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Ocean gliders are autonomous underwater vehicles used to collect oceanographic data to better understand the ocean. The US navy uses them to plan its underwater activities.

Recently, a Slocum G2 US Navy glider was reportedly seized and returned by China in the waters of the Western Pacific. The US has approximately 130 of these gliders and they are relatively inexpensive, according to Rear Adm. Tim Gallaudet, Oceanographer of the Navy and commander, Naval Meteorology and Oceanography Command, in his blog on navylive.dodlive.mil. “The U.S. Navy will not only continue to use these technologies to improve our knowledge of the oceans, but we will be significantly increasing our use of gliders over the coming years so that our understanding of the ocean is the best in the world,” he writes.

“These underwater robots allow us to explore more of the ocean, and faster, at a fraction of the cost of a manned submersible or a ship. The information gathered allows us to better predict ocean currents, density, sea states and tides which the U.S. Navy needs to safely and effectively operate all around the world. Once deployed, a glider can persistently sample the ocean for months freeing the ship to perform other functions.”

Modular in design and buoyancy-driven the gliders can collect oceanographic data for up to four months without the need for active propulsion. The drones are made by Teledyne Webb and are sold commercially, Gallaudet points out.

According to defensesystems.com, from the underwater drone concept’s inception, a priority was given to developing a small, rechargeable and efficient li-on battery as well as the necessary algorithms and display tools to aid in glider deployment and routing for visualization and adaptive sampling. They also need to find low-frequency sound sources for navigation and tomography – a method to display a cross section through a solid object using X-rays or ultrasound.

A Teledyne underwater drone is a nearly 5-foot-long torpedo with wings. It is equipped with a sensor suite. It is driven by buoyancy change, and has no propeller, according to the manufacturer’s website.