Location and recovery of lost instruments using acoustic targets

Despite the increasingly reliable techniques and technologies developed by the oceanographic community, the all too frequent failures of instruments and moorings to surface on command remains a problem. The loss of both equipment and data is costly to the community. In our experience, the effort to locate and recover lost equipment, even in shallow water, has often been futile and costly. In this paper we describe a low-tech, approach that we have developed and used to recover two lost instruments. Our approach utilizes passive acoustic targets, side scan sonar, and divers. A large research vessel is not required, the targets can be readily manufactured from stock material, and, in deeper waters, ROVs can replace the divers