sailing craft are using more slender hulls such as trimarans, catamarans and canting keel yachts. These boats are designed to stay upright as well so heel is not a key concern.

    If the hull is designed to plane then Savitsky gives reasonable accuracy. I was a little surprised that Michlet and Savitsky are not too different at the bottom end of the planing range.

    There is a post here that compares Michlet with CFD and actual data:
    http://boatdesign.net/forums/showthread.php?t=20497
    Curves attached.
     

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  2. nico
    Joined: Jan 2003
    Posts: 190
    Likes: 6, Points: 0, Legacy Rep: 52
    Location: SF

    nico Senior Member


  3. fastwave
    Joined: Jan 2007
    Posts: 112
    Likes: 15, Points: 18, Legacy Rep: 36
    Location: europe

    fastwave Senior Member

    Nico,
    to make it 150 point you need a lot more computing power than 16 processors for the runs I am talking about. Although the comptures might be cheap the licenses are no that cheap. so 80euro a point is very very difficult to get.

    on 16 processors you will be lucky to get a point/24hours. You will only achive this if you have a very good and developed sustem in place.


    With regards to people still saying that full appended runs are not possible, I only have to say the following:

    1. It is done.
    2. Quoting Ian Campell and Andy Claughton, is not representative. Both work, worked for the wolfson unit which is a big time fan of tank testing and not a great supporter of CFD.

    people seem to know a lot about AC teams on this forum, but I wonder how many actually have a good insight of what is going on.
     
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