Application of the IMO standard manoeuvres procedure for pod-driven ships

Abstract

International Maritime Organisation (IMO) in the resolution MSC.137(76) Standards for Ship manoeuvrability presents the manoeuvring criteria that has to be satisfied by majority of seagoing ships. Together with the criteria, procedures for carrying out the manoeuvring tests are also presented. They however do not correspond directly to ships with non-conventional steering-propulsion devices, like pod drives. IMO is aware of this shortcoming and permits the use of comparative steering angles to the rudder angles specified by the resolution. To address this problem, a set of model tests has been carried out. Experiments with free-sailing manned model of a pod-driven gas carrier have been carried out to check the satisfaction of IMO criteria with systematically varying pod deflection angles. Results of the research show, that for tested pod-driven gas carrier, IMO manoeuvring criteria on turning circle are satisfied for much smaller deflection angles than recommended by IMO. Therefore a conclusion is made, that although the IMO manoeuvring criteria are valid for pod-driven ships and can be applied directly, the procedure for carrying out especially turning circle tests might be for pod-driven ships reconsidered.