Vendee Globe 2012

Discussion in 'Sailboats' started by Doug Lord, Apr 6, 2012.

  1. Gary Baigent
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    Gary Baigent Senior Member

    "The one problem with this approach is the boat is more likely to stay turtled if turtled, as the fixed ballast is not likely to be sufficient to right it."

    Sharpii, this was also said of the big daggerboard lightweights of the late '70's - but they all bounced back upright from knockdowns, surviving in very savage NZ conditions. Remember these board boats carried only enough ballast in their boards to make them neutral to slightly negative (to sink them); but they carried internal hull ballast, not a large weight like the US board examples from Hood and Chance of the same period - because the Kiwi designs were very light displacement - also compared to sail plan designs of today, the Antipodeans were very moderate and actually low rigged, yet they still won many races.
     
  2. tomas
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    tomas Senior Member

    My apologies for the pedantic tone.

    If our comments here are any indication, the next Vendee Globe racers will exhibit some fundamental changes in contrast to what we've seen during this iteration.

    I personally am not criticizing the engineers of these vessels, more the priorities that have guided the questionable design choices and decisions that were made.
     
  3. Doug Lord
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    Doug Lord Flight Ready

    ==============
    The "standard" configuration for DSS is a small fixed keel plus the foil. The foil produces RM comparable to or in excess of the max produced by a canting keel.
     
  4. motorbike
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    motorbike Senior Member

    Any engineers or designers like to comment on this assertion? It seems to me that DSS is a high tech "flopper stopper" at low speeds and would only provide significant RM at speeds fast enough to produce lift and overcome drag. DSS sounds almost too good to be true from DL's description.
     
  5. sharpii2
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    sharpii2 Senior Member

    It is relatively easy to design a boat that will right from a 90 deg. knock down. You don't even have to have ballast. Just flair the sides and you're good to go.

    In a skillfully handled crewed boat, there is always someone on watch, keeping the boat from getting into the trough of a breaking wave. Single handed is another matter. Usually the 'crew' is doing everything but piloting the boat. He has robots to do that (wind vanes and auto pilots).

    For this reason, the singled handed boat is far more likely to be rolled over in bad conditions than the fully crewed one, with a skilled crew.

    The canting keel, for it's major drawback, the high likely hood of structural failure, is quite effective at making the boat unstable while upside down (providing, of course, it stays intact).

    I just don't see this happening with a shallow hull form (considerably wider than it is deep), and internal ballast.
     
  6. Doug Lord
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    Doug Lord Flight Ready

    ==========
    I'm a designer and I stand by that quote 100%. You don't have to be a rocket scientist to realize that is correct-you either need to read more or just figure it out yourself. Of course DSS works when the boat is moving-thats why it is called "Dynamic Stability System".
    DSS is always used with a fixed keel with enough ballast to right it from a knockdown.
    It is legal in the Open 60's and if they don't go one design you'll probably see it used on an Open 60 before too long. There is already a Mini Proto that hasn't been launched yet using DSS.
    The fact that DSS generates so much RM is why boats using it can be narrower than they would be otherwise and carry more SA. And that is why DSS benefits the boat in light air as well when it is retracted and the boat still has the large SA and narrow waterline.
     
  7. Doug Lord
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    Doug Lord Flight Ready

    ===================
    Sharpii, as mentioned in my previous post DSS boats can be much narrower than boats using other current forms of RM. As I said, that is an advantage in strong or light winds.
    What doesn't necesssarily work too well is converting an existing boat to DSS-it needs to be designed from scratch for the system.
     
  8. Doug Lord
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    Doug Lord Flight Ready

    Vendee

    =================
    Anybody heard more about de Lamotte's situation?

    =========================
    UPDATE- just found this and the picture on the Vendee site:
    ("drift" = board)

    Hi all,

    I managed to move the drift at end of the day yesterday... I decided not to return in the water, it was too tiring and it became dangerous as my state of tiredness increased. But in a final desperate attempt, I removed the tip and the drift moved it slowly. I managed to it back into its "normal" position.

