Corrosion related electric (UEP) and magnetic fields (CRM) have an important role in the design of naval vessels and their associated signatures.

The design of a cathodic protection system is of great interest to defence organisations, not only to ensure the integrity of the vessel, but also because it contributes to the electric and magnetic signature of the vessel.

Electo magnetic signatures are playing an important role in the detection of naval vessels and in the fusing of intelligent mines.  The static electric signature is the electric field associated with the DC corrosion or cathodic protection current which flows through the sea water around a vessel.  This is sometimes referred to as the Underwater Electrical Potential or UEP.  The corrosion related magnetic (CRM) field is the coupled magnetic field caused by the corrosion related electric currents flowing in the sea water between the anodes and the ship hull.

It is important to note that UEP and CRM signatures exist even in the absence of a cathodic protection system.  They are caused by the galvanic potential differeces between the metallic structures in contact with the sea water.  For example, the relative position in the electrochemical table of steel and bronze provides a sufficient driving potential to create an electric field.

In order to control the signatures and to preserve the integrity of a vessel, it is essential to be able to predict the impact of the design and operation of the Cathodic Protection system on the electric and magnetic fields.

BEASY can predict the electric fields flowing through the sea water surrounding a ship and the associated magnetic fields.

Predicted Electric and Magnetic Signatures Below the Vessel

BEASY is widely used by defence organisations worldwide to predict the performance of cathodic protection systems and to minimise the associated signatures. BEASY works by modelling the electrochemistry on the metal surfaces and the electric fields in the sea water surrounding the vessel using the boundary element method.  

In applications where the control of the ICCP system is to be modelled, the simulation also includes a model of the control system (e.g. PID).

The BEASY corrosion and magnetic field software provides, in one detailed model, an integrated approach to predicting the:

 

Signature Optimisation

BEASY has an optimisation tool which enables the search for the best design to be highly automated. The user can, for example, define that the objective of the simulation is to achieve a minimum signature whilst at the same time maintaining the required protection potentials on the hull. BEASY will automatically search for the best design to achieve this.

Display of the Electric Field on the Sea Surface

 

Using the BEASY signature management tools the engineer can:

UEP and CRM Prediction

Both the Underwater Electric Potential (UEP) and the Corrosion Related Magnetic (CRM) field are predicted by the software. The impact of the signature of changes in the Cathodic Protection system design, depth of the sea water, sea bed resistivity and the condition of the vessel can be predicted.

Predicted Electric Signature Contour Plot Below the Vessel