Captain is the traditional customary title given to the person in charge of a ship at sea.
On most legal documents in the merchant shipping industry, the captain is more formally referred to as the ship's Master. A nautical "captain" may be a civilian with a master's license or a naval commissioned officer of any rank. In most modern navies, the rank of captain is equivalent to the army rank of colonel, and is thus three ranks higher than army captain.
On shore, a Harbourmaster, as the equivalent chief of a port, is sometimes titled "captain" if he had merchant marine or naval rank and professional service in command at sea. Many shipping companies also hire experienced captains to run their operations department.
A person holding an unrestricted master's license (or certificate) is called a Master Mariner, and may use the postnomial MM. The term unrestricted indicates that there is no restriction of size, power or geographic locale on the license. It is the highest level of professional qualification amongst mariners.
Among professional mariners, the title "Captain" is generally reserved for someone who has served in command of a merchant vessel, and not for someone who may hold a command license but has never been appointed to a command position. Captains retain the title while working in a maritime related field ashore.
The term Master Mariner was in use in England from at least the 13th century—reflecting the fact that in guild terms, such a person was a master craftsman in this specific profession—and was introduced in America in the mid-19th century.
An unrestricted master's license is colloquially called a "Master's Ticket", "Master's Unlimited" or just a "Master's." In the UK the official name of a Master Mariner’s qualification has varied over the years. The conventions or acts governing the license have evolved alongside the shipping industry. The master's license is sometimes still referred to as a Class 1 or Master Foreign-Going certificate as it was named during the latter part of the 20th century. The UK Maritime & Coastguard Agency, inline with the amended STCW convention, currently title the license as Master Unlimited.
The captain has enormous legal powers and is responsible in all aspects for a ship underway. Powers include the right to use deadly force to suppress piracy and mutiny. It was a myth that any captain can conduct a marriage. However this can now be done on Bermudan-flagged ships in international waters. The Master must hold a Marriage Officers License, valid on a designated ship, in order to do this, which is issued by the Minister of Labour, Home affairs and Public Safety in Bermuda. Any captain of the ship registered in Czech Republic can conduct a marriage when sailing in international waters.
At sea, the captain enjoys absolute command. This authority holds true even if higher-ranking persons are aboard. If a higher-ranking person gives the captain an order, care is taken to specify what is desired rather than how to do it. Rank does not give the right to interfere in the captain's running of the ship.
There is also an unwritten responsibility that the captain must be the last one to evacuate the ship. This has led to the recurring theme that the captain goes down with the ship, displayed in popular movies such as Titanic.
Most importantly, the captain has the moral responsibility towards all his or her ship mates' health, safety as well as wellbeing. In today's world very few professions hold so much power and responsibility. The range of responsibilities includes which navigational route to take, what items to purchase from next port, whether to dismiss a shipmate for his or her incompetence, or even what should be on the dinner menu for the whole ship.
The traditional sleeve emblem for captains is four gold stripes (often called "rings") on the lower sleeve or shoulderboard. Many navies follow the precedent of the Royal Navy and have an "executive loop" on the top or inner ring. Often harbormasters have a fouled anchor or other local symbol on the gold rings. A slang term often used by crew is 'candy bars', one 'candy bar' for the 3/o, two for the 2/o and so on.
Uniform is still worn on many ships at sea, but generally these days only on the larger and more traditionally run vessels. It is not unusual for Ships Officers to have to dress in uniform to go into the wardroom after a certain time of day and it is still expected for entry into the saloon for dinner. A rigid show of hierarchy is still often desired on many vessels due to the fact that many are run with third world crew but western Officers. This 'visible show' of rank is a reminder of seniority and superiority to the crew who are expected to show a good response to orders at all times. Unifrom at sea will consist of black trousers, black shoes, white pilot shirt and epaulettes denoting rank. Full uniform involving a reefer jacket and hat is rarely worn other than at remembrance services, marriages and such like.
In the passenger-carrying trade a unified corporate image is often desired and it is useful for those unfamiliar with the vessel to be able to identify members of the crew and their function. In this case, captains on duty usually wear the four stripes and rings with the traditional emblem or design of their particular shipping company or vessel’s nationality. Some companies and countries do have an "executive loop" similar to that of the Royal Navy. The Captain and Officers on British ships often wear the traditional diamond shape within the stripes. This loop represents the wake of a ship's propeller. It should be worn on the correct direction. The over lapping loop should always be facing forward. Most captains in the United States do not wear a uniform unless they are in the Merchant Marine Reserve.
The officer who is ranked immediately below the captain of a ship is designated the chief mate, chief officer, or first officer (also executive officer on naval vessels or staff captain on large passenger vessels). The chief mate is responsible for implementing the orders of the captain as well as conferring with the captain on matters concerning the ship. The "second in command" is typically responsible (along with the senior enlisted petty officer) for maintaining minor discipline on the ship as well as the vessel's cargo, stability and maintenance. The second mate (navigational officer), the third mate (safety officer), and the boatswain (crew foreman) are ranked below the chief mate.
In older times, a captain was a nobleman given responsibility over a ship, but was not likely to have any nautical experience. The next officer of the ship would be the ship's master. The master carried out the executive functions of a captain, while the titular captain filled a ceremonial and legal role.
In the Royal Navy in the days of sail, "master" was often used as an abbreviation for the Sailing Master, the warrant officer responsible for the navigation and steering of the vessel. The position of sailing master was later commissioned and renamed the Navigating Officer. The Navigating Officer on a flagship, however, continued to be known as the Master of the Fleet until after the Second World War. The sailing master would call out to the men working the sails to move them a certain direction. This moved the sails at such an angle that the vessel moved towards the sailing master's request.
A ship's master was a wardroom officer. A ship's most senior warrant officers, those who headed the ship's technical departments, received their warrants from various Boards and Commissions. Their appointment and promotion did not lie within the Captain's discretion. The rate of the more junior crew members did lie within the captain's discretion—even midshipmen.
The Master's Mates were the assistants to the Sailing Master, also warrant officers. These were usually young men with family connections not quite good enough to become midshipmen who either aspired to become sailing masters themselves or to be commissioned as lieutenants, as often happened. Fletcher Christian was Master's Mate on HMS Bounty.
Master and Commander was the full title of the rank held by Commanders when they were first introduced into the Royal Navy, then equivalent to a major in the British Army. This title formed the basis for the historical novel Master and Commander. The title was shortened to commander in 1814. The corresponding title in the U.S. Navy was "Master Commandant".