Seakeeping Analysis Of The Large Self-propelling Cutter-suction Dredger

The large self-propelling cutter-suction dredger is an engineering ship which is entirely ableto navigate in ocean and it's ship form has marked difference with the ordinary ships because ofthe request of construction arrangement. For example, there are large slot cuts both in the bow andstem to set up cutter frame and steel pile trolley. The slot cuts in the bow and stem will have anaffect on ship's seakeeping, and how well of the seakeeping concerns the ship's habitability, safetyand economical efficiency, so it has a significant meaning to study the seakeeping of the largeself-propelling cutter-suction dredger. There usually are two forms of slot cut in the bow and sternof the self-propelling cutter-suction dredger according to the setting position of the cutter frameand steel pile trolley, it also has a significant meaning to study which cut form has a betterseakeeping.In this paper we choose three self-propelling cutter-suction dredgers as the calculate model,ship model I with the cutter frame arranged in bow, ship model II without slot cuts in bow andstem and ship model III with the cutter frame arranged in stern. Comparing the calculation resultof seakeeping performance to the three model, we will find the influence of the seakeeping causedby the slot cuts in bow and stern and which slot cut form has a better seakeeping performance.This text only research the sailing seakeeping of the large self-propelling cutter-suctiondredger, exclusive of dredging state. First, according to 2nd law of Newton this dissertationdiscusses the motion performance of ship navigating in waves and sets up a series of linearequations of ships response in regular waves in case of linearity based on the three dimensionalpotential theory. Solving the equations obtains the six degree of free amplitude response functionof ship motions in seaway. Utilize the theory of linear system of stationary stochastic processesand choose appropriate wave spectra, obtain various seakeeping factors'motion response spectraldensity function in stochastic waves of ship, then utilizing the knowledge of statistics obtain thechanging curves of various seakeeping factors'significant amplitude with the changing course andspeed, from above we can discover the connection between navigational mode and various ship's motion performance. Then apply the wave data of ocean environment, according to the relatedtheories, to calculate and analyze the long-term prediction of ship's seakeeping, moreover obtainssome significant conclusions. Finally, the research introduces a computational method ofcomprehensive evaluation index (the percentage of the task time of ships) which can reflect theentire performance of seakeeping of ships, then apply the method to calculate and analyze thepercentage of the task time of ships based on the wave data of ocean environment, and alsoobtains some significant conclusions.The calculation results show that the slot cuts both in the bow and stern will reduceseakeeping performance of a ship, and a ship with the slot cuts like ship model III has betterseakeeping performance.