A lot of people ask me, "Is it hard to be an engineer on a ship?" And I say: it is hard, but just as much, it is educational. Being a Third Engineer, especially, is a unique experience... because you are right in the middle of the engineering hierarchy on the ship. You support the newly arrived Fourth Engineer and, at the same time, ease the load of the Chief and Second Engineer. You're like the ship's interface software; everyone throws data at you, and you process it to keep the system running.
The first thing I do when I wake up in the morning is go down to the engine room. The ship doesn't sleep; the engines never stop. Even if you complete your watch, they keep working. During the watch, pressure, temperature, oil levels, pumps, purifiers (separators)... everything passes before my eyes. Sometimes the machines I tell, "Come on, boy, don't give me trouble today," deliberately act up and can wake me up at 3 AM with an alarm. :D
The Third Engineer is generally responsible for the auxiliary machinery. This means the pumps, compressors, and purifiers are like your babies. You feed them, clean them, oil them, and sometimes you have to dismantle and reassemble them... otherwise, they start crying (or sounding an alarm). :D
When you are at sea, weather conditions, the intensity of the ship's operations, and sometimes unexpected breakdowns make your life difficult. If a purifier breaks down in the middle of the ocean, you don't have the luxury of saying, "Let the technician come and fix it." You have to do it. That's why manual skills, practical intelligence, and patience are worth their weight in gold here.
But the job also has its good sides. For one, the engine room is a different world. Although it might look a bit like hell with its noise, oil, and heat, you feel powerful in there. When you solve a breakdown and get the ship back underway, you feel like a hero to yourself. :D
Also, as a Third Engineer, you now have responsibility. You are not a cadet, but you don't carry the burden of the Chief Engineer either. You are in a balanced position. Of course, there is the human side of the job, too. Building good relationships with the crew is crucial. The ship is like a small village. If you don't get along with people, you'll make it hell for yourself. And don't forget: as a Third Engineer, you are sometimes a role model for the youngsters, sometimes a helper to the seniors, and sometimes the repairman for the coffee machine. :D
In conclusion, being a Third Engineer is a total balancing act. On one hand, responsibility; on the other, an opportunity to learn and develop yourself. Things you might never see in a lifetime of engineering ashore, you learn in just a few contracts at sea. And the best part of the job, in my opinion, is this: The sea teaches you both patience and freedom at the same time.