34th America's Cup: multihulls!

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

  1. RHough
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    RHough Retro Dude

    I made that remark for the obvious reasons. There has been so much made of the nationality of the sailors (not mentioned in the Deed) and so little about the nationality of the boats. The AC was gifted to promote competition between *boats* constructed (designed and built) in foreign countries. Not for competition between crews constructed (conceived and born?) in foreign countries.

    Other than the graphics, how is one to tell the nationality of the boats? One is very clearly Emirates, the other very clearly USA. ;)

    The subject is very emotional for many and it is all to easy to wind people up about "nationality" like you can tell where someone was born from their dna.

    Now we have a new 'scandal' going about the foil controls on USA ... it never ends! :cool:
     
  2. Doug Lord
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    Doug Lord Flight Ready

    First Foiling America's Cup

    ====================
    Unfortunately, the Jury is still out on whether that's possible or not.....your conviction is under review.
     
  3. petereng
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    petereng Senior Member

    Hi - I think that the answer is simple. Simple is best. ETNZ and OUSA started designing AC72's at about the same time. But OUSA actually started designing foiling multis a long time ago for the AC33. In the AC33 they had unlimited technology. They had LIDAR, on board computers, motor energy, everything available. That created a huge pool of concepts and solutions. These were available to the AC72 project (if legal) But at some point of time once the design space was mapped and the possible solutions were identified and the design team got busy, the ultimate possibility level of the design was set in concrete. This too happened in the ETNZ team. So perhaps about 2 years ago the ultimate performance of the boats became a fixed entity. It then became a sailing and logistic timeline to acheive that possibility. ETNZ had no major hickups, no breakages, no team disasters. So they merryily developed and developed and won the LV and had exacly the right momentum for the AC final. But OUSA had disasters, boats, people, cheating. All of these things took time and energy to deal with and took focus away from the AC34 final. So they entered into the final with an immature team and design. This is the ober crux, a team either focuses and overcomes or crumbles and fails. OUSA focused and improved and realised the full potential of their efforts and design. TNZ peaked too early and their design was not quite there. Kudos to OUSA. There are various technical issues like short race times, wind speed limits that went against ETNZ but there were also the race penalty that went against OUSA. There will be lots of books written about this event it has been an epic battle. I had the opportunity to be involved in some of the early Australian Challengers stuff and we coudn't get the money together. So I've had a slightly different view on this event. Its been a great ride. Congrats to OUSA they must be a great team. Peter S
     
  4. Doug Lord
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    Doug Lord Flight Ready

    First Foiling AC

    ==================
    Sal, curiosity has got me: if you can tell-what did you supply to the Team?
     
  5. daiquiri
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    daiquiri Engineering and Design

    Did you try with Mr. Clive Palmer? Since he was apparently able to find the money necessary for building the Titanic 2, want to see that he could find some for the noble cause too...? ;) :D
     
  6. DCockey
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    DCockey Senior Member

    It appears that ETNZ knew about Oracle's "self-leveling system" well in advance of the regatta but believed that it was inferior.

    Gino Morelli was on the ETNZ design team. In an interview with Morelli which was published on September 3 Morelli said (emphasis added):
    GM: Oracle have a narrower boat so if we get into displacement sailing, like in 8 knots of wind, they may have a “slippier” hull which may be an advantage if it’s super light. Just watching them sail over the past six to seven weeks you can see that they’re climbing up the learning curve fast. Their daggerboards and control systems have evolved towards ETNZ’s. They have a theoretically better system, but I think they’ve basically thrown in the towel and said, "We can’t seem to make this work, we’re going to have to go to a self-adjusting system, a self-leveling system." So they gave away, I think, one of their potential advantages in a breeze. http://www.sailingworld.com/blogs/racing/americas-cup/writing-the-rule
     
  7. Doug Lord
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    Doug Lord Flight Ready


    ===================
    Kinda comforting to learn that guys like Mr. Morelli can be totally wrong: "So they gave away.........".
     
