Lateral centre of effort

Discussion in 'Powerboats' started by gtflash, Feb 13, 2010.

  1. gtflash
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    gtflash Senior Member

    I am trying to understand the meaning behind lateral centre of effort and HOW it can be moved fore and aft in a planning boat hull design..
     
  2. CDK
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    CDK retired engineer

    Please define "lateral centre of effort". Is that an existing term or did you just invent it?
     
  3. gtflash
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    gtflash Senior Member

    I dont know, hence why I am asking... I assume it to be similar to center of lateral resistance.... This I loosly understand when applied to a sailing boat, but not in practice on a planning boat.
     
  4. gtflash
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    gtflash Senior Member

  5. Hunter25
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    Hunter25 Senior Member

    Gtflash there is some confusion about your term which is why you are not getting much response. Do you mean center of effort on the sail plan or center of lateral plan on the under water areas or something else? Center of lateral plane is the proper term if discussing under water area. Center of lateral plane and center of lateral resistance are interchangeable in common discussion and represents the center of under water areas of a hull.
     
  6. jehardiman
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    jehardiman Senior Member

    To set the terms for a sailboat..

    The Center of Effort is the point in the rig (not necessairly on centerline) that the sum of all the aerodynamic forces are resolved into a single force vector (with no moment) that acts to drive the boat forward (or not as the case may be). This single force vector broken down into two perpendicular vectors, the Driving Force in the direction of travel and the Heeling Force transverse to the direction of travel (note these are NOT along and transverse the CL of the boat).

    The Center of Lateral Resistance is the point, on Centerline below the waterline, that the sum of all hydrodynamic forces act through when resolved into a single force vector with no moment. Again, this single force vector is broken down into two perpendicular vectors, the Resistance and the Side Force. And again these forces are referenced to the direction of travel, not the boats centerline.

    Now gtflash, this is how I understand your question: How do you manipulate the Center of Lateral Resistance, the Resistance, and the Side Force on a planning boat?
    Well, then we need to clarify the question further... upwind or downwind, centerboarder or not?
     
  7. gtflash
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    gtflash Senior Member

    Thanks fpr replys. Sorry for confusion, I am quoting something written to me, we were discussing high speed craft and hooking.

    " The lateral centre of effort – it is similar to the centre of lift on a wing or sail – should not be forward of the longitudinal centre of gravity (lcg) position. The idea is that when the hull is yawed to the direction of motion the side force created is aft of the lcg so the lever tries to straighten the boat up rather than spin it on round which would happen if the side force was ahead of the lcg."
     

  8. jehardiman
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    jehardiman Senior Member

    Controlling the directional stability is a little bit different between power and sail and upwind or downwind. Hooking may have more to do with wave conditions in a vessel with marginal directional stability, especially a power boat were the drag is all wetted surface.
     
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