2020 12 23
Examples with « Gene-Hull Sailboat_Stab1.0 » Jean-François Masset – December 2020 [email protected]
« Gene-Hull Sailboat_Stab 1.0 » spreadsheet application is here illustrated through 4 examples :
– V1 classic modern sailboat (the reference boat in « Gene-Hull Sailboat 3.1 »)
– S30, inspired by S30 / Knud Reimers
– Blue Water 39, inspired by Corbin 39 / Robert Dufour - Marius Corbin
– F3, inspired by Beneteau Figaro III / VPLP Boat V1 modern classic daysailer
Hull and appendages
Loa 10,30 m ; Lwl 8,00 m ; B 2,60 m ; Draft 1,75 m ; Light weight : 2652 kg ; Keel-bulb 1092 kg
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SA (m2) ZCE (m) Zdeck (m) Zmast (m) Main (m2) Spi (m2) ZCE spi (m) 43,61 5,37 0,85 13,23 24,09 68,34 6,35
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-300 Boat V1 / Introduction of a load and its position Xg, Zg, Yg : – for the computation of the GZ curve up to 180°, it is recommended to put Yg = 0 (Crew at center), as done here below. – at contrary, for the knowledge of the righting moment RM in sailing conditions (usually up to heel 30°), it is recommended to put an Yg representative of the crew sit windward
Mass spreadsheet with input of a load Mass Xg Zg Yg (kg) (m) (m) (m) Boat light weight (kg) 2652,06 3,711 0,020 0 Data to enter Load (kg) 300,00 2,40 0,85 0,00 Crew at center yellow cells 0,85 0,00 Crew sit windward Total >>> Mass (kg) 2952,06 3,578 0,104 0,000 Crew at center Disp. (m3) 2,88005 0,104 0,000 Crew sit windward
Computation of the GZ with a flush deck : for a first approach of the GZ curve, one can assume that the volume of the cabin roof and the recess of the cockpit roughly compensate, and that the computation with a flush deck is significant enough for an early stage project. >>> To input Kroof (%B) = 0 (Cell B53) That said, the influence of a cabin roof volume can be showed by doing also the computation with the Kroof of the project , here with Kroof = 29
Typical process : to build the GZ curve up to 180° with a step of 5°
Input an heel angle (here 20) :
Data to enter : yellow cell Results (with Yg for crew sit windward) Heel (°) 20 Disp. (m3) 2,88005 / Disp. (m3) 2,88005 > Height (cm) 3,7 Xc heel (m) 3,578 / Xg (m) 3,578 > Trim (°) 0,02 Yc heel (m) -0,343 Yg heel (m) -0,036 Zc heel (m) -0,192 > GZ (m) 0,307 Sw heel (m2) 17,79 RM (kN.m) 8,897 Bwl heel (m) 2,01 FB mini (cm) 26,9 Xf (Heel) – Xf (0°) (%Lwl) -0,69 Obliquity (°) 2,97 Check % convergence 0,00 : Disp 0,00 : X Kvol. : 1,000
The computation of the equilibrium is quasi real time (about 0,5 seconde on my PC) :
The convergence accuracy is given, here 0,00 % of the deviations for both the Displacements and the Xs.
Kvol. is the volume ratio of the keel in the water, here Kvol 1 = fully immerged.
The computation of the equilibrium is quasi real time (about 0,5 seconde on my PC). On the right side, the values of heel , trim and GZ is recopied :
Data to copy/special paste (number, format) in the table here below Heel (°) Trim (°) GZ (m) 20,00 0,02 0,307 >>> to copy/special paste (number, format) these 3 values in the table here under :
GZ data storage (by copy/special paste)
Heel (°) Trim (°) GZ (m) 0,00 0,45 -0,001 5,00 0,42 0,088 10,00 0,34 0,171 15,00 0,20 0,245 20,00 0,02 0,307
Once the complete process is done, that leads to this table here below, that you can complement by the input of another Zg if you have an uncertainty on this value at early stage : GZ data storage (by copy/special paste) Input new Zg 0,150 Heel (°) Trim (°) GZ (m) GZ (m) 0,00 0,446 -0,001 -0,001 5,00 0,418 0,088 0,084 10,00 0,336 0,171 0,163 15,00 0,202 0,245 0,233 20,00 0,023 0,307 0,292 25,00 -0,192 0,359 0,340 30,00 -0,437 0,403 0,380 35,00 -0,702 0,439 0,413 40,00 -0,970 0,465 0,436 45,00 -1,235 0,480 0,447 50,00 -1,481 0,483 0,448 55,00 -1,689 0,475 0,438 60,00 -1,857 0,460 0,421 65,00 -1,987 0,444 0,402 70,00 -2,087 0,439 0,396 75,00 -2,169 0,429 0,384 80,00 -2,235 0,387 0,341 85,00 -2,259 0,336 0,291 90,00 -2,260 0,283 0,237 95,00 -2,241 0,226 0,180 100,00 -2,196 0,167 0,122 105,00 -2,122 0,107 0,063 110,00 -2,025 0,047 0,004 115,00 -1,905 -0,013 -0,055 120,00 -1,760 -0,072 -0,112 125,00 -1,601 -0,130 -0,167 130,00 -1,416 -0,184 -0,219 135,00 -1,224 -0,234 -0,267 140,00 -1,017 -0,279 -0,309 145,00 -0,804 -0,317 -0,344 150,00 -0,589 -0,347 -0,370 155,00 -0,378 -0,365 -0,384 160,00 -0,182 -0,367 -0,382 165,00 -0,008 -0,347 -0,358 170,00 0,121 -0,290 -0,298 175,00 0,182 -0,174 -0,178 180,00 0,182 0,000 0,000 AVS (°) AVS (°) 113,88 110,32 Areas ratio Areas ratio 2,33 1,89 The angle of vanishing stability (AVS) is output : here respectively 113,88° and 110,32°