  8. laukejas
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    laukejas Senior Member

    Hi all, I‘ve been reading this thread for a while, and now when AC is over, I thought I‘ll also state my opinion, a little review, from a position of non-experienced, somewhat understanding sailor. Not that my opinion would matter a lot, but maybe someone will find some interesting thoughts. Maybe not.

    First of all, congratulations to Oracle team USA. While I was rooting for Emirates Team New Zealand (for reasons that have more to do with future of AC than any personal preference), both teams are respectable, and Oracle has performed a miracle, that is truly a sensation in the world of sailing. I can‘t, however, shake off the feeling that the Cup should have ended the day when race was abandoned due to time limit. After that, Oracle eventually progressed well beyond New Zealand‘s abilities in standard conditions, but that day, both teams were forced into unknown, into something that they haven‘t been trained for. I think Dean Barker and the team showed true mastery of seamanship that day. In my opinion, it is these conditions – light, unpredictable wind that show true skill of the sailor or even more – that of the tactician. Rwatson on this forum once said that the light winds are the biggest challenge. Of course, I know that both teams agreed to this 40 minute time limit. I’m not familiar with the backstory, but I guess it didn’t seem an issue at the time, not something to protest against. However, almost everybody now agrees that this time limit is way too short.

    This America’s Cup was one of the greatest. There’s no denying it. What I said before doesn’t change it. It was intense, it was close, it was exhilarating. The comeback of the century. Never ever has the AC been so exciting. But what actually made this one so great to watch, I wonder? I could come down with a list:

    1) Coverage. The whole presentation was astounding, way beyond anything I expected. All the camera angles – from chase boats, from helicopters, from shore, onboard cameras – they made it possible to see everything from spectacular near-capsizes from many angles down to facial expressions of the sailors. It was professional, it was quality, it was presented greatly.
    2) Presentation. Commentators done a great job, they seemed like they really understand what’s going on, and even though most of the time I knew what was happening before they said it, I try to look from a viewpoint of non-knowledgeable sailing enthusiast who loves sailboats in general or just roots for his country, but doesn’t understand a thing – and for such a person, commentators presented everything smoothly, not too-technical, with gradual learning curve, and along with inter-race clips (“Velocity made good”, “Know the game”, and so on), could lift a complete newbie to sailing to a level where he can understand at least something , so he doesn’t have to wonder “why they zigzag all the time?”.
    3) Computer graphics. Laylines, boundaries, windward distance, tidal stream representations, wind shadow, the occasional panels with VMG, TWD and BS helped both amateurs and hooked-on sailors to follow the game, speculate on what are options for both the teams, and even predict what might come next. These were made brilliantly. I still don’t understand how they managed it, but it really helped a lot.
    4) Venue. Although I have much criticism for it (will mention later), it has distinct advantages. Close to shore, close to viewers, very interesting tidal flow which makes strategy crucial, ability to place many cameras and produce before-mentioned computer graphics. There are certainly many good things in this San Francisco venue.
    5) Close racing. This might have more to do with the strength of the teams, but the choice of venue, race course and boats also has major influence, no doubt. No one likes to see one boat far ahead with other one waiting for inevitable second place. While I don’t necessarily agree with the methods on how this was achieved in this AC (meaning rules and regulations, not actions of the teams), I hand my hat for the final result – most intense AC ever.

    However, I might also add some things in general that could weren’t that great, and (in my opinion) could have helped improving this AC, or future AC’s.

