German marine salvage specialist, Eggers Kampfmittelbergung has completed its first project using underwater acoustic tracking technology supplied by Sonardyne International.

A specialist clearance diver equipped with a Sonardyne WSM 6

A specialist clearance diver equipped with a Sonardyne WSM 6

It took place during an operation to dispose of unexploded ordinance which were lying off the German coast in the Baltic Sea.

The Mini-Ranger 2 Ultra-Short BaseLine system was used to track divers as they surveyed the seabed, it recorded the location of potential targets before clearing the area of metal objects and old ammunition.

Jan Wommelsdorff, managing director at Scholz Ing.-Buero GmbH, Sonardyne's German agent, said: "Egger's decision to invest in Mini-Ranger 2 was made only after a detailed comparison of its capabilities against competing USBL technologies.”

He added: “Now after using it for the first time, it's clear that the system will indeed increase the speed and efficiency of Egger's underwater operations in North Sea and Baltic Sea as well as inshore. With the Baltic mission complete, Mini-Ranger 2 is ready for its next assignment which is likely to involve tracking a towfish as well as more divers."

The Mini-Ranger 2 has features suiting for work on nearshore operations on small quiet vessels that need survey-grade positioning.

It can simultaneously track 10 targets at fast update rates, it is quick to install and has an operating range of 995m, which is extendable to 4,000m.

Eggers deployed their Ultra-Short BaseLine system from a survey barge moored 500m off the coast. Specialist clearance divers were each equipped with a Sonardyne WSM 6 transponder attached to their back and a HPT 3000 acoustic transceiver was deployed on a pole.

During each dive, supervisors in the control cabin on the barge used Mini-Ranger 2's software display to guide divers around the site.

The system's communication link enabled each diver's distance, bearing and depth relative to the barge to be updated up to three times per second.

By Alice Mason