This paper presents a comprehensive development process of magnetic adhesion modules designed for mobile robots working in shipyards, performing hull-cleaning duties. The main aim is to prepare a secure system that will allow robots to safely navigate on ferromagnetic hulls. Typical process involves sandblasting performed by human personnel, which creates highly dangerous working conditions and requires numerous safety precautions to prevent both human accidents and environmental contamination related to cleaning medium spreading. Delegating this task to robot allows the deployment of specially designed cleaning equipment, reducing accidents’ chance, medium spreading and its usage thanks to dedicated salvage system. Existing literature lacks precise information on magnetic force calculations due to the high complexity of the problem that can be accounted to magnet shape or used materials. This study could be used as a guideline for development of similar equipment. The Finite Element Method Magnetics (FEMM) software is utilized for modelling and simulating numerous solutions that align with the working conditions of the robot. To generate a high-density, low-range magnetic field, which would be highly compatible for working conditions, Halbach array was used and comparison with single magnet of equivalent size was provided. The paper also discusses material choice and geometric considerations for the chassis. Experimental measurements of physical system involved multiple magnets’ configurations. This study provides a thorough comparison of numerical predictions and an actual performance of developed magnetic adhesion modules, establishing a field-tested design that can serve as a valuable reference for future work.