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Efficiency of a voluntary speed reduction algorithm for a ship’s great circle sailing

Wang H., Mao W., Eriksson L.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2020

Vol. 14, no. 2

301--308

The great-circle is the shortest distance between two points on the surface of the earth. When planning a ship’s sailing route (waypoints and forward speeds) for a specific voyage, the great circle route is commonly considered as a reference route, especially for ocean-crossing seaborne transport. During the planning process, the upcoming sea weather condition is one of the most important factors affecting the ship’s route optimization/planning results. To avoid encountering harsh conditions, conventional routing optimization algorithms, such as Isochrone method and Dynamic Programming method, have been developed/implemented to schedule a ship’s optimal routes by selecting waypoints around the great circle reference route based on the ship’s operational performances at sea. Due to large uncertainties in sea weather forecast that used as inputs of these optimization algorithms, the optimized routes may have worse performances than the traditional great circle sailing. In addition, some shipping companies are still sailing in or making charting contracts based on the great circle routes. Therefore, in this study, a new optimization algorithm is proposed to consider the voluntary speed reduction with optimal speed configuration along the great circle course. The efficiency of this method is investigated by comparing these two methods for optimal route planning with respect to ETA and minimum fuel consumption. A container ship sailing in the North Atlantic with full-scale performance measurements are employed as the case study vessels for the comparison.

Development of Solution for Safe Ship Considering Seakeeping PERformance

Yoon H.K., Nguyen V.M., Nguyen T.T.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2018

Vol. 12, no. 3

517--525

In recent years, safety of a ships has become one important issues needed to solved as soon as possible in ship navigation. Optimal weather routing is one of best solution for ensuring safe operation of a ship with a with short passage time or minimum energy to avoid a certain excessive motion. This paper introduced the development of solution for safety and optimal weather routing a ship considering seakeeping performance based on model test result. This study introduced how to apply A* algorithm based on result of the seakeeping model test for determining the optimal ship routes. Seakeeping model test of 8600 TEU container ship was carried out in Changwon National University's seakeeping basin and its RAOs at various frequencies were used to predict the RMS motion values in irregular waves. The specially modelled path-cost function and the safety constraints were proposed for finding the optimal path of the ship. The comparison of ship performances estimated by great circle’s path and estimated optimal route during the voyage of the ship was investigated.