Seaworthiness: The Forgotten Factor- C.A Marchaj

Discussion in 'Boat Design' started by Velsia, Sep 13, 2020.

  1. peter radclyffe
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    peter radclyffe Senior Member

    I designed a colin archer type gaff cutter, partly based on velsia
     
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  2. Velsia
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    Velsia Floater

    If you would oblige me, I would be very interested to see that.
     
  3. gonzo
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    gonzo Senior Member

    Not really. Adding weight will require more power to reach the same speed that a properly trimmed boat will need. Trim tabs do not increase draft and wetted surface to the extent added weight does. Also, the dynamic lift of the trim tabs may provide enough lift to decrease wetted surface.
     
  4. leaky
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    leaky Senior Member

    Sure.. you would know the technical term but usually trim tabs are adding inefficiency too, if they are deployed then they are actually angled somewhat "down" and are "dragging". It just happens that the overall affect is net positive.

    I think adding the right weight to the right place may similarly be a net positive.
     
  5. Will Gilmore
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    Will Gilmore Senior Member

    I think by, "adding inefficiency", you mean correcting greater inefficiency.

    Poor trim underway is terribly inefficient.

    -Will (Dragonfly)
     
  6. gonzo
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    gonzo Senior Member

    Properly used trim tabs do not "drag" but provide dynamic lift and less resistance. That means that for the same power, the vessel has increased speed. There is a huge amount of data proving it.
     
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  7. peter radclyffe
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    peter radclyffe Senior Member

  8. peter radclyffe
    Joined: Mar 2009
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    Location: europe

    peter radclyffe Senior Member

  9. peter radclyffe
    Joined: Mar 2009
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    Location: europe

    peter radclyffe Senior Member

  10. peter radclyffe
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    peter radclyffe Senior Member

    a computer distorted image,9 metres
     
  11. peter radclyffe
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    peter radclyffe Senior Member

  12. DogCavalry
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    DogCavalry Senior Member

    Must agree with Gonzo about trim tabs. Boats overall drag is highly dependent on weight. Trim tabs also create drag, but the coefficient of lift is much greater than the coefficient of drag for a properly designed fluid dynamic component. The chief advantage to added weight would be increased moments of inertia.
     
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  13. Velsia
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    Velsia Floater

    Not really adding anything of scientific value here but these in my humble opinion are an excellent example of seaworthiness + seakindliness.



    Loads of videos from this builder (Safe Haven Marine). Nautical ****!
     
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  14. DogCavalry
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    DogCavalry Senior Member

    These are some wonderful boats!
     

  15. bajansailor
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    bajansailor Marine Surveyor

    Another similar boat (but not quite so extreme) is the VSV (very slender vessel) 'Mary Slim'
    https://www.multihullcentre.com/multimarine/past-projects/vsv-mary-slim/

    Mary Slim.jpg

     
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