Stability and STIX in German Frers Designs

Discussion in 'Stability' started by Antonio Alcalá, Nov 13, 2007.

  1. Antonio Alcalá
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    Antonio Alcalá Ocean Yachtmaster

    Why do you think is so different the STIX in old designs of Frers and new designs?

    For example: A well known long distance racer cruiser SWAN 44 MKII, has a STIX of 38. She scores exactly the same that the Vancouver 28 and only 1 point mora than the Oceanis 461 (37). Anyway the 48 ' new Hallberg-Rassy has STIX 58 at minimun load.

    All Grand Soleil in 1988-93 were designed by German Frers, now I bring your attention about this model:

    Gran Soleil 52:

    LOA: 16.60 m. - Beam: 4.75 m. - Draft: 3.20 m. Seldem Mast: 22m


    LWL: 12.89 m Displacement: 17 700 Kg Ballast : 7 300 Kg

    Sail Area :157.40 m²

    What do you think about stability parameters? I don´t know her STIX

    Which sailboat would you prefer to cross the Pacific, this one (GS 52) or the new Hallberg-Rassy 37 ( STIX 49)?


    Best Winds
     

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  2. Guillermo
    Joined: Mar 2005
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    Guillermo Ingeniero Naval

    Some estimated numbers for the Grand Soleil 52 (As per data at Grand Soleil pages)

    Loa = 16,30 m
    Lh = 15,78 m
    Lwl = 12,89 m
    Bmax = 4,75 m
    Bwl = 4,28 m
    Draught T = 2,40 m
    Body draught Tc = 1,00 m (guess)
    Disp = 17700 kg (Most probably lightship or MOC)
    Ballast = 7300 kg
    Sail area = 157,4 m2 (guess: 140 m2 for 100%)
    Power = 95 HP


    Length/Beam Ratio L/B = 2,9
    Lwl/Bwl Ratio Lwl/Bwl = 3,02
    Ballast/Disp Ratio W/Disp = 0,41
    Displacement/Length Ratio D/L = 230 (around 265 in MLC)
    Sail Area/Disp. Ratio SA/D = 20,95
    Power/ Disp. Ratio HP/D = 2,44 HP/ton
    Hull speed HSPD = 8,71 Kn
    Potential Maximum Speed PMS = 9,95 Kn
    Velocity Ratio VR = 1,14
    Best motoring speed (1.1) CSPD = 7,15 Kn
    Capsize Safety Factor CSF = 1,84
    Motion Comfort Ratio MCR = 34,20
    Heft Ratio HF = 0,97
    Roll Period T = 3,94 Sec
    Roll Acceleration Acc = 0,09 G's
    Stability Index SI = 0,83
    Angle of Vanishing Stability AVS = 121 º

    Mmmmmm.....

    I don't have enough info to calculate her STIX, but by the upwards numbers I doubt it will come up to 52. Probably less.
    But I may be wrong. You should try to get info from Cantieri del Prado or German Frers himself.

    On the HR 37 vs GS 52 thing, you know: 'caballo grande....'
     
  3. Guillermo
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    Guillermo Ingeniero Naval

    Diana 60 seems to be a nicer boat for the job, to my taste. Do you know what her Lwl is?
     
  4. Antonio Alcalá
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    Antonio Alcalá Ocean Yachtmaster

    Guillermo, the keel in GS 52 is not 2.70, is 3.20 .Could we change something in stability numbers including the stix?
     
  5. Antonio Alcalá
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    Antonio Alcalá Ocean Yachtmaster

    Diana 60:

    LOA:18.11 LWL: 16.50 Beam: 4.80 Draught:2.20 Displacement : 30.000Kg

    Ballast: 12.500

    Let me know your great numbers, friend

    A.
     
  6. Antonio Alcalá
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    Antonio Alcalá Ocean Yachtmaster

    Guillermo: Could we compare the 1992 52' Grand Soleil to the new Oceanis 523?

    This are her numbers:

    OCEANIS Clipper 523
    PRINCIPAL SPECIFICATIONS
     Design: Groupe Finot.
     Length overall: 16.20 m.
     Waterline length: 15.80 m.
     Hull beam: 4.88 m.
     Dry weight: 15800 Kg.
     Air draught: 22.30 m.
     Deep draught: 2.30 m (4400 Kg).
     Shallow draught: 1.80 m (option 4960 Kg).
     CE Certification:A12 / B13 / C14.
    SAIL AREA
     Sail area: 149.00 m².
     Mainsail: 67 .00 m².
     Genoa: 82.00 m².
     Asymmetric spinnaker: 191.00 m².
    SAIL PLAN
     I : 19.88 m.
      J : 6.33 m.
      P : 18.55 m.
      E : 6.19 m.
      LP (135% Overlap) : 7.59 m.
    CE A CERTIFICATION


    If we compare with the Oceanis 473, the 523 scores 46 and the 473 51... Why exist this difference in STIX?
     