The Areas ratio (positive area / negative area under the Gz curve) are also given, representative of the stability (to avoid) in upside down configuration : the higher the ratio, the better the unstability in upside down configuration. It is a criteria relevant when sailing in open ocean conditions far from a shelter, e.g. mentioned in the Imoca class rules (Areas ratio > 5).
The corresponding GZ curves and the Trim curve are also output :
GZ curve
Blue : with initial Zg ; Red : with new input Zg
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Z 0,0 G -0,1 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 -0,2 -0,3 -0,4 -0,5
Heel (°)
Trim (computed in the fixed vertical plan)
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Heel (°) Boat V1 / Some typical heeling configurations :
At heel 15° >>> GZ = 0,245 m
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At heel 30° >>> GZ = 0,403 m
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-200 -200 At heel 45° >>> GZ = 0,480 m
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At heel 60° >>> GZ = 0,460 m
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-100 -100 At heel 75° >>> GZ = 0,429 m
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At heel 90° >>> GZ = 0,283 m
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-100 -100 At heel = 105° >>> GZ = 0,107 m
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At heel 113,88° >>> GZ = 0,000 m Angle of Vanishing Stability
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-100 -100 At heel 135° >>> GZ = - 0,234 m
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At heel 150° >>> GZ = - 0,347 m
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-100 -100 At heel = 165° >>> GZ = - 0,347 m
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At heel 180° >>> GZ = 0,000 m
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The sheet « STIX » proposes the computation of the Stability Index STIX according to ISO 12217-2 2013. 3 complementary input data are necessary, the others data being provided automatically by the Stab application : As (sails area), hCE (height of center of effort) : these data can be taken in the sheet Sailplan of « Gene-Hull Sailboat 3,1 » (here As 43,6 m2 and hCE = 5,37 m) PhiD(°) the angle of first downflooding : the norm ISO consider various downflooding angles in the formulations leading to the STIX. Here to simplify and to be conservative for an early stage approach, we consider only one angle PhiD assumed to correspond to e.g. the first downflooding of the companionway top corner (here let's take 95°).
STIX spreadsheet application STIX according to ISO 12217-2 2013 for Sailboat of Length > 6 m
Input data (in yellow cells the necessary input, in blue the data coming from Stab) Hull length excluded bolted on extensions (bowsprit, stem roller, etc...) LH (m) 10,300 Hull width excluded bolted on extensions (cab rails, rub rails, etc …) BH (m) 2,600 Displacement (ISO consider either mMO Minimum Operating condition m (kg) 2952 or mLA Loaded Arrival condition) Length waterplane (to put heel = 0 in Stab) Lwl (m) 8,240 Beam waterplane (to put heel = 0 in Stab) Bwl (m) 2,227 Sail area (Mainsail + fore triangle) As (m2) 43,6 <<< to input Height of sail area centroid (/H0) hCE (m) 5,37 <<< to input Height of center (m) of lateral area below the waterline when the boat hLP (m) 0,586 is upright (/H0) Height of waterline in loading condition (to put heel = 0 in Stab) (m) 0,021 Data coming from the GZ Curve : With Zg (m) With Zg (m) 0,104 0,150 Righting arm at 90° GZ90° (m) 0,283 0,237 First occuring downflooding angle PhiD (deg) 95 95 <<< to input >> Righting arm at downflooding angle (Computed in Stab) GZD (m) 0,226 0,180 Angle of vanishing stability AVS (deg) 113,9 110,3 Area under the GZ curve up to AVS AGZ (m.deg) 36,085 32,560 Computation of the STIX parameters LBS (m) 8,926 8,926 FL 0,959 0,959 (0,75 – 1,25) FDL 0,910 0,910 FB 1,925 1,925 (0,75 – 1,25) FBD 1,035 1,035 FR 1,789 1,498 (0,5 – 1,5) FKR 1,024 0,999 (0,4 – 1,5) FIR 0,925 0,896 (0,5 – 1,0) FWM 1,000 1,000 (0,5 – 1,5) FDS 0,903 0,875 (0,5 – 1,25) FDF 1,056 1,056
>> STIX 25,0 23,9
Design category Cat. A Cat. B Cat. C Cat. D STIX Lower limit 32 23,0 14,0 5
Areas ratio 2,3 1,9
The output is given both for the initial Zg (here 0,104 m) and for the « Other » Zg (here 0,150 m) from the input in the Stab sheet. The result shows that with both Zg the STIX = 25,0 and 23,9 respectively, meaning that the boat can be classify in the Cat. B.
