Magnetic sledge introduced for retrieving objects from seabed

June 29, 2016

Magnetic sledge introduced for retrieving objects from seabed

Miko Marine has introduced a magnetic sledge for finding and retrieving ferro-magnetic objects from the seabed. Responding to an urgent request from the Accident Investigation Board of Norway, Miko engineers were able to design, build and deliver the sledge within four days.

Oslo-based Miko Marine has introduced a magnetic sledge that is capable of retrieving ferrous objects small as a fingernail from underwater. Measuring two by one metres, the sledge is made from aluminium and equipped with 10 powerful permanent magnets. When towed over the seabed the sledge can pick up objects that may be covered by sand or silt and achieve results that would be difficult or impossible for divers to equal.

Magnetic sledge 3D model

Each magnet is suspended independently beneath the sledge from a flexible mount that enables it to pass over rough or broken ground without damage or becoming snagged. Capable of working at any depth, the sledge can be equipped with a video camera and an acoustic positioning system such as a Sonardyne Scout linked to a GPS chart plotter. This enables it to follow an accurate search pattern and ensure that nowhere is missed. The sledge is typically fitted with buoyancy to offset the weight of the magnets so it can be handled efficiently and for the height at which it is towed above the seabed to be precisely controlled.

The Miko magnetic sledge is a potentially useful tool for police and accident investigations. One was recently used to successfully recover parts from a Super Puma helicopter that tragically crashed into the sea near Bergen, Norway in April. The aircraft went down with the loss of two crew and eleven passengers during a flight from the Statoil Gulfaks-B platform. It went into relatively shallow water close to the shore near Turoey and subsequently caused the world’s fleet of Super Puma helicopters to be grounded until the cause of the accident is known.

Delivered in four days

Although much of the wreckage was quickly recovered, accident investigators were anxious to study the helicopter’s transmission. The Accident Investigation Board of Norway consequently commissioned Miko Marine to design and build a sledge that could be used to recover ferro-magnetic debris hidden beneath the seabed around the crash site.

Magnetic Sledge in use underwater

Miko Marine is a salvage technology company based in Norway that has particular expertise in the use of magnets. Responding to the urgency of the request, Miko engineers were able to design, build and deliver the sledge within four days.

The sledge was operated from a 12-metre workboat catamaran that surveyed an area of seabed measuring some 400 by 700 metres, working 12-hour shifts over a period of two weeks ending on the 20th May. By the end of the search a number of metal objects had been recovered for analysis including the vital components from the helicopter’s transmission system.

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