Ballast/Dsplacement Ratio

Discussion in 'Stability' started by cenej, Jan 12, 2008.

  1. Antonio Alcalá
    Joined: Nov 2006
    Posts: 92
    Likes: 3, Points: 0, Legacy Rep: 45
    Location: Portugal

    Antonio Alcalá Ocean Yachtmaster

    I get it ! Guillermo. I finally did it!

    Take a look..

    PUMA 34

    NAO GLASS ESP

    year :75

    Polyester


    LOA(m):10.35


    LWL (m):8.20

    Beam (m):3.35


    Draught (m):1.85


    Sloop Rigged (m2):65.00


    weight (t):5.400 kg


    ballast (t):2.400 kg

    and

    FIRST 345

    Quillard
    Longueur hors tout: 11.00 m
    Longueur de coque: 10.55 m
    Flottaison: 9.08 m
    Maître Bau: 3.49 m
    Hauteur sous barrots: 1.92 m
    Tirant d'eau: 1.45 ou 2.02 m
    Déplacement: 5700 kg
    Lest: 2050 kg
    Grand-voile: 25.70 m²
    Génois: 41.00 m²
    Spi: 90.00 m²
    Jauge: 10.30 Tx
    Catégorie maxi: 1ere
    Matériau: Polyester
    Construit de: 1984 à 1987
    Architecte: Berret
    Chantier: Bénéteau
    Pays: France


    These data are fine, trust me. Source: http://www.voilic.com/#VOILIC


    Waiting numbers...

    Best Winds
     
  2. Guillermo
    Joined: Mar 2005
    Posts: 3,644
    Likes: 185, Points: 63, Legacy Rep: 2247
    Location: Pontevedra, Spain

    Guillermo Ingeniero Naval

    Well done Antonio!

    FIRST 345

    INPUT
    Loa = 11,00 m
    Lh = 10,55 m
    Lwl = 9,08 m
    Bmax = 3,49 m
    Bwl = 3,14 m
    Draught T = 1,45 m
    Body draught Tc = 0,57 m (WILD GUESS. Profile missing)
    Moulded depth H = 1,75 m (WILD GUESS. Profile missing)
    Disp = 5700 kg
    Ballast = 2050 kg
    Sail area = 50,73 m2
    Mast height = 15,01 m
    Heeling Arm = 6,58 m
    Power = 21 KW

    OUTPUTS
    Length/Beam Ratio (2Lwl + Lh)/3B = 2,74
    Lwl/Bwl Ratio Lwl/Bwl = 2,89
    Length/Draught Ratio Lh/T = 7,28
    Beam/Draught Ratio Bmax/T = 2,41
    WL beam/Body draught Bwl/Tc = 4,69
    Ballast/Disp Ratio W/Disp = 0,36
    Displacement/Length Ratio D/L = 212,37
    Sail Area/Disp. Ratio SA/D = 16,16
    Sail Area/Wetted surface SA/WS = 2,05
    Power/ Disp. Ratio HP/D = 2,27 HP/ton
    Hull speed HSPD = 7,31 Kn
    Potential Maximum Speed PMS = 7,90 Kn
    Velocity Ratio VR = 1,08
    Best motoring speed (1.1) CSPD = 6,00 Kn
    Capsize Safety Factor CSF = 1,97
    Motion Comfort Ratio MCR = 24,00
    Roll Period T = 2,78 Sec
    Roll Acceleration Acc = 0,12 G's
    Stability Index SI = 0,80
    Angle of Vanishing Stability AVS = 120 º
    Dellenbaugh Angle DA = 16,13 º (14 kn wind)
    Wind pressure coefficient WPC = 1,31

    Estimated STIX 38,68

    As moulded depth is relevant to calculate STIX, the figure here has to be taken with more care than usual.

    NOT TRUSTABLE NUMBERS!

    Cheers.
     

  3. Guillermo
    Joined: Mar 2005
    Posts: 3,644
    Likes: 185, Points: 63, Legacy Rep: 2247
    Location: Pontevedra, Spain

    Guillermo Ingeniero Naval

    Using your numbers for the Puma 34, except for sail area, and guessing a lot:

    INPUT
    Lh = 10,35 m
    Lwl = 8,20 m
    Bmax = 3,35 m
    Bwl = 3,02 m
    Draught T = 1,85 m
    Body draught Tc = 0,63 m (WILD GUESS)
    Moulded depth H = 1,75 m (WILD GUESS)
    Disp = 5400 kg
    Ballast = 2400 kg
    Sail area = 55 m2 (WILD GUESS)
    Mast height = 15.5 m (WILD GUESS)
    Heeling Arm = 6.94 m (WILD GUESS)
    Power = 13,5 KW


    OUTPUT
    Length/Beam Ratio (2Lwl + Lh)/3B = 2,66
    Lwl/Bwl Ratio Lwl/Bwl = 2,72
    Length/Draught Ratio Lh/T = 5,59
    Beam/Draught Ratio Bmax/T = 1,81
    WL beam/Body draught Bwl/Tc = 4,79
    Ballast/Disp Ratio W/Disp = 0,44
    Displacement/Length Ratio D/L = 273,17
    Sail Area/Disp. Ratio SA/D = 18,16
    Sail Area/Wetted surface SA/WS = 2,43
    Power/ Disp. Ratio HP/D = 1,54 HP/ton
    Hull speed HSPD = 6,95 Kn
    Potential Maximum Speed PMS = 7,82 Kn
    Velocity Ratio VR = 1,13
    Best motoring speed (1.1) CSPD = 5,71 Kn
    Capsize Safety Factor CSF = 1,93
    Motion Comfort Ratio MCR = 25,85
    Roll Period T = 2,96 Sec
    Roll Acceleration Acc = 0,10 G's
    Stability Index SI = 0,88
    Angle of Vanishing Stability AVS = 126 º
    Dellenbaugh Angle DA = 24,06 º (14 kn wind)
    Wind pressure coefficient WPC = 0,88


    Estimated STIX 37,14

    The same as before:
    NOT TRUSTABLE NUMBERS!

    Cheers.
     
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