    1) First place comes down to the infamous 40 minute time limit. Come on, there is no excuse for that. Even commentators can’t keep themselves from stating on worldwide broadcast that this is plain wrong. How come that with budget of millions of dollars, they couldn’t manage to run a simple computer simulation of average-performance AC72 in 5 knot wind for this course, calculate the time, add 30% error margin just in case, and get on with something like 1.5 hour limit? I mean, what’s the worst that could happen? Both teams losing their wings, and sailors rowing their boast with bare hands to get to the finish? That’s the only case I can imagine to cancel the race because it’s taking frustratingly too long. And these excuses about having to do commercial breaks no more than 40 minutes apart have nothing to do with sport, and are a disgrace to the Cup. Shame, shame, shame.
    2) Wind limit. So many races canceled because of that. I know what happened with Artemis, and I mourn the sailor who died, I understand the impact on AC safety rules, and I respect that. However, in my opinion, the tragic accident shows that there is something wrong with the boat, rather than the 21 knot wind, which isn’t such an end-of-the-world for any seaworthy vessel. However, I see no other option to increase safety here with AC72’s, so I guess for the time being, this was the right (or the only) call. For the next AC, something must be done about this, because it is both frustrating and an insult to the boats which were designed to sail in 5-28 knot range.
    3) Presentation and computer graphics could be more technical and aimed at knowledgeable sailors. While my heart fills with content when I understand that current presentation helps total newbies to come into sailing, I can’t help but feel left overboard when I understand there is no amends for sailors who already know why sailboats zigzag and why going into tidal stream is a bad idea. There are so many things that could make this better. Add wind pressure map to the computer graphics, show possible predictions of both boat tactics (like it’s done in broadcast of sports like pool), comment on things like wing trim and camber, headsail choice (come on, when commentators talk for 5 minutes about it, and still can’t tell a difference between bigger headsail and higher ratio aspect headsail, I wish I was commenting), and so on.
    4) Repeating history and race-informative clips. Enough is enough. I was sure that if I’ll hear that damned phrase one more time, “knowing the game means understanding the rules - an integral part of sailboat racing at ANY level”, (with extreme emphasis on “ANY”) I’m gonna puke. Maybe they didn’t expect to all 19 races to happen, or maybe there were just too many unexpected empty time spots that needed to be filled with something (and how many times can you replay the past races?), but they should made more of those clips. There is so much to tell. On the other hand, I consider – maybe that was done on purpose, so that people who just tuned in could “get on the race” faster? If that is the case, I, as an amateur sailor who regards and respects professionalism, remember the formula of soap-operas: made in a fashion that if you started watching from the middle, you haven’t really missed anything, because everything important is being reminded every 10 minutes, and you’ll get on just fine. This kind of philosophy is degrades the viewers who watched AC from the start, and would rather see and know more, further, deeper, instead of being educated for the 4th time on how to calculate damn VMG with hand calculator.
    5) Hiding the truth. For example, the 2 point deduction to Oracle. When I first realized it (I missed that on AC45’s), I thought – why? Commentators mention again and again, “and due to 2 point deduction for Oracle team USA, they have to get 2 more wins”, etc., never actually explaining why the heck are these points deducted. It wasn’t until the middle of AC that they finally mentioned that “an infraction during AC45 Series” lead to this deduction. What infraction? What did Oracle do? What does this have to do with AC finals? I had to go to Wikipedia and find out about the whole bag of pellets thing. I felt so angry that commentators didn’t explain once why this deduction was made – almost as if they were covering for Oracle, not to disgrace them in front of worldwide audience. But it’s hiding the truth. Oracle were cheating at the time. That is the word. Cheating. They got punished for that (too harshly, by my opinion – what happened in AC45 should stay in AC45, the 2 point deduction really disbalanced the AC finals, and should have never been issued). However, since that deduction was made, reasons should be stated clearly to the audience. As I said, even though Oracle cheated at the time, they paid for their mistake, I think they were punished too harshly, but if that was the decision of umpires or whoever did that – it should be explain, rather than covered in such a despicable way.
    Also, covering of 40 minute time limit. As much as commentators repeatedly reminded of it, it looked as if they were avoiding to explain the reason behind it. Don’t tell me they didn’t know. The question “why is there that time limit?” must have burned through the minds of the audience the whole regatta, and it was never explained. Was it too inglorious to state that this was made to satisfy commercial breaks? If that is the case, I can see only one solution: don’t make regatta rules that are governed by reasons that are a shameful to admit.
    6) Cost of participating in the AC. I know the history, and I know that AC was always a millionaires game, and that the phrase “boat is the hole in the water where you throw money into” applies here like a textbook example, but the fact that only 3 teams could afford to participate in Louis Vuitton Cup, and that only one of these teams had enough finances to make a challenger-worthy boat (not to diminish role of Dean Barker and the team by any means), hints something, doesn’t it? Maybe ambitions went too high. Bigger = better doesn’t always apply (as faster = better also, for that matter). I’m sure something can be done about this. But the attitude “if we had AC72’s this year, it must be AC100 next year!” will eventually kill this sport, as fewer and fewer teams will be able to afford participation. You can also expect more commercials, more advertisement banners on boats (bigger boats have more space for these banners!), more money-influenced rule changes and venue choices, and so on. These things just kill the spirit. Look what happened to F-1. All veteran fans are crying after introduction of bloody KERS – a system designed to increase number of overtakes, because some “smart” guys thought this is the thing that will increase the worldwide interest. Damn commercialists. You probably know what happened next.
    7) Venue. I mentioned its merits earlier, but as you well know when wind changes direction, it is not possible to alter buoys much, and this produces a highly preferable tack, which hurts tactics. Maybe something can be done about this next year, maybe not, I don’t know. Not a major issue, but it stings at times.

