34th America's Cup: multihulls!

Discussion in 'Multihulls' started by Doug Lord, Sep 13, 2010.

  1. Doug Lord
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    Doug Lord Flight Ready

    34th AC "Race" One

    Works ok for me-thats too bad-why would they block their own country?

    UPDATE-posted below instead of previous page----
     
  2. Doug Lord
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    Doug Lord Flight Ready

  3. Doug Lord
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    Doug Lord Flight Ready

  4. powerabout
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    powerabout Senior Member

    I just dont get what part of the boat is state of the art
    its like trying to make a Moth foil with half the parts missing
     
  5. Doug Lord
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    Doug Lord Flight Ready

    34th AC

    ========
    I'd say you need to read more about this stuff. Prior to TNZ demonstrating a three foil configuration with a single main foil, catamarans were almost always slower on hydrofoils than the same boat sailing without them. The C Class "off your Rocker" was the most recent example.
    Besides the three foil configuration with a single main foil, TNZ "invented" the "curved + "L" " foil which produced an altitude control system similar to a traditional surface piercing foil but with a more limited range: if the speed increased beyond the design range or fell below the designed range the angle of incidence of the foil has to be manualy(electro-hydraulically on a 72) adjusted for the next appropriate range. This design minimized the frequency of daggerboard rake adjustment while keeping the center of lift further outboard than a traditional surface piercing foil. Further, the advantages of a curved foil was maintained so that the angle of incidence of the curved portion of the foil could be adjusted independently of the lateral resistance portion of the foil.
    Believe me, this foil configuration and foil design is the single most significant development in this AC so far and a major breakthru in foil configuration and design for catamarans.
    Two or three C CLass cats have adopted this system* as well as smaller test boats for Hydros and Groupama(Flying Phantom). So far the Flying Phantom, the Hydros F20c test boat and the Hydros C Class cat have all shown high efficiency in terms of speed compared to multiples of windspeed-approaching 3 which is equal to or better than a Moth! This is the first time in history that foiling cats have been significantly faster than their non foiling counterparts.
    It's a big deal.

    * The smaller boats use variations of the foils with greater ranges requiring little to no manual adjustment
     
  6. CT 249
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    CT 249 Senior Member

    Sorry, can't see that there's anything wrong in defending the sailing preferences and general morality of people, especially people one knows and likes.

    I don't agree that the UK and American boats were boring. They were doing some very interesting stuff in the "mainstream" races; Mouse of Malham, Sopranino and the entire JOG and MORC movements, Quarto, Santa Cruz boats, Hoots Mon, Lapworth and Calkins designs, Red Rooster, Windward Passage, Ganbare, Animal Farm, and sailing European boats like the VDS designs that inspired Spencer, the Listang (a light fractional world 1/4T champ years before 45 South arrived) etc.

    And all of those were being sailed at a time when they were also creating one hell of a lot of modern sailing - shorthanded events, round the world races, SMODs, the modern inshore and offshore cat, trimarans, speed trials, foilers, windsurfers, wing masts, wing sails, modern sailcloths, modern construction, etc etc etc.

    Given the number and novelty of the things the Brits and Americans did, both in the "mainstream" and 'fringe' events, the repeated criticism of them as conservatives etc seems completely off base.

    I own some Kiwi designs myself and NZ designers of the time were fantastic, but the amount of criticism hurled by some people at other countries is over the top.
     
  7. Ad Hoc
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    Ad Hoc Naval Architect

    So, from all this reading you have done Doug, can then supply the references for these claims that you are also supporting.
     
  8. Doug Lord
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    Doug Lord Flight Ready

    ================
    I can and much of it is in this thread. The most recent example of a sailing catamaran foiler not being competitive with its displacement sister is included
    in the PDF below. As to the speed claims for three foil(single main foil catamaran foilers) read( and watch) page 3 & 4 of the 2013 LAC thread in this forum. http://www.boatdesign.net/forums/multihulls/little-americas-cup-uk-2013-a-37972-3.html
    And you can find more examples with some research.......


    Attachment-Steve Killings(Canadian C CLass designer then and now) analysis of "off your rocker" toward the end of the document below.
     

    Attached Files:

  9. Doug Lord
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    Doug Lord Flight Ready

  10. Doug Lord
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    Doug Lord Flight Ready

    34th AC

    From Scuttlebutt tonight-

    America’s Cup Conspiracy Debunked?
    Published on July 7th, 2013 | by Editor

    The conspiracy theorists believed the AC72 rule changes presented by America’s Cup Regatta Director Iain Murray were made to accommodate non-class legal rudders being trialed by the Oracle Team USA defense team.

    So Scuttlebutt asked the defender regarding their alleged illegal rudder design. Specifically, we asked if the rudder design was in use prior to the release of the safety recommendations, and if so, why was it since it was not class legal at that time.

