Time-domain simulation of the maneuvering performance of ships in regular waves and shallow water

The IMO's Second Generation of Intact Stability Criteria (SGISC) have brought the manoeuvring performance of ships in waves to the spotlight of the research community. A very interesting case arises when the vessel's manoeuvrability is affected by shallow water as well. As this instance is rather common closer to shore and in the proximity of ports, any degradation of the vessel's ability to execute the commanded manoeuvres may give rise to safety concerns. The authors present herein a novel hybrid methodology that captures such changes in the ship's manoeuvring performance. It accounts for the influence of both the first and second-order wave forces, as well as on the calm water-related contributions. This hybrid seakeeping and manoeuvring methodology has been programmed into the time-domain simulation software ELIGMOS and it is tested with the S-175 container ship, investigating the impact on her turning circle manoeuvres in long regular waves (λ/L=1.0) at a Froude number of 0.15 and various under keel clearance values. The steady drift forces in shallow water have been calculated using a near-field methodology, embedded in the NEWDRIFT 3D-panel code. Using Ankudinov's formulae, the impact of shallow water on the manoeuvring derivatives has been captured. The authors present analytically the results and discuss their findings.