Multi 50 Design Rule: no vertical lift!

Discussion in 'Multihulls' started by Doug Lord, Aug 4, 2012.

  1. Doug Lord
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    Doug Lord Flight Ready

    I've been curious why a modern trimaran would be designed without lifting foils for ocean racing. Here is the (unfortunate) answer:


    2.6.4 Lift ( See Open 50 Rules pdf at the bottom of this page)
    General remarks:appendages must not provide vertical lift (beyond the Archimedes principle and lift relating to the heel of the boat).
    For the requirements of these rules,a lifting plane is all or part of an appendage which could create vertical lift at zero heel,with the exception
    of the following:
    -*‐Rudder blade whose maximum angle along the longitudinal axis is less than
    10°,at zero heel and with the steering centred. Any protrusion of less
    than 10 mm on a section of the appendage, measured at its attachment point,
    and extending less than 50mm from the profile(fences).

    Any appendage shape which could provide lift (beyond the Archimedes principle) by acting as a foil is strictly forbidden,as well as any angulation of
    daggerboards. Plates which create a lifting surface on rudders and daggerboards are forbidden.

    ===============
    This is a classic example of a rule retarding development of a Class. As has been proven time and again in other classes, racing trimarans with curved lifting foils have superior speed and handling at sea. It's a damn shame, in my opinion, that antiquated rules of this type are still around!

    Multi 50 Class Association: http://www.class-multi50.org/en/english.html

    Picture: Multi 50 Prince de Bretagne getting a little(!) vertical lift from her ama foil :
     

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  2. warwick
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    warwick Senior Member

    Or is it just a vertical dagger board, and Doug reading to much into it.
     
  3. Silver Raven
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    Silver Raven Senior Member

    'warwick' - so what is your answer ??? What is your practicle - workable resolve to this problem ???

    If Doug &/or others are or might be "reading to much into it" then - what is your suggestion to solving this dilemma ???

    Have you an answer as to how we can resolve this matter - at the 'coal-face' ??? I'd sure like to know - what we can do to fix it. Ciao, james
     
  4. warwick
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    warwick Senior Member

    What I was referring to was the photo, as the dagger board looked to be to vertical to be providing lift
     
  5. Doug Lord
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    Doug Lord Flight Ready

    Multi 50

    ============
    Warwick, the picture has no serious relevance to the Multi 50 rule-I just thought it was a neat looking illustration of a tri flying the main hull. However, it dawned on me that at that angle-probably around 15-18 degrees -that the lee foil would be capable of producing a slight amount of vertical lift. But, alas it would do little good because of the effect the heel has on the rig. Nice picture, though. And too bad they don't allow curved lifting foils......
     
  6. warwick
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    warwick Senior Member

    My apologies to you Doug, as you seam to focus on lifting foils a lot of the time, may be that is your interest in development.

    May be part of the problem lies these days of focusing on the human element to try and make things as even as possible, to the detriment of development.
    It seams be happening in all forms of competition.

    Was the idea to simplify the class/ boats compared to the ORMA 60s.

    Any Ideas as to why the 40 foot class died out so quickly yet the monohull version has taken off.
     
  7. Doug Lord
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    Doug Lord Flight Ready

    ========================
    No apology necessary....
     
  8. Corley
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    Corley epoxy coated

    The answer is that commercial realities of the Multi50 which is an entry level class dictate that a tight developmental framework be put in place to minimise costs. There has been substantial development in Multi50's over the years (even if it's not in the direction a certain individual on the boat design forums would like) and the class has survived where ORMA required a total rethink thanks to spiralling costs and a steady reduction in the sponsors willing to fund the teams. They have come up with a pretty good concept and the boats are quite quick I'd certainly back them in ocean racing over any other multi short of one of the final ORMA's or MOD70's. It's also an accessible boat to teams on a low budget and entry and operating costs of a used boat are far less than an ORMA. The class has flourished in a niche and sponsors with lower budgets can fund a team.

