Measurement and Model Predicted Corrosion Related Magnetic Signature: Applied on CFAV Quest

摘要

In simple terms the corrosion related magnetic (CRM) field arises due to the flow of corrosion currents through the sea water. This current density has many sources with one of the most prominent being the currents that arise due to the corrosion of the metal work of the ship. Various corrosion countermeasures, for example an impressed current cathodic protection (ICCP) system, also directly affect the current density and hence an accurate model of the electromagnetic signatures can provide crucial information about the level of corrosion on the ship. Computer models based on finite or boundary element methods have been used for some years to predict the electric and magnetic signatures of vessels created by their cathodic protection (CP) systems. The literature presents good agreements between the electric field values obtained from the computer models and from the measurements on physical scale models or even on the real ships. However, at this time corrosion-related magnetic (CRM) signatures have only been predicted and no reference is made to the accuracy of such calculations. This report describes the theoretical background of the CRM signature calculation, and compares the model prediction with the measured CRM signature of the Canadian research vessel CFAV Quest.