Promotion to the ranks Commander or Captain bore no relationship to the numbers actually required by the Navy, and there was a considerable over-supply of officers in these ranks. Even in wartime it was quite common for Commanders and Captains who lacked influential friends to spend years waiting for a ship to command. They would be stuck on half pay, debarred from taking other employment, and with no opportunity to earn prize money. I've put a link below to a post I made earlier in the GR on this subject.