There are two types of underwater vehicles being used for the Ocean Observatories Initiative (OOI) – Autonomous Underwater Vehicles (AUVs) and gliders.
AUVs are small propeller-driven vehicles. Because they go quite fast and are rather small, they typically last one or two days on a battery charge. In the OOI program they will be used in the coastal arrays for surveying an area of 100 x 80 kilometers (62 x 50 miles) and from the ocean surface to 600 meters (1,969 feet) deep. On each battery charge they typically cover a distance of 250 kilometers (156 miles). After an extensive survey the AUVs will need to return to a mooring with a “docking station,” where the batteries will be recharged for the next trip. After roughly 120 days of work at sea, the AUVs will be recovered for maintenance on shore.
Gliders will be used in both the coastal and the global OOI arrays. They have no propeller and move like a glider plane with wings. These underwater gliders have an oil bladder that is pumped up and released to make them go up and down. The coastal glider can cover about 1,800 kilometers (1,118 miles) on a single battery load, which can last about three months. For the global gliders, Scripps Institution of Oceanography at UC San Diego researchers are hoping to achieve an endurance of one year, with a range of 8,000 kilometers (4,971 miles). This amazing efficiency is obtained from the gliders by going much more slowly and using extremely low-power electronics and sensors.
-- Uwe Send, professor of physical oceanography, Climate, Atmospheric Sciences, Physical Oceanography Division