modern retractable dagger keels

Discussion in 'Boat Design' started by peter radclyffe, Jul 7, 2012.

  1. peter radclyffe
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    peter radclyffe Senior Member

    can anyone tell me anything about them, thank you
     
  2. rwatson
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    rwatson Senior Member

    Whats the difference between "modern" retractable dagger keels and "old fashioned" retractable dagger keels in your book ?

    After 1900 or after 1990 etc ?
     
  3. peter radclyffe
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    peter radclyffe Senior Member

    well maybe hydraulics and the materials R W,they may not be that different, but i would like to know about the old and the new, what do boats like hetairos use, thanks
     
  4. Tad
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    Tad Boat Designer

    Here's the top of Hetairos board, the boom has to be off to one side to raise it all the way. Lifting is done with hydraulic rams. There's a huge ballast bulb on the bottom that got a bit banged up when they went aground in the St. Barths Bucket, she's in some yard getting that fixed now.......

    hell 2.jpg
     
  5. peter radclyffe
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    peter radclyffe Senior Member

    thanks Tad,but who designs these keels
     
  6. Tad
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    Tad Boat Designer

    Ha!....A cast of thousands......If you mean who decides this will be so? The owner says "the boat will have a lifting board with bulb" and by god the boat will have it..........

    In this case the designer's, Reichel/Pugh, will optimize the shape and geometry of foil and bulb, probably with a wind tunnel test program and consulting hydrodynamics specialists.....probably with CFD sub-contractors as well.

    Then a consulting engineering firm will design the structure, and a specialist hydraulics firm will design the lifting system, and they'll be built by separate firms who both have in-house engineers who will start a fight with the original engineers.....then the project manager has to step in and hire another engineer to judge who is wrong.......

    Big boats are fun.........
     
  7. peter radclyffe
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    peter radclyffe Senior Member

    yes,has anyone on this forum designed one
     
  8. quequen
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    quequen Senior Member

    I designed some lifting bulb keels many years ago. Unfortunately, nobody wanted to invest in them at that time, "it won't work" they said. Three years after that, Bill Dixon put an incredibly similar design on "Liara" (100ft). I would have liked it to be a copy of mine, but it wasn't at all. (I think mine was better...:p)
    The good part is that mr. Dixon proved the idea was good and very useful, so my designs (still there, waiting) could be useful too.

    Anyway, this is off the thread: just put "lifting keel" on google, some of the links will redirect you to other places of this forum, there are many builders and designers. Check also for the google image search, there are many "really big" lifting keels.
    One of them, a Philipe Briand design:
    http://www.kaweraueng.co.nz/page/keels-liftingkeels
    another:
    http://www.femstrutture.com/products/Chiglia_Keel/lifting-keel.html
    http://www.apm-keels.com/
     
  9. peter radclyffe
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    peter radclyffe Senior Member

    thanks quequen
     
  10. Tad
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    Tad Boat Designer

    I had a hand in one for this boat....launched 1991......

    BKSophie.jpg

    Sophiesm.jpg
     
  11. quequen
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    quequen Senior Member

    Whow! gorgeous boat. The original Hetarios was a Bruce King design also, reichel and pugh modified it more recently? isn't it? I wonder how they keep all that wood so perfect.
    I didn't mean the lifting keel was an original idea, thought there must be others even early. Mr. Dixon's design has some details I consider originals, he received an award for that and that's why I mentioned him.
     
  12. Tad
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    Tad Boat Designer

    AFAIK there have been 3 boats called Hetairos so far. The first was a 65' aluminum ketch designed by Henry Scheel and built by Huisman in 1985. The second a 125' cold-molded ketch designed by myself and others in the Bruce King office, built by Abeking and Rasmussen and launched 1993. The third is a 198' composite ketch designed by Dijkstra and Reichel/Pugh, built at Baltic and launched 2011.

    The 90' bright finished Sophie (above) lives under a full cover most of the time.

    No, nothing in this business is "original", we just keep re-inventing stuff and adapt it to modern technology and materials.....
     
  13. quequen
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    quequen Senior Member


  14. Tad
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    Tad Boat Designer

    The Winch office was brought in so late there wasn't much they could do at that point. I'd working on her for years by then, all the spaces were defined to the millimeter. She is a wooden boat boat built around permanent structural wooden bulkheads. They detailed the joiner work (actually Dick Young did most of it) and established paint lines etc. I never liked all the heavy dark mahogany, especially in the deckhouse. What Rhoades Young have done with the latest Hetairos I like a lot more, lots of white paint......
     
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