This article presents the development of a UAV system designed to perform visual inspections and thickness measurements in ships’ cargo tanks. That includes the conception and evolution of the different components and subsystems of this UAV system and several tests, including some carried out in actual operating conditions. It also presents a near-wall positioning and propulsion system designed and developed to improve stability and avoid collisions. The paper also describes an articulated arm designed around an EMAT probe for wall thickness measurement. The measurement chain developed for this purpose includes all the electronics and computing necessary to send data in real-time to a ground station. Flying near walls poses challenges that compromises accuracy when approaching each measurement target points. Therefore, the wall approach and departure flight maneuvers are fully automatic. That facilitates and speeds up the inspection task that may require measurements on thousands of locations specified by the surveyor. The proposed UAV system aims to automate and improve the long and expensive surveys and inspections in the marine industry by reducing their time and costs.