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ACC canoe body lines-latest trends & hydrostatics

Discussion in 'Yacht Designers Discussion' started by yades, May 23, 2007.

  1. yades

    yades New Member

    Joined:
    May 21, 2007
    Messages:
    7
    Location:
    ITALY
    Hi all!

    I'll like to share with the community what to my opinion could be the outcome of a modern ACC canoe body lines plan under the present rule version 5 and following the modern trends, as viewed in Valencia and generally on posted images in the net. I’d also thought to attach the basic Hydros calculations resulting and main ratios which could give in such a way further ideas for conjectures and observations.
    Perhaps it could be of somewhat interest as not much of hull lines plan is available around the net (even less in yacht design forums in general ....as far as I can see...).
    Furthermore, it seems to me important to stress the fact that the most consolidated opinion in the latest ACC projects, is that such ultimate achievements in hull canoe body design, as a result of an extensive and thorough R&D work during the past recent years, has reached the extend where …..”jump in performance, are no longer possible within the constraints of the existing ACC Rule”….(P. Van Oossanen-MDY’04).
    This is the main issue after all !!! ;)
    I personally recon as with regard to the recent past races of the 32nd AC that the prevailing wind conditions are to be considered mainly around 9 to 11 knots and to this basic assumption the following criteria could be proposed for the project of an allegedly hull lines plan.
    Following the above mentioned, the basic design criteria of an ACC canoe body hull lines plan for a first version of this project (i.e. moderate winds hull) could be as follows:

    - Design Velocity Ratio=1.60 to 1.62
    - Prevailing wind speeds 7 to 10,5 kts (force 3 Beauf.)
    - Hull Vmax =12,35 kts
    - Designed yacht speed =8,5 to 9,5 kts (70 to 78 % Vmax)
    - Designed TQ =1,10 to 1,24
    - Corresponding FN = 0,33 to 0,37
    - Corresponding optimum Cp range (canoe body only) 0,535 to 0,576
    (here I'd preferred to mantain the Cp towards 0,535...- version A as
    you outlined -)
    - BWL/LWL ratio the minimum as possible = 0,20 giving BWL=3,60 m. ca.
    - Extreme U transverse hull sections leading towards Cm values in excess of O,90.
    - On the above basis Tc (canoe body draft) seems somewhat reasonable
    around 0,710/0,720 m (i.e. from the approx. formulaTc=(Displ/(LWL*BWL*Cp*Cm))
    - From which an approx idea of (WSA) Wetted Surface Area - canoe body
    only via an other preliminary approx. formula involving BWL, Tc, Displ. Vol.,LWL and Cm- brings a reasonable value for the WSA of about 55 to 57 sq. m. A very good starting point indeed.
    - Ending with a ratio SA(Sail Area)/WSA = 5,80 ca. !!! ..."star wars"... values
    existing only for the ACC Yachts !!!.....

    These are the basic concepts for starting an ACC hull lines project for discussion and speculation on this forums(..to my very personal opinion....and if os somewhat interest.....). Comments are always appreciated.:cool:
  2. yades

    yades New Member

    Joined:
    May 21, 2007
    Messages:
    7
    Location:
    ITALY
    I wonder.!!.....

    Is any body interested to exchange ideas/impressions on the present thread?? So far I dont see any specific attention caught by this matter and I'm wondering wheather could be of any interest inserting the hull lines+hydrost calcs for an allegedly ACC canoe body elaborated under the present AC rule..... :rolleyes:

    Any comments?? :cool:
  3. Innomare

    Innomare Senior Member

    Joined:
    Dec 5, 2004
    Messages:
    233
    Location:
    The Netherlands
    Hi Yades,

    Yachtforums is more focussed on the users, crew and yacht lovers in general. You'd get a lot more response posting this on the forum at www.boatdesign.net (if you haven't already).

    Good luck!

    Bruno