One can also highlight on the influence of PhiD , e.g. ± 3° / 95° : with 92° >>> STIX = 24,6 ; with 95° >>> STIX = 25,0 ; with 98° >>> STIX = 25,4 >>> does not change for the classification in Cat. B.
The Areas ratio, already computed in the Stab sheet, is here just recopied.
Boat V1 / influence of a the extra volume provided by the cabin roof assumed waterproof.
Done with putting Kroof (%B) = 29 (in cell B53), i.e. the value which corresponds to the roof drawing in pages 2 and 3 , >>> : GZ data storage (by copy/special paste) Input new Zg 0,150 Heel (°) Trim (°) GZ (m) GZ (m) 0,00 0,45 -0,001 -0,001 5,00 0,42 0,088 0,084 10,00 0,34 0,171 0,163 15,00 0,20 0,245 0,233 20,00 0,02 0,307 0,292 25,00 -0,19 0,359 0,340 30,00 -0,44 0,403 0,380 35,00 -0,70 0,439 0,413 40,00 -0,97 0,465 0,436 45,00 -1,23 0,480 0,447 50,00 -1,48 0,483 0,448 55,00 -1,69 0,475 0,438 60,00 -1,86 0,460 0,421 65,00 -1,99 0,444 0,402 70,00 -2,09 0,439 0,396 75,00 -2,16 0,433 0,389 80,00 -2,21 0,396 0,350 85,00 -2,23 0,350 0,304 90,00 -2,21 0,304 0,258 95,00 -2,15 0,261 0,215 100,00 -2,07 0,214 0,169 105,00 -1,98 0,167 0,122 110,00 -1,85 0,118 0,075 115,00 -1,71 0,069 0,027 120,00 -1,54 0,022 -0,018 125,00 -1,36 -0,024 -0,062 130,00 -1,17 -0,067 -0,102 135,00 -0,95 -0,105 -0,137 140,00 -0,73 -0,136 -0,166 145,00 -0,50 -0,160 -0,186 150,00 -0,27 -0,172 -0,195 155,00 -0,03 -0,170 -0,190 160,00 0,19 -0,159 -0,175 165,00 0,40 -0,144 -0,156 170,00 0,55 -0,124 -0,132 175,00 0,64 -0,092 -0,096 180,00 0,65 -0,002 -0,002 AVS (°) AVS (°) 122,34 118,00 Areas ratio Areas ratio 5,64 4,24 GZ Curve
Blue : with initial Zg ; Red : with new input Zg Dashed lines : with the cabin roof
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The influence begins at about 70° of heel, increasing the AVS angle and reducing the negative area. Boat V1 / STIX with added a cabin roof
STIX spreadsheet application STIX according to ISO 12217-2 2013 for Sailboat of Length > 6 m
Input data (in yellow cells the necessary input, in blue the data coming from Stab) Hull length excluded bolted on extensions (bowsprit, stem roller, etc...) LH (m) 10,300 Hull width excluded bolted on extensions (cab rails, rub rails, etc …) BH (m) 2,600 Displacement (ISO consider either mMO Minimum Operating condition m (kg) 2952 or mLA Loaded Arrival condition) Length waterplane (to put heel = 0 in Stab) Lwl (m) 8,240 Beam waterplane (to put heel = 0 in Stab) Bwl (m) 2,227 Sail area (Mainsail + fore triangle) As (m2) 43,6 <<< to input Height of sail area centroid (/H0) hCE (m) 5,37 <<< to input Height of center (m) of lateral area below the waterline when the boat hLP (m) 0,586 is upright (/H0) Height of waterline in loading condition (to put heel = 0 in Stab) (m) 0,021 Data coming from the GZ Curve : With Zg (m) With Zg (m) 0,104 0,150 Righting arm at 90° GZ90° (m) 0,304 0,258 First occuring downflooding angle PhiD (deg) 95 95 <<< to input >> Righting arm at downflooding angle (Computed in Stab) GZD (m) 0,261 0,215 Angle of vanishing stability AVS (deg) 122,3 118,0 Area under the GZ curve up to AVS AGZ (m.deg) 37,903 33,941 Computation of the STIX parameters LBS (m) 8,926 8,926 FL 0,959 0,959 (0,75 – 1,25) FDL 0,910 0,910 FB 1,925 1,925 (0,75 – 1,25) FBD 1,035 1,035 FR 1,925 1,635 (0,5 – 1,5) FKR 1,035 1,011 (0,4 – 1,5) FIR 0,993 0,958 (0,5 – 1,0) FWM 1,000 1,000 (0,5 – 1,5) FDS 0,916 0,886 (0,5 – 1,25) FDF 1,056 1,056
>> STIX 26,2 25,0
Design category Cat. A Cat. B Cat. C Cat. D STIX Lower limit 32 23,0 14,0 5
Areas ratio 5,6 4,2
With the initial Zg ( here 0,104 m) With an other Zg (here 0,150 m) Flush deck With roof volume Flush deck With roof volume AVS (°) 113,88 122,34 110,32 118,00 STIX index* 25,0 26,2 23,9 25,0 Areas ratio 2,3 5,6 1,9 4,2 * at constant PhiD which is a bit conservative : for a first downflooding at around 95°, the influence of the roof volume should increase a bit this value.
