Comprehensive Evaluation Of The Safety Of Ship Navigating In Ice-Covered Waters

Most of the excellent ports of northern China are distributed alongside the Yellow Sea and Bohai Sea. It will freeze in the two sea areas every winter, which makes the navigation of vessels in the two areas more difficult and dangerous. At present, the regulatory administrations do not adopt any guidance document to tell seafarers what kind of vessels is allowed to navigate in ice-covered waters with particular ice conditions. It just prescribe that vessels without ice strengthening are forbidden to navigate in the northern waters of Qingdao in winter. The approach of "one size fits all" is certainly able to reduce the traffic accidents in the two sea areas in winter. But it also lead to the shortage of the marine transportation in north, which will bring considerable constrains for the economic development of the northern China. It is urgent to introduce a more reliable guidance document to give vessels navigating in the two sea areas in winter some references and predict that whether it is safe if they negate in the ice-covered waters.Studies on the safety of vessels navigating in ice-covered watered are mainly divided in two areas by far. One is to simulate the collision scene of ship and ice in the glacial pool or by internet technology. According to the experimental data collected, researchers deduce the corresponding empirical formulas and the changes of the vessels and ice in the collisions, which usually provide certain references in the design of new ships. The other area is some precautions and related recommendations provided by experienced captains or seafarers who have experiences of navigating in ice-covered waters, which have a great practical referring value for seafarers who is going to navigate in ice-covered waters.After reviewing a large number of literatures, it starts from analyzing the ice conditions in Yellow Sea and Bohai Sea and the influence of ice on the navigation safety of ships, this thesis introduces the Lindqvist formula to analyze the forces (mostly the ice resistance) on the ship in ice-covered waters and the requirements of the engine power in "Classification Rules of Steel Sea-going Vessel" (CCS,2014) for vessels navigating in ice-covered waters. It is found that factors which have the greatest influence on ice resistance are engine power、speed、the ice thickness, etc.. It only takes the ship and sea ice into consideration and selects 14 evaluation indexes in this thesis. "The evaluation index system of vessel navigating in ice-covered water" is formed later and specialist marking method is also introduced to evaluate the importance of these indexes. Then fuzzy comprehensive evaluation method based on entropy is used to select the indexes with the greatest weight. It finds that the bow strength, speed, engine power and the ice thickness are with the greatest weight, which indicates that they have the greatest influence on the safety of ship navigating in ice-covered waters. At last, it takes one vessel navigating in ice-covered waters of Yellow Sea and Bohai Sea as sample to calculate the maximum ice thickness broken by the vessel in different speed with Ranicki formula. It also conducts the Comprehensive Evaluation on the safety of the selected ship in the ice-covered water of Liaodong Bay.