ORCA´s oceanographic sensor suite

The Mapping, Charting and Geodesy Branch of the Naval Research Laboratory (NRL) at Stennis Space Center, MS, is conducting a multi-year program for the development of unmanned, untethered sensor systems for the collection of tactical oceanographic data in littoral regions. This paper reviews the sensor systems, program progress to date and the future plans for a comprehensive oceanographic survey system. The prototype platform currently in use for this project is the ORCA semi-submersible. The ORCA is an air-breathing vessel which travels just below the water surface. The vessel utilizes a direct radio link for real-time data and control communications, as well as a DGPS system for precise platform positioning. The primary sensor installed on ORCA is the Simrad EM950 system which collects bathymetry and collocated acoustic imagery in water up to 300 meters in depth. With realtime data telemetry to the ORCA host vessel and the NRL developed HMPS bathymetry post-processing software, the system is capable of same-day chart production. In contrast to a full size survey vessel, ORCA is able to collect bathymetric data of the same quantity and quality, but will have one fortieth the life-cycle costs. Other sensors being integrated into ORCA include an acoustic sediment classification system, an acoustic Doppler current profiler, and obstacle avoidance systems