    The big question is really where are the billionaires and large companies outside of France who are willing to fund ocean racing multihulls? Formula 40 had the US Randy Smyth team and a few British teams early on but they are all gone now. It seems that while many people around the world admire and are interested in multihull racing it's hard to put together a sponsorship deal to make it work. The operating costs of a large multihull would not be greater than running a J boat campaign or even a standard maxi campaign but it has failed to gain traction outside of France, hopefully the MOD70's on tour will get some more potential sponsors excited.

    With the ORMA's they found was that when the boat was developed within a box rule and all the boats were at the extremes of the box it made more sense to go one design as the boats were reaching a point where they had explored most of the options and were becoming inherently similar. Since all the boats are the same you can have a supply of parts shared among the teams and amortise the cost of construction over a number of craft then the negatives of custom construction are reduced. This also makes for a more attractive package to take to the sponsors and you can give them some certainty of your team operating expenses. This is illustrated by the breakages on the recent Krys Ocean Race. Steve Ravussin's Race for Water will be able to pull a daggerboard out of the parts store and Sidney Gavignet's Mussandam team will be able to pull a lifting foil. The parts are jointly funded by all the teams to reduce costs and dont need to be custom made to fit a particular boat.

    For a look into the sponsorship and business aspects of yacht racing I like reading up over here.

    http://www.yachtracing.biz/
     
  9. yves
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    yves Junior Member


    Yes exactly, the Multi50 were never meant to be a too high tech class as the Orma 60s to my knowledge (and the spot for the "no limit high tech" having been taken by the Imoca following the Ormas demise more or less, at least in France)).

    Personnally what I would like to see is a pure displacement based class : like the "open 8 tons class" or open 10 tons.

    From a naval architecture perspective would be the most interesting thing seems to me.

    (but very tough to set up for weighting the boats and for precise wieght estimation for construction most probably)
     
    Last edited: Aug 7, 2012
  10. Samnz
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    Samnz Senior Member

    is your answer Douglord.

    and its more popular now than the orma 60 class coz its cheaper, foils are expensive, to add more expense% than performance% in a lot of cases

    Do you have any idea how much foils/bearing cost? more than my floats!
     
  11. Doug Lord
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    Doug Lord Flight Ready

    Multi 50 Rule

    ================
    Yes, I do. For the F-32 SR, RETAIL pricing is:

    1- set of two foils=$6499US
    2- set of two trunks= $1990US

    Of course if you're good with tooling and or one off carbon development you could save a lot.
    I can see how some think this is a good thing to reduce costs at a dramatic cost in maximum performance and seaworthiness(yes, foils make a high speed tri more seaworthy), but I think it is a big mistake......
     
  12. Corley
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    Corley epoxy coated

    Yep those damn French, they know nothing at all about foils or their application to multihulls and associated costs. Thank goodness we have Doug and his foil crusade to show them the error of their ways.
     
  13. Samnz
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    Samnz Senior Member

    with all due respect DL this whole thread is basically proving foils aren't really the future/arent required in modern very fast Multihulls so im not sure why you started it?
     
  14. Doug Lord
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    Doug Lord Flight Ready

    =====================
    That seems to fly in the face of the facts since almost all record breaking multihulls are using lifting foils-BP5, IDEC, Sodebo,MOD 70's,AC 45's ,AC 72's, C Class cats, A class cats, NACRA 20, the Olympic NACRA 17 and many more. Except in classes where they are outlawed lifting foils WILL be used because they are faster and improve handling ,period.
    And the point of the thread for those who might glance at a Multi 50 and say: "See they don't use foils. If foils were so great they'd be using them too" is that the Multi 50 can't use foils because the rule forbids it and that is just plain unfortunate.
     

  15. Doug Lord
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    Doug Lord Flight Ready

    ==================
    What a comment, Corley!
     
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