proa rigs

Discussion in 'Multihulls' started by Alex.A, Oct 2, 2010.

  1. Alex.A
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    Alex.A Senior Member

    Too true.... But i have time now - my local dam has run out of water!!!:mad:
    And no rain for ages:(
     
  2. whirlwind
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    whirlwind Junior Member

    Flettner Rotor IS A SAIL

    the rotor absolutely is a sail. No wind , nothing happens no matter how fast you spin the rotor. Only when wind acts upon the rotor to induce the Magnus effect will any thrust be generated - Just like any other sail :cool:
     
  3. basil
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    basil Senior Member

    Check out Proafile http://proafile.com/multihull-boats/ The Gibbons rig seems to be able to address the issues of (simple?) rig movements for each change of direction. On the front page they also address the advantages of the Marconi rig.
     
  4. Clarkey
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    Clarkey Senior Member

    I would be interested to see some data supporting that statement....
     
  5. whirlwind
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    whirlwind Junior Member

    CLARKEY, you are very right to question the validity of the DarthCluin, statement.
    In fact the ship was very efficient
    She achieved her "under power"speed using the installed 160 hp motor driving a 3 blade prop.
    However she reached the same speed using only her rotors ( sailing with her prop free wheeling and the main engine switched off) which were powered by a single 46 hp Krupp generator which supplied both the rotation motors ( 15 hp krupp eletric motor)
    Even if she were to require all available 30 hp ( which Flettner said he never did in his book) that would
    make her 5 times more efficient than under her diesel alone.

    The lesson for DarthCluin, is do your research and don't just regurgitate wiki- mistakes.
     
  6. DarthCluin
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    DarthCluin Senior Member

  7. Clarkey
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    Clarkey Senior Member

    I believe that Whirlwind was using the Flettner rotor ship 'Buckau' as an example.

    If you have any data regarding the 'Unikat' proa I would be interested since I don't think the paper is yet freely avaiable online.
     
  8. whirlwind
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    whirlwind Junior Member

    uniKat

    I believe the report on UniKat is In the library at the University of Flensberg.
    I do not think they published a public version.
    However I can see the logic behind their thinking. A vessel which can sail in both directions with the apparent wind on the same side AND a sail that can produce thrust in both directions controlled by the flick of a switch to change rotation, makes perfect sense.
    There is some video on YouTube of UniKat sailing and it us impressively fast.
     
  9. DarthCluin
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    DarthCluin Senior Member

    Nowhere in his post does whirlwind mention "Buckau".
    Nowhere in his post does whirlwind reference the source of his information.

    If the Wikipedia article is in error, you can correct it, and you have an obligation to do so.
     
  10. Clarkey
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    Clarkey Senior Member

    I have never said that the Wikipedia article is in error, neither would I be under any obligation to correct it if it was. I simply asked if you had data that supports your claim:

    "Sadly, it is not as efficient as using the same motor to turn a propeller to push water."
     
  11. whirlwind
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    whirlwind Junior Member

  12. DarthCluin
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    DarthCluin Senior Member

    Clarkey I was responding to whirlwind, who did say the Wikipedia article was in error, and added:

    "The lesson for DarthCluin, is do your research and don't just regurgitate wiki- mistakes. "

    Looking something up on Wikipedia is research. Posting the link to the article is corroboration. Refuting someone else's research without corroboration is opinion.

    Wikipedia articles can be edited by anyone. If whirlwind knows the Wikipedia article is wrong, he has the ability to fix it. Is he obligated to fix it? Perhaps not, but he should have provided links to the information that refutes it.

    I posted those links in October of 2010. If his information dates after that, I would like to know the protocol for accessing web pages written in the future.
     
  13. whirlwind
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    whirlwind Junior Member

    DarthCluin, Quite right , I did not mention BAchau in my reply. I should have.

    However the quotation you posted from Wikipedia is directly in reference to Bachau and so I felt we were all on the same page.

    Here is the source of my information.
    http://flettner-rotor.de/geschichte/buckau

    Bing does a good job of translating if your German is rusty.
    See below:
    http://www.microsofttranslator.com/...&a=http://flettner-rotor.de/geschichte/buckau

    You will see that all I have described earlier is correct.

    I will go to Wiki and attempt to correct their obvious error.
     
  14. Clarkey
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    Clarkey Senior Member

    There seem to be some crossed wires here. The Wiki page you linked to does not contain the assertion:

    "Sadly, it is not as efficient as using the same motor to turn a propeller to push water"

    I was wondering why you were making that claim and asking if it was derived from any data in particular.

    Drifting back towards the topic, Flettner rotors make interesting proa rigs because they suit vessels that don't come head to wind.
     

  15. whirlwind
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    whirlwind Junior Member

    rotor wind

    CLARKEY
    I often thought it would be interesting to watch a wind sock as the wind went from apparent on one tack to true wind as the boat stopped and the apparent on the other. Most of all if the keel line stayed in the same orientation.
    The rotor would also act as a break to slow the boat as soon as the direction of rotation was changed so the reversal could be very quick indeed
     
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