  7. Antonio Alcalá
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    Antonio Alcalá Ocean Yachtmaster

    And here you have something more if you need it, Guillermo
     

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  8. Guillermo
    Joined: Mar 2005
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    Guillermo Ingeniero Naval

    Here some numbers for the DIANA 60:

    INPUT
    Lh = 18,11 m
    Lwl = 16,50 m
    Bmax = 4,80 m
    Bwl = 4,32 m (0,9*Bmax)
    Draught T = 2,20 m
    Body draught Tc = 1,00 m (guess)
    Disp = 30000 kg
    Ballast = 12500 kg
    Sail area = 140 m2
    Power = 100 KW

    OUTPUT
    Length/Beam Ratio L/B = 3,54
    Lwl/Bwl Ratio Lwl/Bwl = 3,82
    Ballast/Disp Ratio W/Disp = 0,42
    Displacement/Length Ratio D/L = 186,27
    Sail Area/Disp. Ratio SA/D = 14,73
    Power/ Disp. Ratio HP/D = 2,05 HP/ton
    Hull speed HSPD = 9,86 Kn
    Potential Maximum Speed PMS = 9,86 Kn
    Velocity Ratio VR = 1
    Best motoring speed (1.1) CSPD = 8,09 Kn
    Capsize Safety Factor CSF = 1,56
    Motion Comfort Ratio MCR = 46,30
    Heft Ratio HF = 1,4
    Roll Period T = 5,44 Sec
    Roll Acceleration Acc = 0,05 G's
    Stability Index SI = 1,13
    Angle of Vanishing Stability AVS = 121 º

    (I would like to know how her underbody is)

    From my point of view this numbers indicate a boat better suited to ocean passages than the GS 52. Although we could say she shall not be a great performer in light airs (as per her SA/D ratio only as we do not know her WS), we should not forget this is a big boat and having smaller sails makes them more handable. Although the GP 52 may probably perform pretty well in very light airs, it will also need reefing earlier in an increasing wind.

    Also the D 60's 'hull speed' more than 1 knot bigger than that of the GS52, will allow for faster passages. And she should behave much better in rough conditions.

    The Clipper 523 has a lower STIX than your O 473, probably because is relatively lighter and has a lower ballast/disp ratio in a sallower keel.

    Cheers.
     
  9. Antonio Alcalá
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    Antonio Alcalá Ocean Yachtmaster

    And what about the Formosa 51 Ketch?
    Do you have, Guillermo, any information about the STIx ,MCR etc..?


    I know she´s a real circumnavigator but not having a fine sail performance , Am I right?
     
  10. Antonio Alcalá
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    Antonio Alcalá Ocean Yachtmaster

    I found some numbers:


    Basic quantities

    LOA:51 LWL:42 Beam :14.75 Displacement:56000 lbs Sail Area :1254

    Displacement to LWL :337 Hull Speed :8.68 Sail Area to Displacement :13.71
    LWL to Beam:2.85 Motion Comfort:53.28 Capsize Ratio :1.54
    Sailing Category: A Pounds/Inch : 2214
     
  11. Guillermo
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    Guillermo Ingeniero Naval

    Too tired today. I'll think about it tomorrow.
    Good night! :)
     

  12. Guillermo
    Joined: Mar 2005
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    Guillermo Ingeniero Naval

    Somewhat undercanvased to my taste, the Formosa 51 is difficult to tack because of its full length keel, but just because of that she displays an enviable course keeping ability. Ketch rig provide more manegeable sails, with a lower CE and a variety of sails configurations to adapt to prevailing weather, although it is a more fussy rig than the sloop. Formosas are said to be comfortable boats at sea and some owners even say they 'sail admirably' and are well adapted to the Trades across the Pacific.

    Some units of the Formosa 51 have been said to be poorly built, although there are many satisfied owners.

    All in all, just by their numbers (so not judging their condition), the Diana 60 would probably be my first choice (But I would like to have a look to the underwater profile first).

    Cheers.
     
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