Resistance prediction for a large B/T

Discussion in 'Boat Design' started by pavel915, Sep 26, 2010.

  1. pavel915
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    pavel915 Senior Member

    I usually use Holtrop and Mennen modthod, Series-60 etc for resistance Prediction. But the boat we are now designing is of a B/T =6 which is not compatible with Holtrop and Mennen or Series 60.

    Particulars of the boat are:
    Lwl=40
    Bwl=8.4
    Draft=1.4
    Cb=0.5
    Service speed=12 knots

    Would you please tell me if there is any other method for resistance prediction for boats of this dimensions?
     
  2. Perm Stress
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    Perm Stress Senior Member

    Try Fung prediction method.

    it works well with high B/T.
     
  3. pavel915
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    pavel915 Senior Member

    Thanks a lot for your reply.

    Can you please give any paper which describes Fung Prediction method?
     
  4. b1ck0
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    b1ck0 Senior Member

    I think this is what you need :)
     
  5. pavel915
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    pavel915 Senior Member

    Thanks a lot bicko,
    But in my boat, the transom is not immersed, so will my boat be still compatible with fung method?(As I came to know that this method is for transom hulls)
     
  6. b1ck0
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    b1ck0 Senior Member

    I can't give you an answer to this question because I simply don't know. Sorry :)
     
  7. pavel915
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    pavel915 Senior Member

    Its okay b1ck0, your helps were appreciable,
     
  8. baeckmo
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    baeckmo Hydrodynamics

    Pavel, what is the L/B ratio and the slenderness ratio (L/(Displ)^0.33)? It might be possible to find something useful if we change perspective!?
     
  9. pavel915
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    pavel915 Senior Member

    baeckmo,
    my boats L/B =5 and slenderness ratio= 6.75 (displacement =220 m^3)
    Sorry I did not understand what you said by " It might be possible to find something useful if we change perspective!?"
     
  10. Leo Lazauskas
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    Leo Lazauskas Senior Member

    NavCad has several empirical resistance prediction methods. Have you looked at what they offer to see if any apply to your vessel?

    All the best,
    Leo.
     
  11. baeckmo
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    baeckmo Hydrodynamics

    What I meant was that you are looking for a solution that primarily satisfies the "B/T"-criterion. If we instead take a look "from another angle", say slenderness ratio, we may come up with something useful.

    Since slenderness ratio is a primary factor regarding resistance in this speed range, while B/T is more of a secondary factor, a search among methods based on slenderness may be a better start than to use B/T.
     
  12. pavel915
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    pavel915 Senior Member

    Thanks baeckmo,
    your words are now clear to me.
    nice to know the info that slenderness ratio should be my criterion.
    I will study that what method may suite my boat with that criterion but would you please suggest me any method for the slenderness ratio of my boat?(as you are more experienced one)
     
  13. pavel915
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    pavel915 Senior Member

    Leo,
    If the slenderness ratio is the criteria, in what range of slenderness ratio michlet will be good?
     
  14. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Unfortunately, Michell's thin-ship theory has nothing to say about the slenderness ratio. It requires the longitudinal hull slope to be small.

    Apart from Navcad, you could also see what standard empirical formula are available in Maxsurf.
    Good luck with your search!
    Leo.
     

  15. pavel915
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    pavel915 Senior Member

     
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