AC 36 Foiling Monohulls

Discussion in 'Sailboats' started by OzFred, Sep 13, 2017.

  1. OzFred
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    OzFred Senior Member

    I don't think energy recovery is needed, and it would slow down the movement of the keel. A battery to last a 30 minute race (maybe 20 swings of the keel, assuming a "no pre–start canting" rule) doesn't need to be that big. Also, a small flap on the back of the keel just above the bulb would likely assist in moving the keel quickly and reduce the energy required.

    The flap could also provide additional RM quite efficiently. I thought canting keels already have an offset on the axis of rotation to provide a small negative AoA for the entire keel. The flap might introduce some significant torsion though.
     
  2. Doug Lord
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    Doug Lord Flight Ready

  3. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    New boat 75'. No more design details until Nov. 30........
    SEE NEW PROTOCOL SUMMARY PDF BELOW.....


    Boat in the revised sketch 78'. Boat in original sketch 75.5'


    NZAC revised   9-7-17 003.JPG

    NZAC ONE     9-25-17  dl 002.JPG
     

    Attached Files:

    Last edited: Sep 28, 2017
  4. michaeljc
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    michaeljc Senior Member

    75 ft monohull. Anyone prepared to place bets on it being foiling? I am saying no

    The defender cannot take part in the challenger series: Good!

    20% crew of country nationality, remainder must reside in challenger country for over one year prior: Good!

    Hull must be constructed in country of challenge: Good!

    Its back to traditional fundamentals. Good - if teams don't like, it don't come. Tradition is still of value. Its the oldest sporting trophy in the World. May the best men win - which brings me to another point: why are there not any women in the crews? Time to bring some in , I recon
     
  5. Dolfiman
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    Dolfiman Senior Member

    Foiling assistance : I bet yes, foils, fixed keel and no water ballast (e.g. Figaro 3 config.) can suit the one to one match racing and can add speed. This is in tune with the current development on offshore racers from 60' to maxi yacht 100' +

    Nothing on the RM : should be ruled ? For Imoca, it is 25.5 t.m at 25° heel angle

    Strong winds : up to ? Important for the % of foiling assistance to design

    Timing is short for design & launch + no towing tank & wind tunnel tests authorised : monohull at the edge of the current state of art, optimisation thanks to pre existing numerical softwares and VPP, no possible exploration of innovation outside of this frame
     
  6. schakel
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    schakel environmental project Msc

    And here is the new protocol for AC36:


    In short:

    1. RNZYS Commodore Steve Nair should never, ever try to pronounce an italian name again.
    2. The boat is a 75-foot long monohull, and the design details will be complete by next spring
    3. Cost containment is a fundamental principal
    4. The boats will need to be build in the country challenging.
    5. Nationality rule: Citizenship requirement is a mere 20%, the rest of the sailing team needs a strict residency requirement in the country they are representing. “It’s not a strict thing, but it’s an attempt
    6. Cup is Auckland 2021, but there’s no infrastructure or plans yet. 2019 and 2020 there will be pre-regattas.
    7. Two boats allowed per team.
    8. Challenger series will be organized by the CoR. AC will be organized by the defender. Joint group for broadcasting/sponsorship/umpiring and other common issues.
    9. Facebook Live means journalists can stay at work or at home, cause they sure didn’t show up to the press conference. Thank you ETNZ!
    10. “They might be” foiling. The next boat will be presented in November and it ‘definitely will be an exciting boat’.
    11. Some one-design componentry, some supplied parts likely. Development ‘open in the really important areas’.
    12. 10-12 crew, bicycles allowed.
    13. No tank testing allowed, no wind tunnels.
    14. If for any reason, it can’t be in Auckland, it’ll be in Italy.
    15. Prada Cup. Yes, Louis Vuitton is gone, and Prada is not only title sponsor of the challenger series, but presenting sponsor for the big one. Does LV have the balls to return on a Challenger’s sails?
    16. Independent regatta directors and race management, similar to Bermuda setup for RM.
    17. Longer races, ~40 minutes. Longer pre-start, upwind start.
    protocol announcement.PNG
    Emirates Team New Zealand https://www.facebook.com/EmiratesTeamNewZealand/videos/1886996041325439/

    Source: www.sailinganarchy.com
    .
     

