Hydrographic surveying and, more to the point Bathymetry is something that is widely used and required in the land surveying and mining industries – not to mention many others. These options for determining the underwater surface or structure, and sub surface, have been in place for many years and certainly are used on vastly differing scales. These options have improved over time and continue to improve.
GeoCue Australia involves itself primarily with RC Boat based operations, this is primarily for single beam bathymetry (dual frequency), but also Side scan and Multi beam to some extent. RC platforms become relevant in any situation where a manned boat cannot be used for reasons of practicality or other rule and law, based restrictions - often these are to do with safety.
These days, RC Bathymetry boats are able to perform very much like any other modern drone (UAV/ UAS, RPAS, etc). This includes mission planning and auto pilot, drone GNSS and GNSS base stations or CORS options, PPK post processing, ‘first person view’ via live video, live indications of boat position and performance, multiple redundant systems and various other safety factors built in to protect the vessel and data being collected.
Depending on your sub surface requirements, the most ideal method can vary considerably in cost and complexity. Bathymetric systems are relatively simple to use with outputs being in an x/y/z format. Side scan sonar systems go up in cost and complexity but provide detail below the water akin to laser scanned data. Live data in a video like format is also an exciting option and aspect of some Side scan systems. Multibeam systems increase again, over Side Scan, in terms of cost and complexity but again deliver increased accuracy and precision in terms of outputs. Often the IMU unit utilized in these systems is quite important and assists in maintaining heading accuracy, particularly for any instances of GNSS outages and long run lines.
Unlike airborne based drones, RC boats have various water-based aspects and challenges to deal with. Keeping water out is an obvious and important requirement for both short- and long-term longevity of equipment.
Avoiding this challenge of course, ideally, are such options as Bathy lidar and cable-based Bathy drone operations. Flying your drone with a single beam sonar on a cable is a good option in some instances and of course Bathy LIDAR systems for drone-based use is an expensive but highly useful tool that is often indispensable.