The Development of New & Existing Cabling Techniques to Obtain Realtime Full Water Column Current Measurements.

This paper provides details of the development of new and existing techniques for real-time transmission of ADCP data via strain bearing data cables in water depths exceeding 6,000 ft. The process of deploying several ADCPs different locations in the water column to obtain a full profile of the currents through the whole water column is a simple concept, however, reliable transmission of the data via a hardwired link with complete redundancy requires complex design to satisfy actual requirements. The requirements of the system include location of two ADCPs to avoid not just physical interference but also acoustic interference, one on the seabed and one at 500 m above seabed with 100% data and power redundancy using an existing 5,000 m of communications infrastructure and a limited number of copper lines. Furthermore, the requirements for a realtime link between the seabed frame and a buoy mounted ADCP utilizing a 500 m strain bearing armored data cable and the challenges of the associated weight and buoyancy requirements are discussed. Both systems provide realtime data to the offshore platform and are deployed and retrieved via ROV, as such both systems have underwater wet-mateable electrical and fiber optic connections. The challenges created by these requirements and constraints and solutions developed are presented in this paper. Many of the techniques applied in this application would be equally applicable to larger scale cabled observing systems