    Here was the reply by team manager Grant Simmer: “Oracle Team USA started building two sets of rudder wings on June 1 which were designed based on the Regatta Director’s safety recommendations issued on May 22. These are the rudder wings used on our boats now, and they are symmetric in accordance with the recommendations.” emphasis dl
     
  11. Ad Hoc
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    Ad Hoc Naval Architect

    Sorry Doug, this is not “fact” that support your claims. It is an interesting paper, but it is not an independent peer reviewed paper. It is just a paper that ran two boats, one with a foil one without., that is all. It does not explore the why’s or the how’s it does not explore the limitations, if any, it does not address the differences between the two SORs etc etc. The method of measurements not shown or provided the fact everything is reduced to just sea trials (which is difficult to control known input parameters for proper objective comparisons) means less evidence for correlation etc and even such conclusions etc. The fact that hulls are identical is misleading. The hull shape does not lend itself to foiling, it is created for min WSA min drag in displacement mode, which is very different from creating additional lift for foiling. You would never take a known existing displacement hull and then simply add foils and expect a major difference...certainly not without any quantitative research, which they did not do.

    It is just a paper that uses a sample of 2, only 2, and showed what happened in their small limited set of parameters, with no verified results being presented other than a polar plot. It is most certainly not a carte blanche statement for all boats, not by a long shot.

    The other “facts” you have presented in this thread are all of a similar vein. These are not independently verified facts Doug. It is just someone doing XX and saying isn’t this great.

    So, again I ask you, with so much reading you have done to make such bold claims, please provide me with independent peer reviewed facts.
     
  12. Doug Lord
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    Doug Lord Flight Ready

    34th AC

    =====================
    I disagree with you Mr. Hoc. The facts I have presented are accepted in high performance catamaran design-Steve Killing is one of the most respected C Class designers. Your estimation of his work is way off base as is your assertion as to which type of hull one would add foils to in the C Class. And the performance of the three foil boats speaks for itself whether or not you consider it valid.
    The history of the performance of sailing catamarans with and without foils is well documented-the TNZ foil system is, without a doubt, a breakthru in foiling catamaran design. As are the three foil variations of the TNZ pioneered systems being used in the C Class now and on smaller boats like the Flying Phantom and F20c modified by Hydros. It is an undeniable fact, if the information from Hydros(C Class and F20c), Groupama and Steve Killing is regarded as reliable, that the boats using the three foil system are faster than was was considered "normal" in the C class at the time Alpha was designed.
    When Alpha and Rocker were built and sailed, "normal" C Class performance was considered to be 1.3-1.6 times windspeed.
    1) Hydros C Class in the last few weeks: 2.6-2.83 times windspeed.
    Other three foil test boats:
    1) Hydros F20c-32 knots peak speed
    2) Flying Phantom(Groupama test boat-based on modified F 18-standard hulls)
    ---peak speed 26.4 knots
    --- 2.3-2.9 times windspeed
     
  13. Ad Hoc
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    Ad Hoc Naval Architect

    Doug

    All you are demonstrating is your preference for subjective papers rather than independent papers. This has nothing to do with an authors respect or otherwise. Does the paper outline a set of parameters…no. Does the paper outline variables that were tested….no…does the paper demonstrate the effects of different hulls shape..no. I could go on.

    The paper is just an empirical paper written by someone who found something new to them. That is all. Any supposition and conjecture from this is of your own making and is not supported by any independent verifiable facts. It is a simple as that.

    One does not have a “result” and tailor the experiment to get the desired result and say Viola!! . That is not science. It is salesmanship. Respect is not a scientific term and does not determine whether a paper is excellent to one that is used for fish and chips wrapper. Scientific rigour is devoid of emotions and subjectivity. Both of which you are using to support your claims, ergo, it is an opinion, not a fact.

    PS...Just for some clarity for you. See the attached paper as a crude example. It is attempting to ask questions, the how's and the why's. Their conclusions are also particularly telling. Somewhat different in "tone" to that which you have presented.
     

    Attached Files:

  14. groper
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    groper Senior Member

    Another meaning, without distorting the truth in any way, reads as "...These are the rudder wings used on our boats now, and they are symmetric in accordance with the recommendations, but are illegal in accordance with the original, 3year old design rule which still stands."

    Back to you doug, and youve still managed to avoid my question twice now - What are the performance reasons - as quoted by Ian Murray - that ETNZ and LR are refusing to agree upon with regard to the rule changes?
     

  15. Gary Baigent
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    Gary Baigent Senior Member

    Doing a slight bit of spin there, CT; the reference from Light Brigade to boring Northern Hemisphere designs is to an earlier period, meaning the mid to late 1950's, early '60's, and of your list only a few comply to the referred time. Also there were later acknowledgments to the exceptions like Van de Stadt's Black Soo and others.
    But how about this quote, in Light Brigade, from Olympic medalist Peter Mander ... "the Northern Hemisphere influence amongst sailors here is minimal and the reason multitudes of overseas dinghy designs are not here is because they are duller than comparable craft sailing in NZ."
    He was referring to dinghies, and smaller craft have always been development years ahead of larger yachts.
     
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