Shipboard routing assistance : Decision making support for operation of container ships in heavy seas. Discussion

As container ships become larger and respond less directly to the seaway it becomes more difficult for the ship officers to correctly judge the seas and to consistently make the right decisions for a safe operation of the vessel. Highly stacked containers on deck in front of the bridge further contribute to a distancing of the officers from the sea. SRA, Shipboard Routing Assistance, combines performance-monitoring of a ship at sea with information on the weather and the sea to supply active routing assistance to the navigating personnel. The objective of SRA focuses on the prevention of dangerous conditions with cargo loss and possibly structural damage to the ship when operating in bad weather. The fundamental innovation of SRA as compared to the classical ship response monitoring systems concerns the continuous shipboard measurement of the seaway surrounding the ship in terms of seaway spectra prepared at regular intervals and the corresponding response calculations with the aim to recognize situations potentially dangerous to ship and cargo. The seaway spectra are derived from measurements with the ship's own radar system. Together with pre-calculated ship response transfer functions predictions of ship motions and hull girder loads are derived for the actual sea conditions onboard. The results are permanently updated and displayed on a monitor in the wheelhouse. Active routing planning is possible by combining the system with weather forecasts, enabling the ship master to prepare for or to avoid critical situations ahead and to minimize any risks. The system is simple and easy to use. It has been successfully installed within pilot projects on a Panamax and on a Post-Panamax container ship. Within those pilot projects additional, independent strain gages and ship motion sensors were installed onboard to validate the semi-empirical SRA predictions. Results from these two pilot installations confirm the effectiveness of the system. They are discussed in the paper together with the validations. The performance and possibilities of the SRA system as a decision making support tool on board is described. A training version of SRA has been developed for the training and familiarization of navigating personnel before going out to sea. Finally the benefits of such a system on board for the ship operator, for the ship owner and also for the classification society are being discussed.