Examination of the intact stability and the seakeeping behaviour

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2 Theory Figure 2.1: Calculation model for the RAO determination 2.1.1.2 Roll radius of inertia and roll period Before calculating the respective RAO sets, the roll radius of inertia of the ship as well as the roll period are calculated. The roll period applies for still water condition and small rolling angles. For the roll radius of inertia two values are calculated based on the ship's weight with and without the inuence of section added masses, which consider the inuence of the water, surrounding the ship's hull. Normally the roll radius of inertia with the inuence of section added masses shall not exceed values of about 0.45 B for container vessels. For the examined vessels in ballast arrival loading condition, the dry roll radius of inertia reaches a value between 0.33 B ... 0.37 B . The wet roll radius of inertia reaches values between 0.40 B ... 0.42 B. So the used models are reasonable. The estimated roll periods reach values between 9.5 s ... 11 s. 2.1.1.3 Roll damping It can be stated that the damping of a ship's roll motion is relatively small compared to e.g. the damping of the heave or pitch motion. Therefore large roll angles may occur in a resonance condition. This indicates that the assumption of a correct roll damping is mandatory. The direct, theoretical calculation of the roll damping is not possible until now. Only the damping due to wave radiation can be calculated with potential theory methods. But there are many other highly nonlinear and also viscous eects to consider. 6
2.1 Description of the utilised seakeeping simulation method For this reason Blume [9] developed roll damping coecients, based on practical experiments of ships in model scale. With these empirical coecients the roll damping can be corrected to a more realistic value. At this the correction includes also the damping inuence of the bilge keels. The roll damping in E4ROLLS is considered with these coecients of similar ships. 2.1.1.4 Calculation settings The calculations for higher speeds (v > 18 kn) and short wave lengths lead to problems for the surge, sway and yaw motion RAOs, which are reaching disproportionately high values or become singular. Consequently the problematic short wave lengths are excluded for higher speeds. 7
Page 1: Dezember 2010 SCHRIFTENREIHE SCHIFF
Page 5: 1st Examiner: Prof. Dr.-Ing. Stefan
Page 9 and 10: Contents List of Figures List of Ta
Page 11 and 12: Contents A.14 Vessel No. 14 . . . .
Page 13 and 14: List of Figures 2.1 Calculation mod
Page 15 and 16: List of Tables 3.1 Accident situati
Page 17 and 18: Nomenclature Symbol Unit Meaning A
Page 19 and 20: 1 Introduction In the years 2008/20
Page 21 and 22: 1.2 Following objectives for the di
Page 23: 2 Theory 2.1 Description of the uti
Page 27 and 28: 2.1 Description of the utilised sea
Page 29 and 30: 2.2 Environmental conditions period
Page 31 and 32: 3 Data input The thesis is written
Page 33 and 34: 3.6 Free surface correction 3.6 Fre
Page 35 and 36: 3.10 Bridge height 3.10 Bridge heig
Page 37 and 38: 4 Examination For each vessel the s
Page 39 and 40: 4.2 Vessel No. 02 4.2 Vessel No. 02
Page 41 and 42: 4.3 Vessel No. 03 ˆ The documented
Page 43 and 44: 4.5 Vessel No. 05 accident situatio
Page 45 and 46: 4.6 Vessel No. 06 4.6 Vessel No. 06
Page 47 and 48: 4.7 Vessel No. 07 ˆ The stability
Page 49 and 50: 4.9 Vessel No. 09 Figure 4.16: Tran
Page 51 and 52: 4.10 Vessel No. 10 4.10 Vessel No.
Page 53 and 54: 4.11 Vessel No. 11 ˆ The limiting
Page 55 and 56: 4.13 Vessel No. 13 Figure 4.24: Tra
Page 61 and 62: 5 Evaluation Based on the determina
Page 63 and 64: 5.3 Recommendations accelerations s
Page 65 and 66: 6 Detailed examination The evaluati
Page 67 and 68: 6.1 Variation of the GM values acce
Page 69 and 70: 6.2 Rolling behavior of the large v
Page 75 and 76:
7 Conclusions Summing up the result
Page 77 and 78:
A Vessel data A.1 Vessel No. 01 Tab
Page 79 and 80:
A.3 Vessel No. 03 A.3 Vessel No. 03
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
A.11 Vessel No. 11 A.11 Vessel No.
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
B Variation of the bilge keel area
Page 95 and 96:
C Variation of the ship's speed 16
Page 97:
Bibliography [1] BSU; Federal Burea
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Examination of the intact stability and the seakeeping behaviour

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