34th America's Cup: multihulls!

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

  1. SukiSolo
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    SukiSolo Senior Member

    Like many of you here, I have watched this years AC with great interest. These boats may be on the edge (and too expensive) but amazing to watch and fantastic skill from all those involved.
    One thing I did note with interest on the last 2 days was the ENTZ jib size. It is much, much smaller than on the previous days. Now given that the earlier races were still up to 18-19Kn wind speed and the last 2 up to 23Kn why gear down quite so much?. Surely the (much) higher aspect ratio jib from the more medium weather was a big contributor to ETNZ's upwind speed/manouvre small advantage. It looks almost 3 metres lower on the luff, the one used in races 7,8 and 9.
    Even allowing for OTUSA changing foils (I'm sure they have) and other components, I think ETNZ should be using a jib somewhere between the two sizes they have shown us for the wind strength 17-24Kn. Might be wrong but haven't seen any other mention of this anywhere. I would not be surprised to see a new jib IF the wind speed stays in the same upper end of wind range.
     
  2. petereng
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    petereng Senior Member

    Hi daiquiri - this is why we get thrombosis if we sit down for long periods eg long flights. The heart cannot raise the blood up from our legs. We have to walk around a bit to swish it upward. Peter
     
  3. elliott
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    elliott Junior Member

    Now about these grinders - they are delivering serious loads of energy - but it is totally unnecessary. Outside my window there's a seagull with a wingspan of about a metre riding the updraughts without a trace of fatigue. His wings are balanced about the joint and he sheets in and out by moving his tail up and down. My catamaran's rudders are well balanced which gives me fingertip steering but I have old fashioned soft sails which are a pain to sheet in - I would love a proper wing.

    I whinged about the course on this forum several months ago - I am glad others are of the same opinion but it will be years before rule makers/course setters see the light.

    Good luck to all real multihullers.



    What I cannot understand is why the bored people haven't got anything else to do. For me this has been utterly fabulous racing and I have re-watched many of the races.
     
  4. Blackburn
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    Blackburn Senior Member

    The jib's main job on these boats is to help in the tacks, and the argument in favor of a lower aspect jib is perhaps that it disturbs the upper parts of the wing less.

    Stop me Coxcreek! Before I start reminiscing about handkerchief jibs and near una rigs on the late F40's à la Smyth...

    lol

    -----

    I've resorted to reading AC articles in mainstream papers today; thought it might be interesting to see if Larry Ellison's AC34 could finally get some good press!

    Before I give a summary of how that looked, let me mention something else. The Los Angeles Times has a review of the Top Tech Flops of 2013. Here they are:

    Google's Chromebook Pixel Internet-dependent laptop

    The BlackBerry Z10 smartphone

    The HTC First, a.k.a. Facebook Phone

    The Twitter #Music app

    Microsoft Surface RT tablet

    Nintendo Wii U console

    YouTube on Windows Phone


    LINK

    ... Now I know what you recidivist monohull sailors are thinking! That you have to include the AC72 at the top of that list!

    Am I right? lol

    But I disagree. The AC72 has at long last had a chance to dazzle in some close racing the past weekend, and nobody who really understands the sport can have avoided being very impressed by it. Just a little bit!

    These powerhouses of the modern age - Google, Blackberry/RIM, HTC, Facebook, Twitter, Microsoft, and Nintendo - have all done great bellyflops with the above products this year; While Larry Ellison has on the other hand come along with his little AC34 hi-tech startup and accomplished something amazing, of a Herculean nature: He's got Gary Jobson and Bruno Troublé, and even Ben Ainslie making nice noises about winged, foiling, tightly matched, big catamarans, and conceding that their long-held preference for state-of-the-art monohulls is comparatively uninteresting.

    :cool:
     
  5. Blackburn
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    Blackburn Senior Member

    Here's a Gilles Martin Raget helicopter shot that I liked. Swiped it from Martin Vanzulli's Catsailingnews.com.

    This is apparently Glenn Ashby to windward on the wheel. Looks just as if he was hull-flying for fun on a beachcat, huh?

    AC34TNZFlip4Glenn2.jpg
     
  6. Blackburn
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    Blackburn Senior Member

    All the news that's fit to print!

    Here's a good mainstream press article in the New York Times, of all places.

    Excerpts (my bold):

    -----

    The New York Times also has this 'interactive graphics' item about the AC72's.
     
  7. RHough
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    RHough Retro Dude

    I am of the opposite opinion. Some very clever people looked at speeds, RRS, safety, and fit for spectators when they designed these courses. They tested the concept in the ACWS and fine tuned systems.

    The courses make it easier to pass or harder to defend a lead becuase the gates give an option to split each leg.

    The start line bias is extremely clever. The pin end is shorter on a slower sailing angle, the boat end longer on a faster angle. This gives most of the tactical options of an upwind start while eliminating 50-60 knot closing speeds and opposite tack potential collisions. Darn elegant IMO

    If there is a flaw it is leg 4. With a starboard rounding to a blast reach finish first to the starboard gybe lay line has pretty much won the race. That would be better if they called a port rounding at mark 4 and place the finish line on the other side of the course.

