SLOCUM: an underwater glider propelled by environmental energy

SLOCUM is a small gliding AUV of 40 000-km operational range which harvests its propulsive energy from the heat flow between the vehicle engine and the thermal gradient of the temperate and tropical ocean. The design of both the glider and the thermal engine are discussed including the design genesis and approach, field trial results, concept strength, and limitations and potential use.

I. Background

In 1978, a group at the Woods Hole Oceanographic Institution (WHOI) discussed adding horizontal propulsion to SOFAR floats [1]. These discussions created the nucleus of thinking that led to the SLOCUM design. Looking back, there are two interesting features of these discussions: they specifically addressed understanding circulation rather than hydrography; that is, a moving vehicle might provide more insight than a fixed mooring or a drifting, neutrally buoyant float; and many important system components were in place, a large neutrally buoyant vehicle with a substantial battery and an appropriate acoustic navigation and telemetry system.