The most spectacular influence of a cabin roof is for the AVS angle and the areas ratio. Following the Vendée Globe 1996/1997 where several boats with quasi flat deck were rolled upside down and unfortunately remained stable in this position, the Imoca class added the Aeras ratio > 5 criteria in their rules. That led to new design of the deck & roof volumes in oder to reduce a lot this stability upside down, so that the energy brought by the waves can be sufficient to upright again the boat after such a capsize event. S30, inspired by the S30 / Knud Reimers
Loa 12,50 m ; Lwl 9,9 m ; B 2,50 m ; Draft 1,55 m ; Light weight : 4229 kg ; Ballast : 1511 kg
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SA (m2) ZCE (m) Zdeck (m) Zmast (m) Main (m2) Spi (m2) ZCE spi (m) 42,69 5,26 0,87 13,18 24,58 63,37 6,30
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-300 S30 / Introduction of a load and its position Xg, Zg, Yg :
Mass spreadsheet with input of a load Mass Xg Zg Yg (kg) (m) (m) (m) Boat light weight (kg) 4228,76 4,686 0,006 0 Data to enter Load (kg) 300,00 2,50 0,90 0,00 Crew at center yellow cells 0,90 0,00 Crew sit windward Total >>> Mass (kg) 4528,76 4,541 0,065 0,000 Crew at center Disp. (m3) 4,41830 0,065 0,000 Crew sit windward
S30 / Computation of the GZ ( with a flush deck , Kroof = 0)
GZ data storage (by copy/special paste) Input new Zg 0,089 Heel (°) Trim (°) GZ (m) GZ (m) 0,00 0,65 -0,002 -0,002 5,00 0,64 0,048 0,046 10,00 0,60 0,097 0,093 15,00 0,55 0,144 0,137 20,00 0,48 0,187 0,179 25,00 0,39 0,227 0,217 30,00 0,28 0,264 0,252 35,00 0,16 0,297 0,284 40,00 0,05 0,323 0,307 45,00 -0,07 0,338 0,321 50,00 -0,18 0,343 0,325 55,00 -0,27 0,341 0,321 60,00 -0,36 0,333 0,312 65,00 -0,41 0,321 0,299 70,00 -0,44 0,317 0,295 75,00 -0,46 0,340 0,317 80,00 -0,46 0,333 0,310 85,00 -0,46 0,295 0,271 90,00 -0,45 0,254 0,230 95,00 -0,42 0,209 0,185 100,00 -0,39 0,163 0,139 105,00 -0,34 0,115 0,092 110,00 -0,29 0,066 0,044 115,00 -0,22 0,018 -0,004 120,00 -0,14 -0,030 -0,051 125,00 -0,06 -0,076 -0,096 130,00 0,02 -0,120 -0,139 135,00 0,12 -0,161 -0,178 140,00 0,20 -0,197 -0,212 145,00 0,29 -0,227 -0,241 150,00 0,37 -0,250 -0,262 155,00 0,44 -0,263 -0,273 160,00 0,50 -0,261 -0,269 165,00 0,53 -0,239 -0,245 170,00 0,55 -0,187 -0,191 175,00 0,56 -0,098 -0,100 180,00 0,56 -0,002 -0,002 AVS (°) AVS (°) 116,87 114,60 Areas ratio Areas ratio 2,55 2,21 GZ curve
Blue : with initial Zg ; Red : with new input Zg
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Heel (°)
One can see the influence of the progressive emergence of the keel wing volume on the GZ curve, occuring between ~ 65° and 80° heel angles, the GZ is boost up >>> e.g. configuration at 70° :
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Data to enter : yellow cell Results Heel (°) 70 Disp. (m3) 4,41830 / Disp. (m3) 4,41830 > Height (cm) 32,3790 Xc heel (m) 4,541 / Xg (m) 4,541 > Trim (°) -0,435 Yc heel (m) -0,378 Yg heel (m) -0,061 Zc heel (m) -0,243 > GZ (m) 0,317 Sw heel (m2) 23,91 RM (kN.m) 14,100 Bwl heel (m) 1,30 FB mini (cm) -61,4 Xf (Heel) – Xf (0°) (%Lwl) 0,96 Obliquity (°) -0,32 Check % convergence 0,00 : Disp 0,00 : X Kvol. : 0,618
>>> The volume ratio of the keel wing still in the water is given by Kvol, here 0,618 S30 / STIX (with assuming PhiD = 95° for a first downflooding)
