Hirotada Hashimoto

Analysis of Satellite AIS Data to Derive Weather Judging Criteria for Voyage Route Selection

The operational limitations are discussed at the IMO as a part of the second generation intact stability criteria. Since it is a first attempt to introduce operational efforts into safety regulations, comprehensive discussions are necessary to realize practically acceptable ones. Therefore this study investigates actual navigation routes of container ships and pure car carriers in the trans‐North Pacific Ocean in winter, because they are prone to suffer significant parametric roll which is one of stability failure modes. Firstly, interviews are made to shipmasters who have experiences to have operated the subject ships to identify major elements for route selection in the North Pacific Ocean. Secondly, sufficient number of actual navigation records is collected from Satellite AIS data to derive the weather criteria for the route selection in severe weather condition. Finally, shipmaster’s on‐board decision‐making criteria are discussed by analysing the ship tracking data and weather data. http://www.transnav.eu the International Journal on Marine Navigation and Safety of Sea Transportation Volume 11

Mathematical Modeling for Ship Evacuation from Tsunami Attack

When a tsunami warning is officially announced, as a measure for safeguarding ships from tsunami attacks, it is recommended that large ships in harbors be maneuvered to sheltered areas outside the ports until the tsunami subsides. In this paper, we develop mathematical simulation models to describe the dynamic behavior of a ship. Then, the evacuation maneuvers of a cruise ship and a cargo ship in a tsunami flow are analyzed and characterized. Finally, it is concluded that this kind of simulation could be very great help useful to evaluate the safety of ship evacuation methods against for the tsunami attacks.

Advanced optimized weather routing for an ocean-going vessel

Based on current growth patterns in the global economy, there are projections that there will be an overall increase in the emissions of harmful gases from ships. The International Maritime Organization (IMO) requires the preparation of management plans to improve the efficiency of ship navigation. Moreover, shipping companies should pay careful attention to fuel consumption and environmental conservation. In this paper, we propose a newly developed weather-routing optimization technology that focuses on fuel-consumption minimization and energy-efficiency operational indicator (EEOI) minimization while on voyages. We consider the constant variations in the sea and weather conditions, including wind, wave, and current conditions. This is achieved by performing a cost-function minimization. The cost function is calculated by performing an entire maneuvering simulation from a transoceanic voyages starting point to its end point by solving horizontal differential equations of motion such as those related to the yaw, sway, and surge. The simulations consider the ships hull force, propeller thrust, rudder force, wave force, and wind force. Both sets of results obtained in this study for the optimal routes are reasonable because the values of EEOI and FOC are reduced compared with the values for the great circle route, which is the shortest path between the two points. On the other hand, the optimized route in the EEOI minimization calculation does not provide the FOC minimum value.