Vessels designed for navigation in ice can perform voyage with the assistance of icebreaker in the navigation season in case an ice cover area is less than 20%. Whereas the same vessels could carry out successfully completed voyage through the NSR with intensive icebreaker help at the ice-covered area lower than 42%. Navigation of the same vessel at ice covered area above 80% is possible with intensive icebreaker help, but it threatens to damage the hull, rudder or propeller. Excessive generalization of data analyzed may cause to wrong, even opposite conclusions. Using only basic statistical information in the form of average values and standard deviation may be not sufficient for the purpose of vessel’s voyage planning in areas covered with ice. Much more opportunities for the assessment of navigation in ice covered regions provides cumulative distribution, which should be related to the time and geographical space distribution. It allows to determine the duration of time window for given area covered with ice in a particular region and predetermined probability of its occurrence. It is thus possible to plan approximate date of departure and duration of voyage for assumed safety criteria. Also, it is possible to plan a number of consecutive voyages in a navigation season. Mathematical approach to voyage planning in ice based on a cumulative distribution is presented in the paper. It allows creation of an advisory computer application to support decision-making by the commander of a vessel. It will reduce the human factor in data processing and reduce possibility of making a mistake. By this way, can be enhanced the safety of maritime transport. Novell approach is verified on the example of historical data about the German Navy ship activity during the Second World War.
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