STIX spreadsheet application STIX according to ISO 12217-2 2013 for Sailboat of Length > 6 m
Input data (in yellow cells the necessary input, in blue the data coming from Stab) Hull length excluded bolted on extensions (bowsprit, stem roller, etc...) LH (m) 12,500 Hull width excluded bolted on extensions (cab rails, rub rails, etc …) BH (m) 2,502 Displacement (ISO consider either mMO Minimum Operating condition m (kg) 4529 or mLA Loaded Arrival condition) Length waterplane (to put heel = 0 in Stab) Lwl (m) 10,130 Beam waterplane (to put heel = 0 in Stab) Bwl (m) 2,156 Sail area (Mainsail + fore triangle) As (m2) 42,7 <<< to input Height of sail area centroid (/H0) hCE (m) 5,26 <<< to input Height of center (m) of lateral area below the waterline when the boat hLP (m) 0,660 is upright (/H0) Height of waterline in loading condition (to put heel = 0 in Stab) (m) 0,017 Data coming from the GZ Curve : With Zg (m) With Zg (m) 0,065 0,089 Righting arm at 90° GZ90° (m) 0,254 0,230 First occuring downflooding angle PhiD (deg) 95 95 <<< to input >> Righting arm at downflooding angle (Computed in Stab) GZD (m) 0,209 0,185 Angle of vanishing stability AVS (deg) 116,9 114,6 Area under the GZ curve up to AVS AGZ (m.deg) 26,817 24,762 Computation of the STIX parameters LBS (m) 10,920 10,920 FL 0,999 0,999 (0,75 – 1,25) FDL 0,901 0,901 FB 1,606 1,606 (0,75 – 1,25) FBD 1,038 1,038 FR 2,566 2,323 (0,5 – 1,5) FKR 1,089 1,069 (0,4 – 1,5) FIR 0,957 0,938 (0,5 – 1,0) FWM 1,000 1,000 (0,5 – 1,5) FDS 0,802 0,783 (0,5 – 1,25) FDF 1,056 1,056
>> STIX 28,7 27,8
Design category Cat. A Cat. B Cat. C Cat. D STIX Lower limit 32 23,0 14,0 5
Areas ratio 2,6 2,2
>>> In both cases of Zg, the STIX index is largely over 23, putting the S30 in the Cat. B S30 / Computation of the GZ with added a cabin roof (here with Kroof (%B) = 29) :
GZ data storage (by copy/special paste) Input new Zg 0,089 Heel (°) Trim (°) GZ (m) GZ (m) 0,00 0,65 -0,002 -0,002 5,00 0,64 0,048 0,046 10,00 0,60 0,097 0,093 15,00 0,55 0,144 0,137 20,00 0,48 0,187 0,179 25,00 0,39 0,227 0,217 30,00 0,28 0,264 0,252 35,00 0,16 0,297 0,284 40,00 0,05 0,323 0,307 45,00 -0,07 0,338 0,321 50,00 -0,18 0,343 0,325 55,00 -0,27 0,341 0,321 60,00 -0,36 0,333 0,313 65,00 -0,42 0,326 0,304 70,00 -0,44 0,329 0,307 75,00 -0,44 0,362 0,339 80,00 -0,45 0,359 0,335 85,00 -0,43 0,332 0,308 90,00 -0,40 0,300 0,276 95,00 -0,36 0,265 0,241 100,00 -0,31 0,227 0,203 105,00 -0,25 0,186 0,163 110,00 -0,18 0,145 0,122 115,00 -0,10 0,102 0,081 120,00 -0,01 0,061 0,040 125,00 0,08 0,020 0,000 130,00 0,17 -0,018 -0,037 135,00 0,27 -0,053 -0,070 140,00 0,38 -0,082 -0,098 145,00 0,48 -0,105 -0,119 150,00 0,58 -0,118 -0,130 155,00 0,68 -0,126 -0,136 160,00 0,76 -0,128 -0,137 165,00 0,82 -0,126 -0,132 170,00 0,85 -0,115 -0,120 175,00 0,85 -0,084 -0,086 180,00 0,85 -0,003 -0,003 AVS (°) AVS (°) 127,61 125,07 Areas ratio Areas ratio 6,27 5,18 GZ Curve
Blue : with initial Zg ; Red : with new input Zg Dashed lines : with the cabin roof
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The influence begins at about 60° of heel, increasing the AVS angle and reducing the negative area. S30 / STIX (with the GZ curve computed with the adding of a roof volume)
STIX spreadsheet application STIX according to ISO 12217-2 2013 for Sailboat of Length > 6 m
