A resident subsea docking system with a real-time communication buoy moored by an electro-optical-mechanical cable

Subsea docking systems (SDSs) have received extensive attention in the past decades as the basis for achieving AUVs' long-term observations and operations. However, the existing research mainly focuses on developing custom-designed SDSs to match specific outlines and structures of AUVs, while the approach to achieving the long-term underwater residency of SDSs is less involved. Therefore, we propose a resident subsea docking system (RSDS), where an electro-optical-mechanical (EOM) cable mooring a real-time communication (RTC) buoy to a subsea docking station (SDS). Moreover, we adopt a numerical method based on ANSYS-AQWA to investigate the effects of types and design parameters of the mooring structure on its stability and reliability. The results show that the most suitable type of mooring structure significantly reduces the maximum buoy's pitch, cable tension, and anchor-uplifting force by 3.08%, 14.16%, and 55.59% compared with the traditional one. Moreover, its optimal design is a 320 m cable attaching a 200 N-buoyance float and a 1200 N-gravity clump weight at 25 m and 50 m near the SDS. Finally, the field test in the South China Sea verified the RSDS's functions and the feasibility of the optimal mooring structure. In summary, this article fills a gap in achieving the SDS underwater residency and guides future research on RSDS. •A solution to achieve the long-time underwater residency of the resident subsea docking system is proposed.•A numerical simulation based on AWQA is applied to simulate the mooring structure of the resident subsea docking system.•The most suitable type of mooring structure is obtained by analyzing the effects of the three proposed types.•The optimal combination of design parameters is obtained by analyzing the effects of different design parameters.•The feasibility of the optimal design of the mooring structure is verified in a field test in the South China Sea.