STUDY of the RELIABILITY of the SHIP TRANSPORTATION by APPLYING the HISTORICAL HINDCAST WEATHER DATA

摘要

Regularity of ship transportation depends strongly on environmental conditions, on the ship's route and on the seakeeping characteristics of a vessel. The ship's route property selected and the ship characteristics designed appropriately to a region of the ship operation can assure a higher regularity of the transportation. In the presented paper an exemplifying analysis of the ship transportation on a selected typical ship's route has been performed. The principal purpose of such an analysis was to determine the magnitude and distribution of speed losses in a realistic operational environment to serve as a basis for estimation of reliability of the sea transportation. The aim of the analysis precludes the use of long term statistics as this would not give a correct representation of the extreme value tail of the probability distribution of sailing time. Instead of this, the ship performances on the considered sea routes were simulated in roundabout trips by applying time series of historical (hindcast) weather data (waves, swell, wind, and ocean current). The applied data cover three complete years starting from February 2003 and they are specified with the 6 hour time interval at about 3000 grid points covering almost the whole world ocean area. Two vessels which represent typical classes of ships (a tanker and a container ship) were used in this analysis. The ships voyages were simulated with different departure time and with the time interval of 6 hours providing high sailing frequency and the considerable large amount of results. Results of the calculations were analyzed with respect to the seasonal variations, alternative routes, and different power settings. The purpose of these numerical exercises was to illustrate how to perform the analysis and to present a scope of the obtained results.