Input data (in yellow cells the necessary input, in blue the data coming from Stab) Hull length excluded bolted on extensions (bowsprit, stem roller, etc...) LH (m) 12,500 Hull width excluded bolted on extensions (cab rails, rub rails, etc …) BH (m) 2,502 Displacement (ISO consider either mMO Minimum Operating condition m (kg) 4529 or mLA Loaded Arrival condition) Length waterplane (to put heel = 0 in Stab) Lwl (m) 10,130 Beam waterplane (to put heel = 0 in Stab) Bwl (m) 2,156 Sail area (Mainsail + fore triangle) As (m2) 42,7 <<< to input Height of sail area centroid (/H0) hCE (m) 5,26 <<< to input Height of center (m) of lateral area below the waterline when the boat hLP (m) 0,660 is upright (/H0) Height of waterline in loading condition (to put heel = 0 in Stab) (m) 0,017 Data coming from the GZ Curve : With Zg (m) With Zg (m) 0,065 0,089 Righting arm at 90° GZ90° (m) 0,300 0,276 First occuring downflooding angle PhiD (deg) 95 95 <<< to input >> Righting arm at downflooding angle (Computed in Stab) GZD (m) 0,265 0,241 Angle of vanishing stability AVS (deg) 127,6 125,1 Area under the GZ curve up to AVS AGZ (m.deg) 29,723 27,560 Computation of the STIX parameters LBS (m) 10,920 10,920 FL 0,999 0,999 (0,75 – 1,25) FDL 0,901 0,901 FB 1,606 1,606 (0,75 – 1,25) FBD 1,038 1,038 FR 3,039 2,796 (0,5 – 1,5) FKR 1,128 1,108 (0,4 – 1,5) FIR 1,045 1,024 (0,5 – 1,0) FWM 1,000 1,000 (0,5 – 1,5) FDS 0,827 0,809 (0,5 – 1,25) FDF 1,056 1,056
>> STIX 31,0 30,0
Design category Cat. A Cat. B Cat. C Cat. D STIX Lower limit 32 23,0 14,0 5
Areas ratio 6,3 5,2
With the initial Zg (here 0,065 m) With an other Zg (here 0,089 m) Flush deck With roof volume Flush deck With roof volume AVS (°) 116,87 127,61 114,60 125,07 STIX index 28,7 31,0 27,8 30,0 Areas ratio 2,6 6,3 2,2 5,2 Blue Water 39, inspired by Corbin 39 / Robert Dufour – Marius Corbin
Loa 11,46 m ; Lwl 9,72 m ; B 3,71 m ; Draft 1,68 m ; Light weight : 10741 kg ; Ballast : 4073 kg
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SA (m2) ZCE (m) Zdeck (m) Zmast (m) Main (m2) Spi (m2) ZCE spi (m) 85,78 7,25 1,52 16,48 45,02 95,61 8,26
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Mass spreadsheet with input of a load Mass Xg Zg Yg (kg) (m) (m) (m) Boat light weight (kg) 10740,93 4,676 0,019 0 Data to enter Load (kg) 3259,07 3,895 0,10 0,00 Crew at center yellow cells 0,10 0,00 Crew sit windward Total >>> Mass (kg) 14000,00 4,494 0,038 0,000 Crew at center Disp. (m3) 13,65854 0,038 0,000 Crew sit windward
Blue Water 39 / Computation of the GZ (with a flush deck , Kroof = 0)
GZ data storage (by copy/special paste) Input new Zg 0,052 Heel (°) Trim (°) GZ (m) GZ (m) 0,00 0,00 0,000 0,000 5,00 -0,02 0,096 0,095 10,00 -0,05 0,188 0,185 15,00 -0,12 0,273 0,269 20,00 -0,21 0,350 0,345 25,00 -0,33 0,419 0,413 30,00 -0,47 0,481 0,474 35,00 -0,62 0,538 0,530 40,00 -0,79 0,589 0,580 45,00 -0,96 0,627 0,617 50,00 -1,13 0,650 0,639 55,00 -1,30 0,662 0,650 60,00 -1,45 0,665 0,653 65,00 -1,55 0,670 0,657 70,00 -1,60 0,685 0,672 75,00 -1,58 0,699 0,686 80,00 -1,56 0,664 0,651 85,00 -1,51 0,610 0,596 90,00 -1,43 0,548 0,534 95,00 -1,33 0,480 0,467 100,00 -1,20 0,409 0,395 105,00 -1,05 0,333 0,320 110,00 -0,89 0,256 0,243 115,00 -0,71 0,177 0,165 120,00 -0,51 0,099 0,087 125,00 -0,32 0,022 0,011 130,00 -0,10 -0,052 -0,062 135,00 0,11 -0,120 -0,130 140,00 0,32 -0,182 -0,191 145,00 0,51 -0,235 -0,243 150,00 0,69 -0,275 -0,282 155,00 0,85 -0,297 -0,303 160,00 0,95 -0,294 -0,299 165,00 1,01 -0,258 -0,261 170,00 1,04 -0,180 -0,182 175,00 1,06 -0,089 -0,090 180,00 1,07 -0,001 -0,001 AVS (°) AVS (°) 126,50 125,73 Areas ratio Areas ratio 5,67 5,36 GZ curve
