The U.S. Navy recently conducted a test of its UUVs (Unmanned Underwater Vehicle) in Chesapeake Bay, near Norfolk, Virginia. This test used 13 Remus 100 UUVs to test new software that enables groups of UUVs to quickly search the sea bottom for naval mines. But only nine of the 13 Remus 100 UUVs returned. Four are missing. The navy has warned local boaters to be on the lookout for the lost UUVs, as some of them may simply be floating, dead in the water. This presents a danger to boaters, especially those in small speed boats.
The Remus 100 is a 37 kg/80 pound vehicle that looks like a small torpedo. They are 1.75 meters/5.4 feet long and 190mm in diameter. Carrying a side scanning sonar, and other sensors, a Remus 100 can stay under water for 22 hours, traveling at a cruising speed of five kilometers an hour (top speed is nearly twice that.) The UUV can operate up to 100 kilometers from its operator, and dive to 100 meters/300 feet. The Remus keeps costs down by using GPS, in addition to inertial guidance. The UUV surfaces every hour or two to get a GPS fix, receive instructions and transmit data, and then goes back to doing what it was programmed to do. It's not uncommon for a Remus to get lost while doing its job, but four at once is a bit odd. The UUV has an emergency transponder, which has not worked in this case.
Remus 100 was designed mainly for civilian applications (inspecting underwater facilities, pollution monitoring, underwater survey or search). But there are similar military and police applications, like searching for mines, or other terrorist activities. The U.S. Navy uses Remus, as do many other chores. This is in addition to many tasks conceived by the many civilian users. Australia and New Zealand also use Remus 100, and over 200 are in use (about a third of all UUVs). Depending on sensors carried, each Remus costs $250,000-500,000. The U.S. used Remus 100 in Iraq, to search for naval mines.
There is also a larger version, Remus 600. This is a 240 kg (528 pound) pound vehicle that looks like a small torpedo. It is 3.25 meters (10 feet) long and 320mm in diameter. Carrying a side scanning sonar, and other sensors, a Remus 600 can stay under water for more than 24 hours, traveling at a cruising speed of 5.4 kilometers an our (top speed is nearly twice that.) The UUV can operate up to 100 kilometers from its operator, and dive to 600 meters (1900 feet).