Optimization of ship routes is an important consideration in maritime industry. By application of optimal control theory in conjunction with hydrodynamics and weather forecasting tools, most economical and safe route can be charted. Although a large volume of work is available addressing the ship-weather-routing problem. But most of them appear to concentrate on theoretical development related to the algorithm rather than the algorithm itself. The possible reason for limited detail on the actual algorithm that is used by ship navigators may be the commercial and proprietary nature of such algorithm. Also these works do not provide any optimized sea-routes but only solutions to the idealized problems. This work focuses on development of a practical ship routing algorithm which can be used by ship navigators using on-board computers during a voyage, and routing decisions can be made as the voyage progresses. I hope the detailed and practical oriented nature of this book will be helpful for readers to gain better insight in marine navigation.