On Wednesday 01 May 2013, HMAS Newcastle entered the Magnetic Treatment Facility at Fleet Base West in order to undertake deperming.
The Magnetic Treatment Facility provides the capability to reduce, alter and stabilise the permanent magnetism in steel hulled vessels – limiting the issue of magentic variation in readings from the ship’s navigation systems.
Since the advent of the magnetic influence mine in World War II, steel hulled ships and submarines have been vulnerable to disablement and destruction due to the triggering of mines by the vesselís magnetic field. Normally, these fields are reduced by the onboard degaussing system, however when the magnitude of the vessels field is too large for the onboard system to compensate, the vessel must undergo magnetic treatment.
Significant magnetic effects may arise in any object containing ferro-magnetic material. The strength of the magnetic field is determined by the shape and composition of the object, and the ambient magnetic field. For a ship or submarine, the field is complex and changes with heading and location. The measured field is three dimensional in nature and is expressed in terms of three mutually independent orthogonal components; being the longitudinal, athwartships and vertical fields. The total field is the vector sum of these components. Magnetic signature minimisation can be achieved by Magnetic Treatment (or Deperming) and Degaussing.
Magnetic treatment involves wrapping large cables around the hull, forming a solenoid, to induce a controlled longitudinal field into the vessel. The vessel is then berthed in the Magnetic Treatment facility which also has a built in coil to generate a vertical magnetic field. By controlling the current (and hence the magnetic field) in both of these coils, significant reduction in the permanent magnetisation can be achieved.
The Magnetic Treatment Facility located at HMAS Stirling, is the only facility in Australia capable of performing the deperming function.
HMAS Newcastle is the first surface fleet unit to enter the Magnetic Treatment Facility since the facility underwent a period of maintenance and upgrade in February/March 2013.
[mappress] Press Release, May 15, 2013; Image: Australian Navy