Mun-Sung Kim

Analysis of Full-Scale Hull Girder Loads of a Container Carrier and Its Simulation Using a Nonlinear Seakeeping Program

ABS, SHI, and OOCL have been conducting a project on full-scale measurement of hull stress of a container carrier since 2006. A Hull Stress Monitoring System (HSMS) was installed on an 8063 TEU container carrier recording hull girder loads and other navigation data. Vibratory responses of the hull girder were recorded at certain conditions, such as in the limited fetch storm waves in the Mediterranean Sea. The recorded data has been analyzed to determine the level of vibratory responses and the conditions in which they occurred. Since the vibratory response is superposed to the wave frequency component of the hull girder loads, it also affects the statistics of the maximum hull girder loads in waves. The effects of the vibratory responses in the long-term have been investigated for the dynamic Vertical Bending Moment (VBM) and bow acceleration. While the full-scale measurement provides valuable data for what actually happened in real vessel operations, the actual conditions can not be controlled, such as the wave environments or loading conditions. Hence, numerical calculation results are also desirable to investigate the vibratory responses under controlled conditions taking into account the elastic hull girder properties under exact conditions for validation purposes. ABS has been applying a time domain nonlinear wave/body interaction analysis program, NLOAD3D, for the assessment of the structural responses of vessels in large waves. The NLOAD3D program has been further developed to incorporate an elastic beam model to reproduce vibratory hull girder responses, with the simulations being carried out on motions and moments for selected notable events recorded during the voyages. Comparisons of the simulation and the measurement are presented.Copyright

Basic Research of Optimum Routing Assessment System for Safe and Efficient Voyage

This paper introduces basic research of optimum routing assessment system as voyage support purpose which can obtain safe and efficient route. In view point of safety, the prediction of ship motion should be evaluated in the condition of rough weather This part includes general seakeeping estimation based on 3 dimensional panel method and parametric roil prediction. For increasing voyage efficiency, ETA(Estimated Time of Arrival) and fuel consumption should be calculated considering speed reduction and power increase due to wave effects based on added resistance calculation and ship performance characteristics. Basically, the weather forecast is assumed to be prepared previously to operate this system. The idea of these factors in this system will be helpful to escape from dangerous voyage situation by wave conditions and to make optimum route planning based on ETA and fuel consumption.

Development and Evaluation of Optimal Routing System

To improve the safety and efficiency of trans-ocean voyage, authors developed a new onboard weather routing system (so called SORAS). The system utilizes weather forecasting data to evaluate seakeeping performance and to generate optimized route plan with respect to fuel consumption and sailing time. The system can provide decision support for navigator in real time. For this feature, onboard wave measurement system and hull stress monitoring system are integrated to provide real time wave information and actual hull stress and bow acceleration. The optimal route depends on not only weather condition but also ship’s propulsion performance. We performed a simulation study to determine the accuracy limit of mathematical model for propulsion performance. To evaluate the system, we compared calculation results with actual voyage data. The estimation results of speed reduction and fuel consumption showed good coincidence with measurement results. The wave bending moment was estimated on the forecasted wave condition. The results were compared with measured wave bending moment. For optimal route, it was confirmed that the efficiency of optimal route is superior to the efficiency of the actual route which planned by captains or officers, and the improvement of efficiency would be significant.Copyright