To better study the biology and ecology of hadal trenches for the marine scientists, the hadal science and technology center (HAST) of Shanghai Ocean University has made a significant commitment to develop operational support for the promotion of hadal science. The first focus of HAST is to construct a movable laboratory for hadal trenches which includes a mothership, an full ocean depth (FOD) Human Occupied Vehicle (HOV), an FOD Autonomous and Remotely-operated Vehicle (ARV) and several FOD landers. All of them are named as Rainbowfish series.
Presently, the construction of the ARV has been finished and the first phase sea trial has been conducted in South China Sea from September 26th to October 25th 2015. In the sea trial, the ARV was laid down to certain water depth and recovered back to water surface through a load-bearing armored cable. The reliability of the cable is critical to the safety of the ARV, as if the cable was broken, the ARV could hardly be retrieved. In such circumstances, this paper focuses on two important issues, i.e. the tensions of the cable and the ARV offset using numerical methods. Due to the change of the mothership in the final phase before the sea trial, the cable analyses with two different types of supporting vessels (a catamaran and a barge) were performed respectively and a comparison was made. In addition, a sensitivity study of submergence depths and winch hook positions was also conducted. Finally, the first phase sea trial of the ARV was described and discussed.