Sentry is a new, state-of-the-art underwater robot that can operate independently of the ship.
Sentry is an autonomous underwater vehicle (AUV), an underwater robot that swims freely beneath the surface without being tethered to a ship, capable of operating at 4500 meters below the surface of the ocean. Equipped with a sophisticated RESON sonar system (RESON SeaBat 7125), Sentry can collect the data needed to make seafloor maps at 1-cm resolution, which is incredibly detailed for such maps. The basic design of Sentry consists of a monolithic hull designed to provide static stability in pitch and roll as well have minimal drag as the vehicle moves through the water. Control foils and thrusters, located both fore and aft on the vehicle, are capable of swivelling 270º which allows the vehicle to be hydrodynamically efficient and to move up or down in the water without forward motion. Sentry is powered by 1000+ lithium-ion batteries specifically designed for high pressures. The vehicle is programmed with survey coordinates and then steers itself with a magnetic compass, long-baseline (LBL) navigation triangulated from underwater beacons, an internal guidance system (INS), and an acoustic sensor that can track the vehicles' direction and speed when Sentry is within 200 m of the seafloor. During this cruise, Sentry will be preprogrammed to “fly” over the node sites along overlapping survey lines at a constant altitude above the seafloor.