Efficiency of a Voluntary Speed Reduction Algorithm for a Ship’s Great Circle Sailing

• Published in: TransNav, the International Journal on Marine Navigation and Safety of Sea Transportation
• Main Authors: Helong Wang, Wengang Mao, Leif Eriksson
• Format: Article in Journal/Newspaper
• Language: English
• Published: Gdynia Maritime University 2020
• Subjects: great circle sailing; algorithm; ship’s sailing route; route planning; dynamic programming (dp); great circle route; great circle (orthodrome); estimated time of arrival (eta); Canals and inland navigation. Waterways; TC601-791; Transportation and communications; HE1-9990; Eta; North Atlantic
• Online Access: https://doi.org/10.12716/1001.14.02.04; https://doaj.org/article/61c8b5ac1c434c20a4abd97ffc235790

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.