A Review of the Bathymetric Swath Survey System

The appearance in recent years of large ships with drafts approaching 30 metres has a serious impact on U.S. charting requirements. Previously, detailed harbor approach surveys were accomplished sufficient to define hazards within the 20-metre contour. The new, larger, commercial ships now require surveys to assure that all hazards and obstructions within 30 metres of the surface are located in charted channels, harbor approaches and ship fairways. A multi-beam bathymetric swath survey system (BS1) described here has the potential to meet these new survey needs. The BS’ employs a vertical fan-shaped array of 21 acoustic beams which forms a swath beneath the survey vessel with a width equal to 2.6 times the sounded depth. In addition to the usual vertical acoustic sounding, the oblique acoustic soundings are recorded and processed in real time to display contours of bottom features shoaler than the vertical depth. A computer is part of the B S \ utilizing a real time operating system to merge soundings, navigation inputs, real time telemetered tides and ship motions to output corrected soundings graphically and to a magnetic data tape. System development began in July 1976 and was delivered in September 1977. Preliminary field tests on a Government launch and aboard the NOAA survey ship Davidson are now being evaluated and the data analyzed. Indications are that the system will soon be certified and delivered to the NOAA survey fleet as an operational marine chart survey system