U.S. Navy personnel today launched an unmanned underwater vehicle into Honolulu Harbor as part of a simulated exercise to search for mines.

The 67-inch, 90-pound vehicle known as REMUS — Remote Environmental Monitoring UnitS — is part of a technological effort to physically remove man from the minefield.

"In the future, we're hoping … to deploy systems like this, and probably systems a little bit larger than this for deeper waters. And that will allow us to not have to bring man systems with people on board to a minefield area," said Navy Capt. Jim Berdeguez, director of oceanography operations.

Navy officials said in addition to checking the vehicle's imaging sonar gear, which takes pictures of the ocean floor, the exercise served as a test of communications lines between the Navy and the harbor's port captain.

A team of nine sailors led by Navy Lt. Cmdr. James Coleman operated the $500,000 vehicle, manufactured by Massachusetts-based Hydroid, Inc. Using a laptop computer connected to the vehicle, team members program REMUS for a mission. They will spend about an hour programming for a six-hour mission.

Before launching REMUS from a pier, Coleman outlined its mission route. "It proceeds out toward its way-point objective, dives down and you don't see it again on the surface until you're picking it back up to get it back out for another mission," he said.

The vehicle can be launched a number of ways, such as throwing it into the water and programming it to start its mission at a depth of one meter. The model used today can dive to depths up to 300 feet and travel at a maximum speed of five knots, but the Navy limits the use to 200 feet and three knots for operational purposes.

"The sonar has two modes on it," Coleman said. "It has a standard resolution mode that searches a larger area, and a high-resolution mode that searches a very short area."

While REMUS is on a mission, the military team knows its location, but cannot retrieve any data until after it is picked up at the surface. In Honolulu Harbor, the team must navigate around ships, such as the Superferry and tankers that have large drafts, and make sure REMUS isn't hit by one. Computer control of REMUS is limited after launch, but the team can direct it to hide, wait and later resume its mission.

REMUS is durable but contains sensitive electronics in a small space, said Coleman, noting that there was a case of a model being destroyed after it was sucked into a ship's propeller.

If the unmanned vehicle spots potentially hazardous mines or other explosives, data can be uploaded from it and compared to previous surveys, and the vehicle may be directed to again search an area using its high-resolution mode. A mine countermeasure commander may also decide if a diver is required.

The Naval Oceanographic Office has operated larger unmanned underwater survey vehicles for the last 10 to 15 years. The Navy has been testing vehicles for mine detection for about two years and expects to continue for another five years before it comes more widely used, officials said.

REMUS comes in two larger versions, one of which can dive almost 20,000 feet. Other similar vehicles are used in several countries, including the United Kingdom, Australia and Germany.

Reach Kelli Miura at 535-2467 or kmmiura@honoluluadvertiser.com.