Second-Order Slowly Varying and Mean Value of Pitch Motion of the Sandglass-Type Floating Body With Dynamic Positioning System

This paper takes the presented concept of sandglass-type floating body as the research object. The shape of new sandglass-type floating body has extended oblique characteristic, which may result in special performance and the problem of pitch (or roll) motion. From the experimental tests, it can be found that its pitch natural frequency is small and the second order slowly varying pitch motion in irregular wave is significant, which may cause an unintentional interaction between the pitch and surge motions. Additionally, the floating body with small-waterplane-area and low metacentric height may have obvious mean pitch angle with wind moment under harsh sea condition. To solve the above two problems, numerical simulations have been conducted with two sea conditions. Lastly, based on the existing technique, the problems are solved and the positioning accuracy can be satisfied well for the harsher sea condition.