    These were the less-controversial things that I personally hope will be overviewed for the next AC. I believe such changes wouldn’t hurt anybody or anything (except for commercials, adds, banners, and cheap tricks to attract audience, but I hate those things, and many other sailors do, so it doesn’t count as hurt).
    Now I’ll make some points about that spirit and whole philosophy of the AC. I expect hate comments, it’s okay – but I hope that someone will find some valid points. I also have almost zero expectations that any of these points will be ever taken in consideration for further AC’s, but still.

    1) Seaworthiness. All right, I’ve seen some dispute about this, and while I agree that AC isn’t about boats that go around Cape Horn and to where no man has been before, seeing these catamarans that can currently race in no more than 21 knots because of wind limit, and no less than ~10 knots because of time limit – reminds me of a flower species named Petunia, which can die for 100 different reasons, first of which being not looked after for a day. Too much sun, too little sun, too much rain, too little rain, too much sun, too little sun, etc. can kill it. I call that plain pathetic. AC72, on the other hand, is top performance sailboat. It resembles the apex of current technology. How can one look with respect at this technological marvel when it can only sail in ~11 knot range? It has very narrow set of conditions in which it can sail without taking forever or breaking apart. It couldn’t survive even a light storm just because it can’t take its wing down. That’s why, for me, it resembles a garden-grown, no – greenhouse-grown plant: it couldn’t survive “out there”. Not even close.
    Remember the old AC boats. Open seas was their domain. Sure, there were also some condition limits, but nothing like this year.
    2) Sail variety. Okay, there is no doubt that wings rule over sails in terms of generating lift, and therefore, boatspeed. But the fact that AC72’s sail more to their apparent wind than to the true wind has limited the necessity of auxiliary sails. Incident in Louis Vuitton when Team New Zealand lost their jib halyard and tossed the poor sail overboard, winning still, shows that the jib doesn’t actually do much except for helping tacks. In AC45 Series we had genoas, at least. In AC72’s, they are no longer needed. The code zero sail has also proven almost useless, as it is hard to foil with it, and everybody wants to foil downwind. The day when Team New Zealand went with code zero, and Oracle stayed with jib, actually proved that in all but the lightest conditions that sail is obsolete. I think that there is no way around this – as long we have wings and foiling, apparent wind direction will be too far forward, and high aspect jibs will be preferable, negating need of other sails.
    Now let me state an alternative. Toss the wing. Toss the foils. Return to the soft-sails. Boat speeds will decrease, sure, but look at what tactical battles would commence. There would be no need for wind limits (except for storms, of course), as mainsail could be reefed (clearly impossible with wing), jibs, staysails, genoas, even spinnakers or gennakers could be raised or lowered to suit different wind conditions. A whole new tactical era would begin. Who chose the right configuration? Who can adapt faster to changing winds? Who can find the sweet spots for their current sail configuration? Who reefed early enough, and who will end up broaching? Sailors could compete in conditions from glassy waters to breaking waves. I would kill to see this in AC.
    3) Aesthetic element. Multihulls, wingsails, foils. They are fast. They have many advantages over past AC boats, the foremost being the speed on both upwind and downwind and close racing. As a sailor with moderate knowledge of sailboat physics, I understand.
    But take an average person who has little or no knowledge of sailing. Say to him – “sailing”, and he will answer – “Sea. Sails. Ropes. Breeze. Waves. Journey.” If he has ever sailed, he might describe the smoothness of wooden deck, people looking towards endless horizon, white sails flapping in the breeze. Something clean. Refreshing. I guess this could be the image of sailing to a person off-the-street.
    Speak out loud the word “sailing”, as you imagine it, and take a look at these two photos:

