Study On Environment Loads And Static Dynamic Positioning Capacity Of Ships At Sea

Dynamic positioning technology has a wide application in work ship such as divingsupport vessel and cable layer which need the capacity of keeping precise positions for a longtime in relatively high sea state and deep water depth. Studying the methods of estimation ofenvironmental load, thruster power, plant configuration and dynamic positioning capacity inaccordance with operational requirement has important meaning to the design and research ofthe DP vessel.The direct pressure integration method is used to calculate second order wave forces ofseries ships in the thesis. On the basis of the calculation, using multiple regression analysisbased on orthogonal method, the regression equation of second order wave forces is got andproof analysis is made. The regression equation of current and wind load is also studied andcompared with the wind tunnel test.The experimental and CFD investigations of thrust deduction of side thruster in differentcurrent speeds and directions are studied. Changing rule of thrust deduction of multiplethrusters and influence of thruster spacing to thrust deduction are investigated. Finally thestatic DP capability program is presented which can evaluate the maximum weatherconditions in which a DP vessel can maintain its position and heading for a proposed thrusterconfiguration.The calculation result of static dynamic positioning capability of one salvage vessel shows that error of maximum weather conditions compared with the software provided byforeign DP control company is about10%. There is some practical value for engineering onevaluating dynamic positioning capacity during earlier stage of project design.