Underwater electric potential fields occur due to natural reasons, such as changes in atmosphere, ionosphere, magnetosphere, and movements of water bodies in the ocean, or artificial reasons, such as stray and controlled electric currents, or both. Electric potential fields around ship hulls are mainly generated due to corrosion protection systems and dissimilar materials. The electric field intensity over an impressed current anode of a large cruise ship operating in with seawater with a resistance of 20 0-cm is around 90 mV/cm, whereas it is between 0.4 and 1 mV/cm on a propeller for the same ship. The theoretical field intensities obtained from an impressed current cathodic protection (ICCP) system example on COMSOL are 22.5 mV/cm and between 1.25 and 6.25 mV/cm on the surface of the anode and the propeller, respectively.
Erdogan, Caglar, "Sensor Development to Utilize Underwater Electric Potential (UEP) Fields to Navigate the Underwater Areas of Ship Hulls" (2019). Link Foundation Ocean Engineering and Instrumentation Fellowship Reports. 3.