A Hydroid marine robot surveys wreckage from D-Day training exercise that went badly

The Remus 100 is readied for an Exercise Tiger mission. Photo courtesy of Hydroid.

Hydroid Inc., a Bourne company that manufactures autonomous underwater vehicles, or AUVs, said Tuesday that one of its marine robots recently surveyed the debris fields of two US Landing Ship Tanks, or LSTs, that were sunk about 30 miles off the southern coast of England by German torpedo boats during World War II.

A side-sonar scan image of a sunken LST. Image courtesy of Hydroid.

The AUV mission, undertaken in early March in concert with a unit of the British Royal Navy, was part of an effort to mark the 70th anniversary of Exercise Tiger, an April 1944 training exercise for the invasion of Normandy’s Utah Beach a short time later. Nearly a thousand US military personnel were killed during Exercise Tiger, more than the number of deaths at the actual invasion of Utah Beach, Hydroid said; it was the most deadly training mission involving US service men during World War II.

A Hydroid AUV called the Remus 100 was deployed to collect data from the wreckage sites of LST 507 and LST 531 by using high-definition sonar images. This was the first time an AUV had surveyed the area, Hydroid said. Hydroid and the Royal Navy plan to donate these images to the UK National Archive and local memorials.


The Remus 100 was equipped with multiple sonar instruments that enabled it to capture high-resolution imagery of objects on the sea floor. The data showed that both the sunken LSTs are about 50 meters below the surface.

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“The Remus 100 also discovered an object of interest close to the shore which may hold significance in relation to Exercise Tiger,” Hydroid said in a press release.

“Steps to identify this object are currently being taken,” the company added.

At first glance, the Remus 100 seems to resemble a 90- to 100-pound torpedo. It is about six feet long and eight inches in diameter. It often performs four-hour long missions at a cruising speed of about four knots. The 100 in the REMUS 100 name signifies that it can operate at depths of up to 100 meters.

Designed to operate in “coastal environments,” the REMUS 100 is suitable for marine research and for customers in the offshore energy markets as well. The REMUS 100 is the only compact AUV to be selected by the US Navy for mine counter-measure operations, Hydroid says.


In 2011, a trio of Remus 6000 AUVs, under the direction of the AUV Operations Group from Woods Hole Oceanographic Institution,  were used to find the wreckage of Air France Flight 447, which crashed in the Atlantic Ocean in 2009. As the name suggests, the Remus 6000 can operate at depths of up to 6,000 meters.

Hydroid Inc. is a subsidiary of Kongsberg Maritime of Norway.

Chris Reidy can be reached at