Study On Wave-induced Motion Of The Large Derrick Barge Ships

As the further development of the ocean engineering, derrick barge ships become larger and larger. The derrick barge ships' B/T is greater than the general ships' B/T. Based on the derrick barge ships' character of ultra-shallow draft, this paper calculates the hydrodynamic coefficient for every degrees of freedom on the condition of the general ocean environment. Then this paper calculates the derrick barge ships' wave-induced motions of the six-degrees of freedom on the regular waves in different steepness. As the further studying, the paper calculates the derrick barge ships' responses spectrum on the condition of the irregular waves. All these studying are very important to analyze the hydrodynamic coefficient and estimate the motions of the derrick barge ship for the security.The main parts of this paper are shown as follow:The added mass coefficients and the damping coefficients of the derrick barge ships are accurate calculated. The three-dimensional derrick barge ship can be divided into 20-equal two-dimensional strips. The paper calculates every strip's added mass coefficients and damping coefficients by the Frank theory, which modified the irregular frequency by the Faltinsen theory. The proper theory obtains the reasonable result, which is in close proximity to the Kim's result.Based on Salvesen strip theory, this paper calculates the sailing ship's response amplitudes of the every degrees of freedom, which acclimatize itself to the regular waves. Under sail, the ship's response spectrums are calculated on the irregular waves in this paper.When the derrick on the ship is working, the ship's wave-induced motions on the sea are calculated in this paper. In the same time, the ship's mooring system and the lifted heavy are taken into account necessarily. All the theory and methods were created in this paper are precise and refined to the hydrodynamics of the large derrick barge ships. They fill the research blank of this domain in our country. The conclusions are very useful to research the large derrick barge ships and the designing of them.