Practical Features of Ecdis Safety Depth Calculation

Abstract

The safety of marine navigation in coastal areas and narrow waters, which account for 80% of total navigational accidents, remains a pressing concern. These circumstances indicate the need to improve traditional and automated methods of passage planning and control of navigation and traffic management processes, based on the assessment of the actual navigation accuracy and navigation safety parameters. According to current industry recommendations, the main parameters of safe navigation are safety depth, safety contour, permissible cross-track limit, and accuracy of position fixing. This study deals with the development of a general practical approach to the calculation of the safety depth, as one of the main safety parameters in the ECDIS system, with an increased focus on those aspects of calculation where navigators tend to make mistakes. Analysis of data obtained during the training on the ECDIS simulator for navigators directly involved in the passage planning process (master, navigation officer) showed systematic mistakes in assessing the route safety, which can lead to ship grounding in real world. At the same time, navigators often do not recognize the danger, misinterpret it or make mistakes when checking the passage plan for safety. The results of the competence assessment showed that 40% of masters and 30% of navigation officers make mistakes in calculating the safety depth. The most common mistakes are the incorrect application of category zones of confidence (CATZOC), miscalculation of the minimum depth on the route, miscalculation of the tide height, tidal window period, the neglect of corrections for increased draught due to roll and pitch. The paper suggests that the UKC (under keel clearance) company policy shall take into account the accuracy of chart information. Furthermore, the research further develops the method of calculating the safety depth, implemented in the software, which makes it possible to systematically assess the safety of a route with multiple legs with heterogeneous parameters.