Examination of the intact stability and the seakeeping behaviour

6 Detailed examination
this vessel by e.g. lling ballast water in tanks in low positions. When reducing the GM of the
ballast arrival loading condition, the transversal accelerations increase signicantly up to 10 m /s 2
for a GM around 8.5 m. Then they go down again to uncritical accelerations around 2 m /s 2 .
Mentionable is the fact, that the accident of the Chicago Express occurred in a loading
condition with the same GM = 8.54 m. (refer to BSU report [1]).
Table 6.3: Stability data for the large vessel
Ballast arrival loading
Value Unit
condition
KM 25.64 [m]
KG 13.24 [m]
GM solid 12.40 [m]
Light ship Value Unit
vcg LSW 15.62 [m]
16
14
Maximum transverse acceleration on the bridge [m/s 2 ]
12
10
8
6
4
2
Ballast arrival loading condition
0
2 4 6 8 10 12 14 16
GM solid [m]
Accident situation 1 Accident situation 2 Accident situation 3
Figure 6.3: Chicago Express in ballast arrival oating condition: Variation of GM solid
6.1.4 Comparison of the simulation results
In gure 6.4 the curves of the three vessels are compared for the accident situation 1. For the
other accident situations, the curve shape is comparable. It can be identied, that each vessel has
a unique critical condition, where an exciting seaway in combination with the ship's hull form,
the ship's trim and the GM value, result in very high transversal accelerations on the bridge.
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