REDUCING SWING OF A CRANE SHIP’S SUSPENDED LOAD USING COUPLED MOTION ANALYSIS

Abstract

 In offshore construction using hoists, techniques for reducing the motion of suspended loads contribute greatly to improving the safety and operability of the work. The heave compensator is one of the methods used to reduce the motion of a suspended load, but it cannot reduce the motion of a suspended load in the direction of the surges and sway. It is desirable to use the crane’s slewing, hoisting, and lowering motions to reduce the motion of a suspended load, but the crane cannot follow the motion of the suspended load because the slewing and lowering motions of a hoist vessel are designed to be small for lifting heavy loads. Therefore, this study investigates a method to reduce the motion of a lifting load only by lifting and lowering movements, using phase differences based on the principle of parameter excitation. It was found that varying the wire rope length can reduce the motion of a suspended load significantly.