    It is very damaged but I left about 80cm of healthy drift under the boat in order to use it. I then plugged the waterways with my dirty laundry to limit the speed of the "tide".

    There are 18 knots of wind and I sail between 6 and 8 knots. The electric pump allows to me to rest. Tomorrow, I will attack the resin workshop and I hope I’ll be able to eliminate the waterways. In the meantime, I am glad to have completed this first task.

    And mentally, I'm on the road back to Les Sables... I finally get some rest.

    Have a Good day,

    Tanguy
     

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  9. capt vimes
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    capt vimes Senior Member

    in my opinion, foils can give you an edge... nothing else
    http://www.boatdesign.net/forums/sailboats/speed-dream-27-prototype-39798-20.html#post610944

    they work on a flat sea - granted.
    but if you take the effect from the foil into the RM calculations and ultimately into the stability calculations, it will get dangerous on the wide ocean...

    i personally do not want to be on a boat where nzig% of the RM comes from a thin wing somewhere in the water... if it is in the water...
    and if it is not in the water, you loose nzig% of RM in an instance and just can hope that the boat does not capsize...

    keep foilers foilers and keep ballasted boats, well ... ballasted boats... ;)
     
  10. Doug Lord
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    Doug Lord Flight Ready

    ================
    As I said earlier: DSS is always used with a ballast keel!!!
     
  11. capt vimes
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    capt vimes Senior Member

    i do not understand the discussion here about canting keels being the one and only point of failure...

    i do not think that the loss of 3 keels in this race had anything to do with the canting mechanism.
    its the keelblades which were obviously not up to the task... if you now fix the keel to the hull and take away all the canting mechanics, you still have a weak because thin and light keelblade...
    do you think that this fixed blade is then not prone to snap?

    in my opinion going back to fixed keel designs would not help at all.
    the keelblade and mounting should be looked at and probably get more regulated...
     
  12. Doug Lord
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    Doug Lord Flight Ready

    ------------------------
    Good points. Using DSS the keel might be lighter....
     
  13. CT249
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    CT249 Senior Member

    Good thoughts, but we CAN "go back", in that we can institute rules that reduce performance. It's been happening since the reaction to the L x SA rule boats of the late 1800s; people like Herreshoff and the IYRU stopped their excesses by introducing new rating rules. The shorthanders introduced rules to limit LOA and reduced the maximum length from 236' to 60'; F1 cars banned turbos, large wings, ground effect, fan cars, active suspension etc etc et; sportscars reduced engine power etc; swimming banned the streamlined suits, highjumping banned the Frosby flop, javelins and golf balls and clubs were restricted to reduce performance, etc etc etc.

    So we certainly CAN go back and unwind the performance. After all, the whole focus of shorthanded 60 footers seems to have moved from the tris to the monos over the past decade or so, and that has dramatically reduced performance.* If people are happy to reduce speed by 1/3 by switching from multi to mono then how could they quibble about reducing speed by 1/10 by going from canter to a boat with a more solid keel?

    * Yep, part of the mono's appeal has been the RTW racing but they also seem to be dominating transatlantic racing, and of course one could say that if speed was all then there would be a singlehanded multi RTW race.
     
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  14. capt vimes
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    capt vimes Senior Member

    if you mean the fosbury flop - it hasn't been banned, it is the only technique used nowadays... ;)
    but longjumping banned the salto... you are not allowed to do a rotation in air, which would increase the distance jumped dramatically...

    all other points mentioned are vallied but i am no friend of neither and as i stated above, the canting keel is not the problem...
    it is the blades, the keelfin failing and not the fact that they can be canted...
     

  15. tomas
    Joined: Nov 2012
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    tomas Senior Member

    What is happening with di Benedetto from Team Plastique?

    His speed is consistently in the single digits while others are consistently faster.
    Is something on his boat broken or?
     
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