Applying an Uncrewed Surface Vehicle to Measure Under-Pier Bathymetry

This paper describes a simple and cost-effective solution developed to map generalized bathymetry underneath Navy piers. This challenging environment is constrained by tides, ship movements, varying pier architectures, and sporadic or non-existent GPS signals. We used a small, remotely operated surface vessel with an integrated single-beam sonar system (for depth, z measurements) and geographic positioning system (GPS; for some latitude/longitude, x,y positions) and also used an ultra short baseline (USBL) acoustic positioning system to determine x,y positions when GPS was denied under the pier. This manuscript presents the methods developed, including the approach used to combine these different data streams, to allow other researchers to collect and process similar datasets in constrained environments.