The coxswain is the person in charge of a boat, particularly its navigation and steering. The etymology of the word gives a literal meaning of "boat servant" since it comes from cock, a cockboat or other small vessel kept aboard a ship, and swain, an Old English term derived from the Old Norse sveinn meaning boy or servant.
Rowing
In rowing, the coxswain sits in either the bow or the stern of the boat while verbally and physically controlling the boat's steering, speed, timing and fluidity. The primary duty of a coxswain is to ensure the safety of those in the boat. In a race setting, the coxswain is tasked with motivating the crew as well as steering as straight a course as possible to minimize the distance to the finish line. Coxswains are also responsible for knowing proper rowing technique and running drills to improve technique. A coxswain is the coach in the boat, in addition to following the orders of the team coach, the coxswain is connected to the way the boat feels, what's working, what needs to be changed, and how. A successful coxswain must keep track of the drill, time, pace, words of the coach, feel of the boat, direction of the boat, and safety. During a race, a coxswain is responsible for steering, calling the moves, and responding to the way the other boats are moving. Success depends on the physical and mental strength of the rowers, ability to respond to the environment, and the way in which the coxswain motivates the rowers, not only as individuals but as members of the crew.
In the United States Coast Guard and United States Coast Guard Auxiliary, the coxswain is the person in charge of a small boat. The coxswain has the authority to direct all boat and crew activities during the mission and modify planned missions to provide for the safety of the boat and the crew. Before a person can be assigned to be a coxswain, they have to go through a qualification procedure, be certified and maintain the certification to be a coxswain. Upon certification, they are awarded the Coxswain Badge. This qualification procedure requires a significant amount of practice in boat handling as well as previous experience as a boat crew member. Any Coast Guardsman may become a coxswain upon proper qualification. An advancement to boatswain's matesecond class requires that the individual qualify as and maintain certification as a coxswain. A commanding officer or officer in charge of a land based unit with boats has to be certified and stay certified as a coxswain on all boats in the unit or be relieved of command. A coxswain is assigned to a boat by the command authority and can only be relieved by the commanding officer/Officer in Charge, executive officer/Executive Petty Officer, or senior officer present. The coxswain’s authority is independent of rank and/or seniority in relation to any other person on board the boat. Unlike the commanding officer of a cutter or ship, a coxswain does not automatically have command authority.