Deep Ocean Pathfinding-High Resolution Mapping and Navigation

The introduction of deep ocean multibeam mapping systems such as Sea Beam, to the oceanographic community has resulted in a more than hundred-fold increase in survey resolution, and has provided practical potential for complete survey coverage. With deep water resolution of 100-200m, these systems have not only placed severe demands on shipboard navigation systems, but have by themselves permitted accurate terrain following navigation in areas previously surveyed. This paper describes the Sea Beam survey systems and associated navigation systems installed and operated aboard the R/V´s CONRAD and ATLANTIS II by the URI/NECOR Sea Beam Facility. The CONRAD is a well equipped geophysical research ship with multichannel and precision gravity capabilities. Its navigation equipment includes Range-Range Loran C, two-axis doppler speed log, SATNAV, and GPS with atomic clock. The ATLANTIS II is the support ship for the submersible ALVIN, and is equipped for acoustic transponder and range-bearing navigation in addition to speed log, Loran C, SATNAV, and GPS. Operations, applications, and results from survey cruises aboard these two vessels will be reviewed.