    http://upload.wikimedia.org/wikipedia/commons/0/0f/Velsheda_solent_(416500624).jpg
    and
    http://2.bp.blogspot.com/-ilNMGMOfL...r2Jj9HNLs/s1600/ETNZFoilsAC72CC120809-605.jpg

    And tell me, which has more resemblance with “sailing”? Now you may say that this has nothing to do with AC, but talking of the “spirit” of this event, I dare to call it more than essential. How far can we go from what traditionally, even romantically can be called sailing, how many elements we associate with it can be taken away before we recognize that we no longer recognize it as such?
    Wide multihulls over sleek monohulls, plane-resembling wings over white flapping sails, foils over hull gracefully parting water… There is much that was sacrificed for the sake of speed. With AC72’s, the real fun is when boats are close , when overtake or covering is taking place, or when somebody is about to capsize. Then it is truly spectacular. Even though races take only around 25-35 minutes (only half an hour, think about it. Old AC’s took several hours a race at least), once one boat is away – I saw many comments stating this on this thread – it soon becomes boring to watch, as the boat behind little chance of catching up.
    The reason to this, I daresay, is that the close racing and near-capsizes is almost the only thing exciting about AC72’s. You soon get used to the sight of foiling, and guys in helmets, sunglasses and rubber costumes running around and squealing as they grind, and that’s about it. I quote Leo Lazauskas, “The Facebook generation are too busy to watch a boat race in which guys bounce around on a trampoline wearing rubber turtle suits.” While that is said quite extreme, I can’t help but see some truth in that phrase. It really could look like that to non-sailor community, which constitutes a part of AC audience, and probably not the lesser part. Sailors, as well as boats, no longer look elegant. It is something you can watch with ardor, but hardly admire as a beauty – at least in traditional image of sailing. Yes, time goes on, things change. I’m just not sure if for the better. Some things shouldn’t be sacrificed, I believe.
    I watched most of AC45 World Series, but only in finals of AC, there were these short clips on short history overviews. I saw, again (and some excerpts that I didn’t see before) moments of 12 meters, J-Class, IACC. I was struck once again – how immensely beautiful these sailboats were. Giant, gracious, looking like they could take a voyage around the world (which isn’t that far from the truth). They looked Seaworthy, in the best possible sense of the word. The boats were beautiful. You could watch for hours as they soared through waters, parting waves with sleek bows, spraying on deck, with their white, breathing sails stretching in the wind, the raising of giant spinnakers, the sailors futzing with lines… Maybe it’s only my preference, but that alone made AC worth watching. There could be only one boat, and still it was breathtaking.

