Signature management to reduce sea mine threats.

"For nearly a century, sea mines have been a part of maritime warfare."

  • Underwater sea mines can sense a ship by the changes it makes in its immediate underwater environment, its multi-influence signature (MIS).
  • This risk can be reduced by measuring and analysing a ship’s signatures.
  • We developed the MK III MIS system to measure a ship’s signature and therefore help reduce the risk of sea mines to RNZ Navy ships.

Modern sea mines are activated by influence rather than contact. They can sense a target ship by monitoring for changes in the ambient underwater environment. All ships cause changes, to some extent, in this ambient field. The changes coming from the presence of a naval ship can be minimised by effectively managing its so-called multi-influence - acoustic, pressure, magnetic, electric and seismic - signature (MIS).

This susceptibility of individual ships to the detection and destruction by magnetic influence mines can be reduced by measuring a ship’s underwater signature and then implementing an appropriate signature management and reduction strategy. One of the measures used to minimise this risk to vessels is called ranging and treatment. Ranging typically involves the vessel passing over or through a set of submerged sensors. The results are recorded and analysed, and then measures are put in place to address elements of the vessel’s signature that are seen as a risk.

Our role in measuring ship signatures

Over a number of years, the Defence Technology Agency (DTA) has developed the latest MIS system, the MK III MIS System. This is a two-man deployable, multi influence sensor system consisting of four major sections:

  • seabed sensor frame – four-legged fibreglass frame with an aluminium waterproof housing that contains the seabed computer and electronics to drive the on-board sensors.
  • surface float – anchored to the seabed, the surface float holds four 24-volt battery pods to power the system, an interface pod containing the top end system electronics, cable interface and wireless data link for data transfer to either the support or ranging vessel
  • shipboard components and navigation - includes twin antennas to receive monitoring data from the sensor frame and a laptop to display the data and control the system.
  • system software and data analysis – we developed recording software to collect influence and navigation data collected from ship ranging. Our scientists currently analyse the data but we are working to automate this analysis in a short time so that any adjustments to ships systems to reduce signature anomalies can be undertaken and the ship rechecked within hours rather than days.


Caption: MK III sensor frame

The MK III System collects signature data when a ship passes over the underwater sensor frame positioned on the sea floor. Measuring sensors on the frame are connected to a surface platform, which provides power and recording equipment, by an umbilical cable. Data is relayed from the surface platform to the support ship. And from this data we can determine the ship’s signature and take the appropriate measures to manage any anomalies.


Caption: Surface float