My father was a civilian electrical contractor working for a naval shipyard. The trajectory of my life would indicate that I could have been an electrical worker on a cargo ship. However, the latest in technology on ships do not require them as much, and many of the responsibilities are shared by personnel in the engineering department. Moreover, to cut down on labor costs, many shipping companies do not have this position.
Thus, if you love ships then you ought to consider being a chief engineer aboard one. The engineers are also known as technical officers. They have the responsibility of keeping the ship and its machinery (both the engine and the propulsion system) working smoothly. The machinery is quite complex, and is housed in a congested and confined space.
At an entry level, you can also consider being a trainee engineer officer. This role requires you to observe and to learn on the job, to report to the second engineer, and to help out with tasks (some quite menial, such as preparing coffee or tea at breaks) whenever and wherever possible.
A recent job opening for a ship’s chief engineer position stated that the responsibilities of the person obtaining this position would be that he would have complete responsibility of the engine room and the maintenance of the machinery aboard the ship. He would work in conjunction with the Captain, and sometimes holding an equal rank, so that the physical running of the ship is assured. He would supervise others to guarantee that all maintenance is done efficiently and 
effectively. He would need to keep track of the inventory of supplies and of spare parts, and in keeping the inventory current and accurate. Similarly, he must determine the proper inventories and of their amounts before the departure of the vessel.