Preliminar power for catamaran

Discussion in 'Diesel Engines' started by Van Callum, Mar 20, 2025.

  1. Ad Hoc
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    Ad Hoc Naval Architect

    As noted above by baeckmo, it is the slenderness ratio....a measure of how "slippery" a 3D shape moves through the water.

    So, in your case a length of 5m, with a displacement of 1000kg (or 1.00 tonne) the LD ratio = L/(displ)^1/3 = 5/1^1/3 = 5.0.

    If you look at the basic trends of vessel with speed v resistances over a series of different LD ratios, you get this:

    upload_2025-3-24_10-38-50.png

    As you can see an LD ratio of circa 4-5, is not good. Whereas an LD ratio of 8-10 is significantly better.

    Simply put, minimum weight for a given length, is best.
     
  2. Van Callum
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    Van Callum Junior Member

    Thanks so much for your feedback, could you indicate me any bibliography or paper which is about this ratio or related with?
     
  3. Van Callum
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    Van Callum Junior Member

    Thanks for the graph, could you share the name of the paper or article where that graph comes from?
     
  4. Ad Hoc
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    Ad Hoc Naval Architect

    Hadler, J.B., E.N. Hubble, R.G. Allen, and D.L. Blount. “Planning Hull Feasibility Model—Its Role in Improving Patrol Craft Design,” RINA Symposium, 1978.
     
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  5. Van Callum
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    Van Callum Junior Member

    And despite of this aspects of the ratio, how can I connect this or other parameter to the power estimation?
     
  6. TANSL
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    TANSL Senior Member

    Thanks Ad Hoc, a topic of great interest. Any studies or articles on this topic, developed with current technologies, something more up-to-date? Thank you.
     
  7. Ad Hoc
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    Ad Hoc Naval Architect

    That's where you need to start to learn the subject, and one liners will no longer provide you with what you seek.
    It is not a 5 second search on Google...you need to read, a lot.

    Not sure what you mean by 'current technologies'...?
     
  8. Van Callum
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    Van Callum Junior Member

    @Ad Hoc Do you know where this image comes from? It's about the effect of the hulls

    upload_2025-3-26_9-28-15.png
     
  9. TANSL
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    TANSL Senior Member

    Exactly the same as you... I suppose. In any case, to be clear, some study that isn't 40 years old. Thanks, again.
     
  10. Ad Hoc
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    Ad Hoc Naval Architect

    Last edited: Mar 26, 2025
  11. Van Callum
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    Van Callum Junior Member

    Thanks so much for your time.
     

  12. TANSL
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    TANSL Senior Member

    How easy it is to become obsolete! You stop reading, you stop learning, and science overtakes you in an instant.
     
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