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A navigator is the person on board a ship or aircraft responsible for its navigation.Grierson, Mike. Aviation History—Demise of the Flight Navigator, FrancoFlyers.org website, October 14, 2008. Retrieved August 31, 2014. The navigator's primary responsibility is to be aware of ship or aircraft position at all times. Responsibilities include planning the journey, advising the ship's captain or aircraft commander of estimated timing to destinations while en route, and ensuring hazards are avoided. The navigator is in charge of maintaining the aircraft or ship's , nautical publications, and navigational equipment, and they generally have responsibility for meteorological equipment and communications. With the advent of satellite navigation, the effort required to accurately determine one's position has decreased by orders of magnitude, so the entire field has experienced a revolutionary transition since the 1990s with traditional navigation tasks, like performing celestial navigation, being used less frequently. Using multiple independent position fix methods without solely relying on electronic systems subject to failure helps the navigator detect errors. Professional mariners are still proficient in traditional piloting and celestial navigation.
Aboard ships in the Merchant Marine and Merchant Navy, the second mate is generally the (senior) navigator.
The nature of a waterway depicted by a chart changes regularly, and a mariner navigating on an old or uncorrected chart is courting disaster. Every producer of navigational charts also provides a system to inform mariners and aviators of changes that affect the chart. In the United States, chart corrections and notifications of new editions are provided by various governmental agencies by way of Notices to Airmen (NOTAMs), Notice to Mariners, Local Notice to Mariners, Summary of Corrections, and Broadcast Notice to Mariners. Radio broadcasts give advance notice of urgent corrections.
A convenient way to keep track of corrections is with a "chart and publication correction record card" system. Using this system, the navigator does not immediately update every chart in the portfolio when a new Notice to Mariners arrives, instead creating a card for every chart and noting the correction on this card. When the time comes to use the chart, the navigator pulls the chart and chart's card, and makes the indicated corrections on the chart. This system ensures that every chart is properly corrected prior to use. British merchant vessels receive weekly Notices to Mariners issued by the Admiralty. When corrections are received all charts are corrected in the ship's folio and recorded in NP133A (Admiralty Chart Correction Log and Folio Index). This system ensures that all charts are corrected and up to date. In a deep-sea vessel with a folio of over three thousand charts this can be a laborious and time-consuming task for the navigator.
Various and diverse methods exist for the correction of electronic navigational charts.
The nature of waterways described by any given nautical publication changes regularly, and a mariner navigating by use of an old or uncorrected publication is courting disaster. Every producer of nautical publications also provides a system to inform mariners of changes that affect the chart. In the United States, corrections and notifications of new editions are provided by various governmental agencies by way of Notice to Mariners, Local Notice to Mariners, Summary of Corrections, and Broadcast Notice to Mariners. Radio broadcasts give advance notice of urgent corrections. For ensuring that all publications are fully up-to-date, similar methods are employed as for nautical charts. Various and diverse methods exist for the correction of electronic nautical publications.
Before each voyage begins, the navigator should develop a detailed mental model of how the entire voyage will proceed. In the aviation community, this is known as "chair flying". This mental model includes charting courses and forecasting weather, tides, and currents. It includes updating and checking aeronautical charts, nautical publications, which could include Sailing Directions and Coast Pilots, and projecting the various future events including landfalls, narrow passages, and course changes that will transpire during the voyage. This mental model becomes the standard by which the navigator will measure progress toward the goal of a safe and efficient voyage, and it is manifested in a written passage plan.
When working in a team environment, the passage/mission plan should be communicated to the navigation team in a pre-voyage conference (USAF term is "mission briefing") in order to ensure that all members of the team share the same mental model of the entire trip.
Passage planning procedures are specified in International Maritime Organization Resolutions, in the laws of IMO signatory countries (for example, Title 33 of the U.S. Code of Federal Regulations), and a number of professional books and USN/USAF publications. There are some fifty elements of a comprehensive passage plan depending on the size and type of vessel, each applicable according to the individual situation.
A good passage plan will include a track line laid out upon the largest-scale charts available which cover the vessel's track. The navigator will draw and redraw the track line until it is safe, efficient, and in line with all applicable laws and regulations. When the track is finished, it is becoming common practice to also enter it into electronic navigation tools such as an Electronic Chart Display and Information System, a chartplotter, or a GPS unit.
Once the voyage has begun the progress of the vessel along its planned route must be monitored. This requires that the ship's position be determined, using standard methods including dead reckoning, radar fixing, celestial navigation, pilotage, and electronic navigation, to include usage of GPS and navigation computer equipment.
Passage planning software, tide and tidal current predictors, celestial navigational calculators, consumables estimators for fuel, oil, water, and stores, and other useful applications.
and can use several Global Navigation Satellite Systems (GNSS) to navigate all of the world's lakes, seas and oceans. Maritime GNSS units include functions useful on water, such as "man overboard" (MOB) functions that allow instantly marking the location where a person has fallen overboard, which simplifies rescue efforts. GNSS may be connected to the ships self-steering gear and using the NMEA 0183 interface, and GNSS can also improve the security of shipping traffic by enabling AIS.
The title character of Robert A. Heinlein's 1953 novel Starman Jones is an astrogator.
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