Acoustic issues from a marine surveyor's viewpoint

Abstract

The ships and instrumentation used in the National Ocean Service hydrographic and bathymetric surveying represent capital investment of several hundred million dollars and recurring annual costs of tens of millions. The efficiency in survey coverage, while maintaining required survey accuracy, is of utmost concern. Deficiencies in any of the several types of acoustic systems used in the surveys can and do contribute significantly to the loss of survey production. This paper describes briefly three types of survey missions, highlighting the acoustic systems used and the known or preceived acoustic phenomenological factors that contribute to lost production. These systems include dual frequency echosounders, multibeam swath sonar systems, and conventional side scan. The paper also discusses emerging technology, now under consideration, including both interferometric and multibeam side scan systems, again with emphasis on the critical acoustic phenomena. Finally, a new concept dubbed “the acoustic knife,” for which an experimental project is now contemplated, is discussed.