    There were a couple of AC45 races where there was passing in the last leg, but it was very rare. Leg 5 uses the Start/Leg 1/Mark 1 logic in reverse. The windward (slower angle) end of the finish line should be the same sailing time as the leeward (faster angle) end. In theory the boat that can win the start to mark 1 drag race could also come from 1-2 seconds behind and win the mark 4 to finish drag race.

    The courses get a thumbs up from me. :)
     
  8. Blackburn
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    Blackburn Senior Member

    ...

    I was pleasantly surprised that the New York Times had a reporter who could write that well about a boat race! Maybe there's still hope for the Grey Lady.

    At the Los Angeles Times they sent their reporter who had most often ridden on Disneyland's Pirates of the Caribbean.

    ...How can anyone find to write the words 'more pedestrian boats'?


     
  9. Blackburn
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    Blackburn Senior Member

    ...

    Here is the America's Cup herself... driven to desperation by the legions of people who are now calling for her to become a handy trophy for a new inexpensive one-design class...


    NO! DON"T JUMP!!!

    lol

    [​IMG]
     
  10. Blackburn
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    Blackburn Senior Member

    ...

    Meanwhile, back in San Francisco, this is what passes both as journalism and humor. Strange that all these excellent plans (see below) didn't get public funding.



     
  11. SukiSolo
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    SukiSolo Senior Member

    Quote from Blackburn

    'The jib's main job on these boats is to help in the tacks, and the argument in favor of a lower aspect jib is perhaps that it disturbs the upper parts of the wing less.'

    That is part of my point, the smaller jib seems to have made ETNZ a little less handy, tacking. Hence the mention of manouvre upwind. Whilst the main wing has an optimal leading edge a small help from the jibs venturi will make a minor difference even at the high apparent wind speeds. It was just an observation, one I find interesting. I double checked the video of earlier races and it really is quite marked. I'm no expert on multis or rigid wings, far from it but I have played with real world size mast profiles for little sailboats. Good fun and not hard to prototype in short lengths but still 3D enough. Still I suspect these AC72s' are to some degree just large prototypes and a hell of a lot will be learned from them.

    It may be as in the case with ETNZ V LR that the jib is not very significant. These beasts are so close that any small change may well help/hinder them. Learning on the job I believe it's called :)
     
  12. philSweet
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    philSweet Senior Member

    Another aspect that differs between bikes and grinders is the stored energy. A bicycle is nothing but stored kinetic energy. That's what gets the cyclist over top dead center on the pedals. A trained cyclist can pedal around the circle pretty effectively only over a fairly small rpm and load range. A pedal pump would need the equivalent of and egg gear or would need to have a sophisticated cam and pressure driven swashplate on the hydraulic pump, and this would have a pretty big effect on the pump's efficiency. As a guy with a biking build, it's difficult for me to relate to what the arm grinders can do. I had to work an arm bike for physical therapy for a while, and it was horrible.

    The grinders on the AC72's do not appear to have the sort of infinitely variable gearing that permits max power. Not hard to do. Is there a rule?
     
  13. daiquiri
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    daiquiri Engineering and Design

    I have finally had some free time (it was a frenetic Monday!) to see the replay of the last two races and have really enjoyed the race n.10. The two boat's characteristics appear to have come pretty close to each other, which is a good thing for the event. For the first time in this AC there was some intense action, and the race 10 was dominated and decided by race tactics (in good and in bad for the Oracle), finally.

    There were a couple of definitely insane and dangerous moments, when two boats crossed each other's paths at roughly 70 kts relative speed. I didn't believe the crews would take that risk but, hey, they're did it and from the couch-potato's point of view it was definitely some spectacular action. The closer we are getting to the final races the more risks are being taken by both teams, in order to gain or to maintain the leading edge. While it is a really great spectacle for the viewer, I hope it will all end well and without incidents.

    Leo, I agree that the race 9 was not the most brilliant one, but the race 10 was definitely tense and undecided up to the Oracle's bad decision to tack and not follow the ETNZ near the end of the leg n.4. So that one definitely cannot be called a boring race. :)

    Cheers
     
  14. catsketcher
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    catsketcher Senior Member

    In the 1977 Swedish 12 metre challenge Pelle Petterson put pedal winches on their challenger Sverige. They did not seem to be able get the same explosive power as hand winches as they were discarded when Sverige turned up in the next challenge in 1980.

    Phil Weld also tried pedal power in Rogue Wave (or Moxie) but took it back off when he found it was harder than normal winching.

    As for the seagull and winching - the seagull can alter its wing in a few different ways compared to the AC72. They have only one element whereas the AC 72 has 2 elements. The pivot is aft of the front edge of the 1st element but adjusting the camber can't use this principle as the pivot of the second element is far behind the mast pivot.

    On top of that you have to take into account the square cube rule. A seagull weighs about 1 kilo and the AC 72 8000 times more with crew. So the AC 72 will need a lot more power as it is in much stronger wind than the apparent on a seagull and is 8000 times heavier.

    cheers

    Phil
     

  15. Leo Lazauskas
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    Leo Lazauskas Senior Member

    At least there was one that was interesting! I remember there being some
    absolutely awful entire regattas where there were nothing but processions.

    If NZ$ win one of the next two races it will be at a cliff-hanger stage where
    one mistake could decide the AC.
    (More likely is that the wives of the sailors will say it's too windy and they
    will have to stay home and do some yard work, and maybe put up that spice
    rack like they promised to do 6 months ago).
     
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