Blue : with initial Zg ; Red : with new input Zg
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STIX spreadsheet application STIX according to ISO 12217-2 2013 for Sailboat of Length > 6 m
Input data (in yellow cells the necessary input, in blue the data coming from Stab) Hull length excluded bolted on extensions (bowsprit, stem roller, etc...) LH (m) 11,460 Hull width excluded bolted on extensions (cab rails, rub rails, etc …) BH (m) 3,710 Displacement (ISO consider either mMO Minimum Operating condition m (kg) 14000 or mLA Loaded Arrival condition) Length waterplane (to put heel = 0 in Stab) Lwl (m) 10,047 Beam waterplane (to put heel = 0 in Stab) Bwl (m) 3,526 Sail area (Mainsail + fore triangle) As (m2) 85,8 <<< to input Height of sail area centroid (/H0) hCE (m) 7,25 <<< to input Height of center (m) of lateral area below the waterline when the boat hLP (m) 0,843 is upright (/H0) Height of waterline in loading condition (to put heel = 0 in Stab) (m) 0,132 Data coming from the GZ Curve : With Zg (m) With Zg (m) 0,038 0,052 Righting arm at 90° GZ90° (m) 0,548 0,534 First occuring downflooding angle PhiD (deg) 95 95 <<< to input >> Righting arm at downflooding angle (Computed in Stab) GZD (m) 0,480 0,467 Angle of vanishing stability AVS (deg) 126,5 125,7 Area under the GZ curve up to AVS AGZ (m.deg) 55,892 54,641 Computation of the STIX parameters LBS (m) 10,518 10,518 FL 0,991 0,991 (0,75 – 1,25) FDL 1,148 1,148 FB 1,635 1,635 (0,75 – 1,25) FBD 1,090 1,090 FR 6,282 6,122 (0,5 – 1,5) FKR 1,398 1,385 (0,4 – 1,5) FIR 1,088 1,082 (0,5 – 1,0) FWM 1,000 1,000 (0,5 – 1,5) FDS 1,013 1,006 (0,5 – 1,25) FDF 1,056 1,056
>> STIX 43,8 43,3
Design category Cat. A Cat. B Cat. C Cat. D STIX Lower limit 32 23,0 14,0 5
Areas ratio 5,7 5,4
With a STIX index of 43,8 (or 43,3 if Zg is higher than expected), Blue Water 39 is clearly in the Cat. A. Moreover, the Areas ratio 5,7 or 5,4 are > 5 with both Zg. F3, inspired by Beneteau Figaro III / VPLP
Loa 9,75 m ; Lwl 9,40 m ; B 3,47 m ; Draft 2,50 m ; Light weight : 3257 kg ; Ballast : 1243 kg
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-300 -300 Sailplan : SA (m2) ZCE (m) Zdeck (m) Zmast (m) Main (m2) Spi (m2) ZCE spi (m) 57,72 6,02 1,09 14,48 30,84 94,06 7,00
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Mass spreadsheet with input of a load Mass Xg Zg Yg (kg) (m) (m) (m) Boat light weight (kg) 3256,88 4,236 0,226 0 Data to enter Load (kg) 160,00 2,00 1,00 0,00 Crew at center yellow cells 1,00 0,00 Crew sit windward Total >>> Mass (kg) 3416,88 4,132 0,263 0,000 Crew at center Disp. (m3) 3,33354 0,263 0,000 Crew sit windward
F3 / Computation of the GZ (with a flush deck , Kroof = 0)
