SUB-COMMITTEE ON STABILITY AND LOAD LINES AND ON ...

Ref.: 391/09 and 520/09
BSU
Bundesstelle für Seeunfalluntersuchung
Federal Bureau of Maritime Casualty Investigation
Figure 18: Model for determining the linear transfer function
To calculate the mass moments of inertia of the empty vessel, the longitudinal grid
was used differentiated by the bending moments. Consequently, a roll inertia radius
was determined for the CCNI GUAYAS of 0.39 x breadth when in dry condition
without the proportion of hydrodynamic masses and 0.44 x breadth with the
hydrodynamic proportion. These values are feasible due to the distribution of mass
and especially the cranes on deck. This gives a roll period in smooth water of about
10.7 s, which, due to the lever arm characteristics of the vessel, is valid up to about
20° and the roll period then increases above 20°.
The roll angle on board is not recorded on the voyage data recorder, or otherwise.
Only a non-calibrated inclinometer is available on the bridge. The information given
by the crew that roll angles of 35° were present was calculated and reviewed for
various situations. Significant wave periods of 9.5 s, 9.0 s and 8.5 s were used for the
calculation; these correspond to the range of swell conditions on the day of the
accident specified by the DWD. To being with, a calculation was made of the
conditions under which roll angles of 35° would have occurred at a speed of less than
7 kts.
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