Evaluation of a deep water wide swath echo sounder for hydrographic surveys

Discusses the evaluation of multibeam echo sounders according to the hydrographic survey standards. The French Hydrographic and Oceanographic Service (SHOM) operates two multibeam echo sounders. Both have been accepted as hydrographic (meaning that they meet the hydrographic accuracy standards) for a determined swath width. The first system, a Thomson SINTRA shallow water 20 beams echo sounder called LEMYERMOR, was acquired in 1988. The second system, a SIMRAD EM 12 dual 160 beams deep water echo sounder, was installed and put into service in 1993. Using SHOM experience, this paper mainly describes some “bias” that were observed when evaluating the accuracies of both echo sounders but is mainly based on the sea trials of the EM 12, that were held in 1993