Trans RINA, Vol 152, Part A4, Intl J Maritime Eng, Oct-Dec 2010


KG to the dynamic aspects of the motion after damage, as well as the final equilibrium value.


Note that for run P1_R08, with a KG value of 163 mm, the model had an initial heel angle of about 0.7º to starboard, which was assumed to be due to a slight error in the transverse centre of gravity position. This is as a result of the internal video camera accidentally shifting position slightly just prior to the run.


5.2(b) Water levels in compartments


The initial water level in the starboard tank on the 2nd Deck (2Centre-S12) is higher when the KG value was higher, as the higher KG values result in greater initial heel angles, Figure 16. This probe is fully submerged upon reaching the equilibrium position for all values of KG.


For the lower KG value the model did not heel to port, and consequently the level of water during the run in the two compartments on the 2nd deck on the port side (2Aft-S11 and 2Centre S15) was significantly lower than for the other runs, as seen in Figures 17 and 18.


For both the lower KG values water did not reach the wave probe at the rear of the aft compartment on the starboard side on the 2nd deck (1Aft-S17).


The equilibrium heel angle and the maximum port heel angle (intermediate heel angle) are plotted as functions of KG in Figure 19. The run with the KG value of 163 mm had an initial equilibrium heel angle of 0.7º to starboard. Therefore, the results in Figure 18 for this run were adjusted by 0.7º to give the difference in heel angle from the initial condition. It is assumed that this will give a reasonable estimate of the heel angles that would have been obtained had the model been ballasted correctly.


As can be seen, both the equilibrium heel angle and the maximum angle to port were greater when the KG value was greater.


6. CONCLUDING COMMENTS


A series of experiments has been conducted in calm water on a 3.268 metre long model of a generic destroyer hull form to generate data to further validate the flooding module in a non-linear time domain ship motions code.


With the model initially stationary, a rapid damage event was generated, and the global motions measured, along with the water levels in some of the internal compartments, as functions of time.


Immediately after the damage occurred the model rolled to starboard (towards the damage). It then rolled


to port (away from the damage) before eventually returning to starboard and settling at its equilibrium value. In all the tests conducted the equilibrium heel angle was less than that reached during the initial roll to starboard.


Five runs were conducted to investigate repeatability. The initial motion, and the initial rate of water level rise in the compartments were very similar in all these runs. However, the rate of roll motion and water levels in the compartments differed noticeably during the phase between the initial maximum roll angle to starboard, and the final equilibrium heel angle.


The final


equilibrium heel angle and final water levels in the compartments were similar in all these runs.


Tests were conducted at four different values of vertical centre of gravity. From these the value of the initial roll angle to starboard, the subsequent intermediate roll angle to port, and the final equilibrium heel angle, as functions of vertical centre of gravity, were determined. As expected, when the centre of gravity is higher these heel angles were higher.


7. ACKNOWLEDGEMENTS


The authors acknowledge the contributions from Mr Egbert Ypma and Dr Frans van Walree of MARIN.


8. 1.


REFERENCES


Macfarlane, G.J, and Renilson, M.R., 2010, Damage stability CRN destroyer, Phase 1. AMC Report


prepared 2. 3. Research Navies, Report CRN_Phase1_Report_Rev2, September 2010.


Qualisys 2008, Qualisys Track Manager - User Manual, Version 2.1.4, November 2008, Qualisys AB.


Turner, T., Ypma, E., Macfarlane, G.J. and Renilson, M.R., 2010, The development and application of a damage dynamic stability modelling capability for naval


vessels,


Proceedings of the Pacific 2010 International Maritime


Conference, January 2010. 4.


Ypma, E. and Turner, T., 2010, An approach to the validation of ship flooding simulation models, Proceedings of the 11th International Ship Stability Workshop, Wageningen, The Netherlands, June 2010.


Sydney, Australia,


for Cooperative No.


A-212


©2010: The Royal Institution of Naval Architects


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