    This was now traded for speed and close racing. AC72’s feels like Formula-1 on water, just missing an engine – like these boats being driven by wind is more like an obsolete limitation than like a natural thing. In other words, everything is so modern in these boats that I can almost articulate a question – “so why the hell do they need wind for such monster?”, even though I dislike motorboats and love sailing in general.
    Was it this change worth it? For some, I guess. Myself, I’m nostalgic for the beauty of the old AC boats. That felt like true sailing.


    As I said before, I have no hope whatsoever that the AC will return to non-foiling monohulls with soft sails. As many people stated in this thread, technology can never go back, and that is true. While I don’t actually think that elements that are sought after today make AC great, nevertheless, this AC was exceptional, exciting and intriguing to watch. I just tend to think that if not for Oracle’s miracle, all this wouldn’t be so true – and these kind of comebacks don’t happen often. In other words, this particular AC was great, but personally, I don’t like the path it’s taking, and I really fear what awaits down that path.

    Thank you for those who red this long review, and for those who hadn’t the patience – I hope you didn’t break mouse wheel scrolling down through :D
    Also, forgive if my English isn’t too good yet. I’m trying real hard.
     
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  9. Remmlinger
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    Remmlinger engineer

    This is for me the first plausible explanation of the miracle that US17 changed from a pitching, unstable boat over night into a vessel that sails steady like running on railway tracks. The question is whether they employed a closed loop controlled hydraulic system for the trimming of the hydrofoils (the emphasis is on "closed loop"). If this was the case, then the Kiwis had no chance at all, it is like fighting with bow and arrow against a machine-gun. A few years ago I designed and developed closed loop hydraulic control systems for race car drivers. These systems react within a few milliseconds, at least 10 times faster, than any human being can do. The question whether the hydraulic power ist constantly supplied by the grinders or stored in an accumulator is irrelevant for the performance of the system. If such a system is allowed, one might ask why TNZ did not have it.
    Uli
     
  10. daiquiri
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    daiquiri Engineering and Design

    Laukejas,
    nice post. You have put a lots of effort in it, and have explained perfectly your point of view. I share a majority of your considerations, in particular the one about the importance of the visual elegance of sailing. I have expressed several of your feelings in the past discussions in this forum. I even wrote this once: http://www.boatdesign.net/forums/sailboats/americas-cup-declining-10664-10.html#post641508 and was proven wrong about the close-quarters combat by few recent races in the finals (the point about limits of foiling transportation remain valid).

    So, yes - I am nostalgic too, and was contrary to the adoption of these boats for the AC. But then I have realized that perhaps I am not nostalgic of those beautiful monohulls, but rather of the old times which they remind me of - which is very different. If you ask a 20-yrs old kid what does he prefer, he will imo indicate a fast foiler. Ask him the same question after 25 years time, and he will likely have changed his preference in the meanwhile, now opting for a more easy-going displacement or semi-planing mono.

    This one is for you, I took that photo a couple of months ago: http://www.boatdesign.net/forums/sailboats/americas-cup-declining-10664-8.html#post641013 . I know you will appreciate. ;)

    That said, I have to say that the wall has been broken and it won't be possible to redo it the old way, in my opinion. The foiling sailboats are now here and will remain here. I believe it would be so even if Kiwis won the AC. Like I said in one of my latest posts, the sailing technology has to move forward, and will. It is a non-avoidable fact.

    At the end, seaworthy vs. unseaworhy, monos vs. multis, foiling vs. planing, rigid wing vs. soft sails - they are all product of decisions and agreements which become class rules of the event. It happened that that it was decided to use foiling cats for this edition of the AC, just like it was decided at some point that cars have to drive in the right lane. Once it became a rule, people got used to it and now it would be pretty difficult to enforce driving in the left lane. After all, we are talking about a very particular sport event (on the borderline of the meaning of the word "sport") which has nothing to do with so many other regattas around the world, in which the other types of sailboats (displacement and planing monos and multis) will continue to have the main role. In the case of the AC, the rules wanted the foiling cats, and that's what we got. Period. The rest is just discussion for the sake of discussion.

