In the US, most merchant ship's masters work their way up the ranks, they rarely come from a military background. They may have gone to the Merchant Marine Academy at King's Point, but they are well-prepared by training, examination, and time in grade regulations administered by the Coast Guard. On American naval vessels, most nautical duties are carried out by subordinate officers, even the navigation is done by enlisted men, under officer supervision. US Navy officers are rarely fully qualified all-around seamen, although they may be experts in one particular field, like engineering, communications, gunnery, etc.

In the US Navy, captains are trained in navigation and seamanship, and they are exposed to it on the job, but they are primarily administrators by the time they are given their own ship. The US Navy has a deliberate philosophy of producing well-rounded generalists, as opposed to highly specialized experts. The real tech experts are senior enlisted men.

However, in the merchant service, US skippers have an excellent reputation. In other countries, I just don't know. Still I can't imagine a company owning a ship like that entrusting it to someone who was barely qualified.

Incidentally, captain is a general term for the master of a vessel, the skipper. In the military, the master may have some other rank, depending on the size and mission of the ship. My destroyer leader was commanded by a Commander (O-5). Smaller ships may have a Lieutenant Commander (O-4) or Lieutenant (O-3) in command. Full Captains (O-6) are either running a capital ship like a carrier or cruiser, a squadron of ships, or have administrative duties ashore. An Army Captain is a relatively junior rank, equivalent to a Navy Lieutenant. A Navy Captain is a big shot, comparable to an Army full Colonel.

The Navy ranks are Ensign (O-1), Lieutenant Junior Grade (O-2), Lieutenant, Lieutenant Commander, Commander, Captain, and three levels of Admiral (O-7 through 9)above that.