Daggerboards On Power Catamaran?

Discussion in 'Powerboats' started by GalenP, Jan 5, 2013.

  1. GalenP
    Joined: Dec 2012
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    GalenP Junior Member

    How come we don't see any daggerboards on power catamarans? If you had a lower powered displacement catamaran, wouldn't it be more fuel efficient with the wind on the beam or quarter to have a daggerboard? And wouldn't turning performance increase at slow speeds for docking?
     
  2. Ike
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    Ike Senior Member

    too much drag. Too much draft. They length of the keel on each hull provides enough lateral resistance and keeps the boat running in a straight line. There is no real need for them.
     
  3. longcours62
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    longcours62 Junior Member

  4. GalenP
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    GalenP Junior Member

  5. GalenP
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    GalenP Junior Member

    Well I am thinking a powercat designed with daggerboards would not have keels. The draft is not really an issue because you can pull them up. Your draft would actually be less.

    The drag though is the main question. Although again, keels also produce drag, and daggerboards with their better foil shapes tend to be more efficient than keels on a sailboat. Maybe power boaters just don't want to deal with them?
     
  6. longcours62
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    longcours62 Junior Member

    Unfortunatly I have not photo of them expet on this photo the black part on the passageway before paint and put in place .http://long-cours.62.over-blog.com/photo-1917001-23-02-2009-15-22-30_JPG.html
    They are asymmetric, in ply wood with fiberglass and epoxy.
    3,2 m lenght and when down we have a draft around 1,60 m.
    But of course could be make in better, lighter and expansive materials...
    And on the photo of this page you can see one just behind the door of the wheelhouse in is upper position
    http://long-cours.62.over-blog.com/article-derives-100689323.html
     
  7. GalenP
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    GalenP Junior Member

    longcours62 - Thank you. And is the boat more fuel efficient with them down with the wind on the beam? I assume you pull them up going downwind?
     
  8. longcours62
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    longcours62 Junior Member

    For example if we receive wind on starboard , we put the portside daggerboard down, and after that the boat going up few ° and after stabilise the ruder angle , for keept the course became far smaller (sorry for my english !!)
    But for said if it make a better fuel efficiency,? I hoppe so but it is difficult to make the ratio betwen : drag of board and less rudder angle+less drift
    But I think it is better because ruder whit angle it is a big brake, and the flow aroud the hull it is better if the "drift" is smaller
     
  9. Frosty

    Frosty Previous Member

    If your under power whats the problem.
     
  10. GalenP
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    GalenP Junior Member

    For me it's a question of efficiency of power. If you have a very high power boat than this idea is not very relevant. But if you are looking at very low power but highly efficient displacement hull, then the question may be relevant.

    I imagine this is a question that a sailing catamaran under power could answer very easily. Boards down or up when motoring with the wind on the beam? Which is more efficient fuel wise? But the sail rigging has a lot of wind drag, so it may not really answer the question.
     
  11. GalenP
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    GalenP Junior Member

    Interesting and thank you. And for a multihull that probably weights less and draws less than your boat to start it would probably work even better.
     

  12. 805gregg
    Joined: Apr 2010
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    805gregg Junior Member

    I agree, it will just slow you down, if you are under power, the engine and rudders control where you head, there is not much lee way to deal with. It may help with rolling on a mono hull but, not a cat.
     
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