WireWalker Experiences with Two Navy-Funded Systems Utilizing Iridium Communications

The WireWalker wave-powered profiler system was designed by the Ocean Physics Group at Scripps Institution of Oceanography (SIO) University of California San Diego over 16 years ago [1]. The WireWalker system uses an ingenious ratcheting system to walk down a wire rope due to the wave action acting on a surface buoy, with a wire attached below the buoy and weights at the end of the wire for tautness. A rubber stopper attached to the wire rope at the desired depth trips the ratcheting mechanism to allow for a free-floating clean profile of data on ascent, while an upper stopper trips the mechanism to allow ratcheting down again. The Office of Naval Research and the National Science Foundation supported further development of these systems over the years. In 2016, the successful technology transition allowed for the formation of Del Mar Oceanographic, LLC to manufacture the WireWalker systems under license from the University of California San Diego. In 2017, the Navy funded the Multiscale Ocean Dynamics Group at SIO to provide two WireWalker systems with inductive modems and Iridium Router-Based Unrestricted Digital Internetworking Connectivity Solutions (RUDICS) communications for near-real-time data collection. The requirements of these two WireWalker systems were for transmission of conductivity, temperature, pressure, optical backscatter, chlorophyll a, irradiance, and radiance (along with system health) and for a Nortek Signature 1000 Acoustic Doppler Current Profiler to collect water current data and record the data internally. Within these WireWalkers, RBR Global in Canada integrated its conductivity-temperature-depth recorders with multiple channels and modem capability to transmit data inductively through the wire rope to the surface buoy. RBR Global also provided electronic integration for the surface buoy to transmit data through Iridium satellites utilizing RUDICS. Training at SIO [2] and onboard the R/V Robert Gordon Sproul in September 2017 will be discussed. Details of field experiences in February, September, and October 2018 and January-February 2019 will also be discussed. Technical problems encountered in the field and troubleshooting allowed Naval Oceanographic Office scientists to quickly learn the system and determine its deficiencies. This work helped to further debug and refine the WireWalker real-time system development and technical information required to ensure successful field operations by novice users of the WireWalker system.