GZ data storage (by copy/special paste) Input new Zg 0,300 Heel (°) Trim (°) GZ (m) GZ (m) 0,00 0,36 -0,001 -0,001 5,00 0,27 0,182 0,179 10,00 0,02 0,348 0,342 15,00 -0,35 0,486 0,477 20,00 -0,82 0,596 0,583 25,00 -1,32 0,670 0,654 30,00 -1,81 0,713 0,694 35,00 -2,28 0,732 0,711 40,00 -2,74 0,732 0,708 45,00 -3,16 0,716 0,689 50,00 -3,57 0,695 0,667 55,00 -3,96 0,668 0,637 60,00 -4,30 0,634 0,601 65,00 -4,59 0,596 0,562 70,00 -4,82 0,578 0,543 75,00 -4,99 0,537 0,501 80,00 -5,13 0,462 0,426 85,00 -5,19 0,383 0,346 90,00 -5,20 0,299 0,261 95,00 -5,16 0,211 0,174 100,00 -5,04 0,121 0,084 105,00 -4,87 0,030 -0,006 110,00 -4,66 -0,062 -0,097 115,00 -4,39 -0,153 -0,186 120,00 -4,06 -0,242 -0,274 125,00 -3,69 -0,329 -0,359 130,00 -3,29 -0,411 -0,439 135,00 -2,86 -0,488 -0,514 140,00 -2,39 -0,557 -0,581 145,00 -1,90 -0,616 -0,638 150,00 -1,40 -0,664 -0,682 155,00 -0,90 -0,696 -0,712 160,00 -0,44 -0,712 -0,725 165,00 0,00 -0,691 -0,700 170,00 0,39 -0,607 -0,613 175,00 0,69 -0,410 -0,413 180,00 0,78 -0,003 -0,003 AVS (°) AVS (°) 106,63 104,66 Areas ratio Areas ratio 1,57 1,42 GZ curve
Blue : with initial Zg ; Red : with new input Zg
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Heel (°) F3 / Some typical heeling configurations :
At heel 15° >>> GZ = 0,486 m
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At heel 30° >>> GZ = 0,713 m
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At heel 60° >>> GZ = 0,634 m
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At heel 90° >>> GZ = 0,299 m
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-100 -100 At heel 106,63° >>> GZ = 0,000 m AVS Angle of Vanishing Stability
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At heel 135° >>> GZ = - 0,488 m
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STIX spreadsheet application STIX according to ISO 12217-2 2013 for Sailboat of Length > 6 m
Input data (in yellow cells the necessary input, in blue the data coming from Stab) Hull length excluded bolted on extensions (bowsprit, stem roller, etc...) LH (m) 9,750 Hull width excluded bolted on extensions (cab rails, rub rails, etc …) BH (m) 3,470 Displacement (ISO consider either mMO Minimum Operating condition m (kg) 3417 or mLA Loaded Arrival condition) Length waterplane (to put heel = 0 in Stab) Lwl (m) 9,312 Beam waterplane (to put heel = 0 in Stab) Bwl (m) 2,733 Sail area (Mainsail + fore triangle) As (m2) 57,7 <<< to input Height of sail area centroid (/H0) hCE (m) 6,02 <<< to input Height of center (m) of lateral area below the waterline when the boat hLP (m) 0,769 is upright (/H0) Height of waterline in loading condition (to put heel = 0 in Stab) (m) 0,007 Data coming from the GZ Curve : With Zg (m) With Zg (m) 0,263 0,300 Righting arm at 90° GZ90° (m) 0,299 0,261 First occuring downflooding angle PhiD (deg) 95 95 <<< to input >> Righting arm at downflooding angle (Computed in Stab) GZD (m) 0,211 0,174 Angle of vanishing stability AVS (deg) 106,6 104,7 Area under the GZ curve up to AVS AGZ (m.deg) 51,869 48,979 Computation of the STIX parameters LBS (m) 9,458 9,458 FL 0,970 0,970 (0,75 – 1,25) FDL 0,910 0,910 FB 2,447 2,447 (0,75 – 1,25) FBD 0,846 0,846 FR 1,469 1,285 (0,5 – 1,5) FKR 0,989 0,928 (0,4 – 1,5) FIR 0,868 0,852 (0,5 – 1,0) FWM 1,000 1,000 (0,5 – 1,5) FDS 1,015 0,998 (0,5 – 1,25) FDF 1,056 1,056
>> STIX 23,8 22,6
Design category Cat. A Cat. B Cat. C Cat. D STIX Lower limit 32 23,0 14,0 5
Areas ratio 1,6 1,4
Here, the slight difference of STIX (23,8 and 22,6) for the 2 Zg (0,263 m and 0,300 m) can lead to 2 different classification, Cat. A and Cat. B. It should also be noted that the areas ratio is quite low, this boat without a proeminent enough roof can be too stable upside down.