    Cheers

    P.S.
    Your English is excellent! Your writing is crystal clear! :)
     
  11. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Sure, but that is also just my personal preference. Other people find interest
    in many other aspects and phases of a race that I find dull.

    Some of what I said was half in jest. It is a big event and, as Jenny Giles
    wrote, there is "trash talk", and laughing at failure and misfortune.
    Nobody should take it too seriously. :)
    If it was a World Cup football game we would be laughing at Italians diving
    in the penalty box, or England missing penalty shots against Germany, etc etc.

    And your written English is really improving quickly, Laukejas.
     
  12. Doug Lord
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    Doug Lord Flight Ready

    34th AC

    ==============
    Thank you very much for your thoughtful comments!
     
  13. Corley
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    Corley epoxy coated

    I don't think that many people would genuinely want the compromises that making the boats truly seaworthy would bring. Better to hold the races inshore and set a tight window of operation. The initial AC72 rule suggested a number of different wing choices for different weather conditions that however didn't end up happening.
     
  14. Doug Lord
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    Doug Lord Flight Ready

    First Foiling America's Cup

    I picked up a little tid bit that Oracles foils had "interceptors" added to them.
    Supposedly done by Paul Bieker. The following rough sketch shows one on top and one on the bottom of the foil. It was likely placed one side or the other.
    PeterEng, Slavi-what do you think?
    NOTE-Slavi's sketch below seems to show some benefit for a foil-could it tend to retard cavitation, Slavi?

    click(Ps I couldn't draw the foil level or nose up-the front is to the left) :

    About interceptors:

    For decades trim tabs have been the popular way to adjust a boat’s running angle. They work well on boats up to about 45 feet but on larger boats, you need some seriously big plates, which can create drag and don’t always deploy quickly. That’s why lately many manufacturers are turning to interceptors, such as those manufactured by Humphree and Naiad Dynamics. These blades mount to the transom and drop down vertically into the flow of water coming from beneath the hull to create lift without producing the drag of conventional tabs.

    [Interceptors are] an upgrade because you don’t add surface friction [like you do] with trim tabs,” says Dave Newcomb, engineering manager at Sabre Yachts in Casco, Maine. “They’re more sophisticated, and they’re precise.”

    Sabre uses Humphree’s 850-mm-wide (about 33½ inches) Interceptors on its 54 because the Volvo Penta IPS II pods that are standard power on the boat don’t have integrated tabs. They are mounted in the same position as trim tabs. The standard series lowers two inches while the extended series drops three inches. The farther the Interceptors extend, the more lifting force they generate.

    They create more lift efficiently with less drag,” explains Greg Platzer, owner of Platzer Marine in Fort Lauderdale, Florida, the exclusive U.S. Humphree distributor. Platzer says that because they can be custom designed, Interceptors can be installed in locations where trim tabs don’t always work, such as at the aft end of a propeller tunnel. They can also be retrofitted to a boat that has conventional trim tabs or had none at all. While some critics question the effectiveness of interceptors at slower speeds, Platzer says he has installed them on trawlers where they work just fine.

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    Pictures,L to R --1) sketch and info of a foil using an interceptor(hard to see in sketch) by Slavi(found under "interceptors" on google) .
    2) illustration of an interceptor used to replace trim tabs on a powerboat(see above), 3) my rough sketch of how it might be used :
     

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  15. El_Guero

    El_Guero Previous Member

    I think it would be more than just two sticks in the water to do much control.

    I would lean towards something like flaperons, or just simple flaps, or even leading edge slats .....

    Whatever they used was very stable, I could see the difference in the two boats as the NZ team bobbed a lot - loss of energy from forward velocity to up and down velocity. And when the Oracle boat was on plane, she was on PLANE.

    That makes me want to vote for leading edge slats of some kind ....
     
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