Underwater connectors are very essential and complex components of deep-sea engineering equipment and their design and manufacture have apparent multidisciplinary characteristics. Wet-mateable connectors (WMCs) represent the highest level of technology in this field, and only a very few countries in the world can produce WMCs. So, WMCs are likely to be a constraining factor to some maritime powers that might try to achieve breakthroughs in this field, constraining the innovation-driven development of deep-sea equipment. This paper gives a detailed overview of underwater connectors, both electrical and optical. First, the background of underwater connectors is introduced, and then the main available commercial off-the-shelf (COTS) products are described. Next, the new concept of functional units is proposed by the authors to help readers to have a better understanding of underwater connectors. Then, the basic theories of design are introduced according to different functional units, covering the aspects of electrical/optical connection, pressure-balanced oil-filled (PBOF) technology, penetrable self-sealing, aligning and locking structures. Finally, some discussions and conclusions are presented. This paper aims to reveal the secrets of key technologies used in underwater connectors, especially in WMCs.
An Overview of Underwater Connectors