2nd Capt Qr Deck Man would be a seaman on the Quarter Deck.
Over him would be a 2nd Capt Qr Deck and then a Capt Qr Deck (Watch Captain).
A Watch Captain is a Shipboard appointment by captain, and an Experienced seaman in charge of a watch team.
https://en.wikipedia.org/wiki/Royal_Navy_ranks,_rates,_and_uniforms_of_the_18th_and_19th_centuries"Watch organization
Royal Navy vessels operated on a number of parallel hierarchies in addition to formal ranks and positions, paramount of which was the vessel's watch organization. Watches were stood 24 hours a day and divided into "watch sections" each of which was led by an "officer of the watch", typically a lieutenant, midshipman, or master's mate (the captain and master did not stand watch but were on call 24 hours a day)
The heart of the watch were the watch teams, each led by a petty officer known as a captain (separate entirely from the vessel's commanding officer). There were six watch teams on most Royal Navy vessels, divided into three "deck" teams and three "aloft" teams. The aloft teams were manned by sailors known as "topmen" and were considered the most experienced men aboard. In all, the six watch teams were as follows:
Aloft: Fore topmen, main topmen, mizzen topmen
Deck: Forecastle men, waisters, afterguard
A special watch team of quartermasters handled the navigation and steering of the vessel from the quarterdeck. Furthermore, the ship's boatswain and his mates were interspersed among the various watch teams to ensure good order and discipline. The remainder of the ships' company, who did not stand a regular watch, included the ship's carpenter's crew and the gunnery teams (in charge of the maintenance of the ship's guns). Any other person on board who did not stand watch was collective referred to as an "idler" but was still subject to muster when the "all hands on deck" was called by the boatswain."
Tony