Surendran Sankunny

Container ships move at a higher speed compared to other merchant ship types. A fin attached to the ship hull proves to be more efficient in controlling the moving ship. However, such attachments on the naked hull attract additional problems such as slamming, requirement of continuous maintenance, etc. The main objective of this study is to find the influence of fin action at various angles of attack with the incoming flow and recommend the best possible fin position for the least resistance. While experiments were performed for different angles of attacks of the fin with respect to the flow, a reduction in resistance was observed for an Fn range of 0.13–0.26. The fin was fitted at the lowest possible location of the hull surface at the bow part of the ship. Experimental investigation was done using model tests in a towing tank to determine the resistance of a scaled down model and it was compared with computer simulation. The interaction of a bow fin fitted to a container ship with its own generated and encountering waves are discussed in this paper. It was observed that at certain angles of attack of the fins favourable resistance characteristics were observed. Modifications from the expected resistance due to fin effect are paid attention in this study. Various resistance values for different angles of attack of the fin were compared and an angle of attack of 5° is found to be the best.

Control devices are selected in the preliminary design stage of any large platforms. This is true for deciding fin area for roll/pitch control of moving platform and thruster sizes and numbers for maneuvering assistance in the case of very low speed conditions. For moored platform the excursions are to be determined to activate the thruster system to reduce the line tension. In the case of a drill ship with moonpool there are some additional parameters of interaction. To some extent the parameters can be contained by optimizing the size and shapes of moon pools on board ships. The dynamics of a moored platform fitted with moon pool are determined here. Such responses are necessary to arrive at the actual sizes and numbers of thrusters to keep the vessel within the tolerances of excursion for ease and accurate operations. © IFAC.