Hull corrosion is primarily caused by the deterioration of protective coatings. Given that inspections of hulls are both time-consuming and labor-intensive, thereby conducted infrequently, this study aims to propose a rapid detection and localization method for hull coating damage. Using the changes about underwater electric potential caused by the impressed current cathodic protection system and coating damage, the location of the damage can be identified by measuring the potential difference underwater at symmetrical positions on the hull. Underwater electric field transmission experiments have confirmed the feasibility of methods for ranging and locating fault positions based on electric field characteristic signals. Additionally, COMSOL Multiphysics simulation software was utilized to model the corrosion electric field generated by the cathodic protection current and the electrochemical corrosion processof metallic surfaces on the hull.By analysing the potential variation along the measurement segments on both sides of the hull, it is observed that the underwater potential difference is notably largest around the damaged coating area.Based on the transmission characteristics of the underwater electric field, longitudinal and transverse positioning of the damage points have been achieved, with average deviations of 0.2 m and 0.21 m. Moreover, a linear relationship between potential magnitude and damaged area was observed. This method offers high accuracy and is suitable for longitudinal positioning of multiple points with intervals greater than 3 m. It mitigates environmental factors’ interference with detection, enabling early and rapid detection of hull coating damage and improving corrosion management for vessels.