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  7. schakel
    Joined: Jul 2008
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    schakel environmental project Msc

    What I found appaling is that no windtunnel and towing tank test are allowed.
    Formula 1 uses this, motor races uses this, Top cyclist use windtunnels.
    It's expensive, yes, but gives very good results.

    If a cyclist from the tour the France can afford it, why not a AC team?
    Cost aren't that big. Pennywise, poundfoolish.
    Especially the towing tank and the windtunnel gives the biggest advantage price-wise.
    But that's my humble opinion.
     
  8. OzFred
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    OzFred Senior Member

    Yes, it's a bit counter–intuitive to say they want to contain costs, then specify a 75' boat. I guess that puts them at the upper end of the 12 metre class in terms of length.

    I wouldn't rule out foiling, but it does make at least upwind foiling less likely, perhaps that's intentional. There is only about 12 months from release of the detail (31 March 2018) to design, build and start training in the first boat for the pre–regattas.
     
  9. Dolfiman
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    Dolfiman Senior Member

    After all, 75' is a bit logic :
    at 50' no chance to show higher speeds than a standard Imoca or Vor,
    at 60' confusion with two well established offshore classes themselves in a convergence process, and their speed capacities uneasy to equalize with fixed keel and no water ballast
    >>> at 75' you are at about twice the displacement of a 60', so significantly more powerful with a weight of 14-15 t still reasonable. Can give races at average speed boat 20 knots most of the times with peak speed occurence at 30 knots, good for the (TV) show.
    Again, said "strong winds" should be specified, 25 knots in sheltered seas ? or 30 knots and its full established sea state ?
    28-35 knots, 2,5 to 3m swell >>>
     
  10. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

  11. Doug Lord
    Joined: May 2009
    Posts: 16,088
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    Location: Melbourne, Florida

    Doug Lord Flight Ready

    NZAC Sailplan ,version one
    Based on these calcu-guestimates:
    A) At 90 degrees the force holding the boat there is 171,926 ft.lbs.
    The force trying to right the boat is 483,800lb
    1-keel weight 19782 lb @ 20'
    2-buoyancy from pod-4608lb @20'
    -- "A" means that the boat is self-righting from a knockdown.....
    -
    3- Wing mast 115' above deck
    4- SA=3191 sq.ft. incl wing mast
    -----
    B) Weights----
    1) hull weight-8572 lb
    2) keel weight 19782lb
    3) rig weight 2915lb
    4) crew weight 1900lb
    5)TOTAL DISPL.= 33168 lb
    -----
    C) RM on Foils:
    1) HM at 59' with 2.5lb/sq/ft. pressure= 470,672 ft.lb.
    2) RM, boat slightly heeled, mast vertical=569,418 ft.lb.
    -----
    D) Foil Loading one main foil in the water supporting 80% of the load=
    18' X 2.5' chord foil fully immersed=589lb/sq.ft.
    -----
    E) Boat may need canting keel NOT for ultimate RM but to get started. Needs much more study but all in all probably has great potential IF the target weight can be met.


    NZAC SAILPLAN, version 1,  9-29-17 004.JPG

    NZAC ONE     9-25-17  dl 002.JPG

    NZAC revised   9-7-17 003.JPG
     
    Last edited: Sep 29, 2017
  12. michaeljc
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    michaeljc Senior Member

  13. michaeljc
    Joined: May 2013
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    Location: New Zealand

    michaeljc Senior Member

    I cant see foils out on outriggers or stability pods. What I can see is a very wide beam. One thing is for sure - they will look beautiful when hard into the wind. Dalton mentioned that they need 5 m of water depth. There will be keels with ballast IMO
     
  14. OzFred
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    OzFred Senior Member

    14 to 15 ton is "reasonable"? That's 3 to 4 times the weight of the AC50 cats (thought I don't know their all–up weight, I can only find "hull weight" of around 2.4 tonnes). I'd have thought they'd need to slim down a lot lower than that. They likely won't have motors or fuel, or water ballast, so that helps, but they will have hydraulics with 8 to 10 crew peddling…
     
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  15. Doug Lord
    Joined: May 2009
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    Location: Melbourne, Florida

    Doug Lord Flight Ready

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