Hideo Yabuki

A Study on the Propulsion Performance in the Actual Sea by means of Full-scale Experiments

The International Maritime Organization (IMO) has adopted Energy Efficiency Design Index (EEDI), Ship Energy Efficiency Management Plan (SEEMP) and Energy Efficiency Operational Indicator (EEOI) in order to reduce greenhouse gas (GHG) emissions from international shipping. And, the shipping industry is required to develop and improve the energy saving ship operation technologies to meet the above IMO guideline. The weather routing is one of the energy saving navigation technologies and widely adopted by oceangoing merchant ships. The effectiveness of the weather routing mainly depends on the accuracy of weather forecast data and the ship’s propulsion performance prediction. The propulsion performance in the actual sea is usually predicted using the Self Propulsion Factors obtained by model tests. It is necessary to understand the propulsion performance characteristics in the actual sea conditions for the improvement of propulsion performance prediction. From the above points of view, the authors performed full-scale experiments using a training ship in order to investigate the propulsion performance characteristics in the actual sea. This paper describes the analysis results on the characteristics of Power Curves and Self Propulsion Factors under various weather and sea conditions.

Emergency Unberthing without Tug Assistance

Shipmasters may have to perform unberthing without tugboat assistance when a tsunami warning is issued. Keeping this in mind, the authors studied emergency unberthing without tug assistance by conducting numerical simulations and full-mission ship maneuvering simulator (SMS) experiments. A panamax class medium-sized bulker and a pure car carrier (PCC) were used as test ships. In the experiments, they established the limitations of basic shiphandling techniques such as stern kick out, backing, and accelerating turn in windy conditions using a mathematical modeling group (MMG)-type mathematical maneuvering model. On the basis of the results, they produced a shiphandling scenario and evaluated it using SMS experiments. They concluded that unberthing without tug assistance in 5 m/s onshore winds is possible. Furthermore, the use of thrusters can greatly reduce the time required for unberthing.