Navigational instruments are

instruments Instrument may refer to: Science and technology * Flight instruments, the devices used to measure the speed, altitude, and pertinent flight angles of various kinds of aircraft * Laboratory equipment, the measuring tools used in a scientific lab ...

used by nautical navigators and pilots as tools of their trade. The purpose of navigation is to ascertain the present

position Position often refers to: * Position (geometry), the spatial location (rather than orientation) of an entity * Position, a job or occupation Position may also refer to: Games and recreation * Position (poker), location relative to the dealer * ...

and to determine the speed, direction, etc. to arrive at the port or point of destination.

Charts and drafting instruments

Charts A chart (sometimes known as a graph) is a graphical representation for data visualization, in which "the data is represented by symbols, such as bars in a bar chart, lines in a line chart, or slices in a pie chart". A chart can represent tabul ...

are maps of the areas to be navigated with details specific to the marine environment. *Computing aids: used in the necessary mathematical calculations. Today electronic

computers A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These programs ...

calculators An electronic calculator is typically a portable electronic device used to perform calculations, ranging from basic arithmetic to complex mathematics. The first solid-state electronic calculator was created in the early 1960s. Pocket-size ...

are used. Other traditional aids used included tables (trigonometric, logarithms, etc.) and slide rules. * Dividers used for measuring lengths of lines and approximate lengths of non-linear paths on a chart. * Nautical almanac used to determine the position in the sky of a celestial body after a sight has been taken. * Parallel rules used for transferring a line to a parallel position. Also used to compare the orientation of a line to a magnetic or geographic orientation on a compass rose.

Direct measuring

* Chip log and

sand glass Sand art is the practice of modelling sand into an artistic form, such as sand brushing, sand sculpting, sand painting, or creating sand bottles. A sandcastle is a type of sand sculpture resembling a miniature building, often a castle. The dr ...

serve to measure the ship's speed through the water. * Sounding line used to measure the depth of the water and to pick up samples from the bottom. * Drift meter optically measures the effects of wind on an aircraft in flight.

Position finding instruments

Celestial navigation instruments

These instruments are used primarily to measure the elevation or altitude of a celestial object: *

Back staff The backstaff is a navigational instrument that was used to measure the altitude of a celestial body, in particular the Sun or Moon. When observing the Sun, users kept the Sun to their back (hence the name) and observed the shadow cast by the up ...

, the best known of which is the Davis' quadrant. It could measure the altitude of the sun without having the navigator directly observe the sun. *

Cross staff The term Jacob's staff is used to refer to several things, also known as cross-staff, a ballastella, a fore-staff, a ballestilla, or a balestilha. In its most basic form, a Jacob's staff is a stick or pole with length markings; most staffs ar ...

, an older instrument long out of use. * Kamal Very simple instrument used primarily by Arabian navigators. It consists of a small board with a knotted piece of twine through the center. The observer holds one of the knots in his mouth and extends the board away so that the edges make a constant angle with his eyes. * Mariner's astrolabe Derived from the

astrolabe An astrolabe ( grc, ἀστρολάβος ; ar, ٱلأَسْطُرلاب ; persian, ستاره‌یاب ) is an ancient astronomical instrument that was a handheld model of the universe. Its various functions also make it an elaborate inclin ...

, it was developed in late 15th century and found use in the 16th to 17th centuries. It was replaced by the

back staff The backstaff is a navigational instrument that was used to measure the altitude of a celestial body, in particular the Sun or Moon. When observing the Sun, users kept the Sun to their back (hence the name) and observed the shadow cast by the up ...

and later by the octant and

sextant A sextant is a doubly reflecting navigation instrument that measures the angular distance between two visible objects. The primary use of a sextant is to measure the angle between an astronomical object and the horizon for the purposes of celes ...

. * Quadrant A very simple instrument which used a plumb bob. These instruments are also used to measure the angular distance between objects: * Octant, invented in 1731. The first widely accepted instrument that could measure an angle without being strongly affected by movement. *

Sextant A sextant is a doubly reflecting navigation instrument that measures the angular distance between two visible objects. The primary use of a sextant is to measure the angle between an astronomical object and the horizon for the purposes of celes ...

, derived from the octant in 1757, eventually made all previous instruments used for the same purpose obsolete.

Bearing instruments

* Pelorus used to determine bearings relative to the ship's heading of landmarks, other ships, etc.

Compasses

Bearing compass A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with ...

used to determine magnetic bearings of landmarks, other ships or celestial bodies. * Magnetic compass used to determine the magnetic heading of the ship.

Timekeeping

* Marine chronometer used to determine time at the prime meridian with great precision which is necessary when reducing sights in celestial navigation. *

Nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

used to determine apparent local time by viewing the

Polaris Polaris is a star in the northern circumpolar constellation of Ursa Minor. It is designated α Ursae Minoris ( Latinized to ''Alpha Ursae Minoris'') and is commonly called the North Star or Pole Star. With an apparent magnitude that ...

and its surrounding stars. * Ring dial or astronomical ring used to measure the height of a celestial body above the horizon. It could be used to find the altitude of the sun or determine local time. It let sunlight shine through a small orifice on the rim of the instrument. The point of light striking the far side of the instrument gave the altitude or tell time. All those mentioned were the traditional instruments used until well into the second half of the 20th century. After World War II electronic aids to navigation developed very rapidly and, to a great extent, replaced more traditional tools. Electronic speed and depth finders have totally replaced their older counterparts. Radar has become widespread even in small boats. Some Electronic aids to navigation like LORAN have already become obsolete themselves and have been replaced by

GPS The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...

Electronic Travel Aid

As technologies are developed, designers and engineers have also turned their attention to minority groups like people that are visually impaired. In this case , Electronic Travel Aid are developed to target the needs of visual impaired individuals for obstacle identification as well as navigation of the surrounding to enhance mobility. Not only GPS systems, there are other approaches like infrared sensors, ultrasonic sensors as well as optical technologies like cameras that are developed/ developing to enhance the navigation of the minority group.Patra, Rusha, et al. “(PDF) an Electronic Travel Aid for Navigation of Visually Impaired Persons.” ResearchGate, Feb. 2011, https://www.researchgate.net/publication/224219996_An_electronic_travel_aid_for_navigation_of_visually_impaired_persons.

References

External links

How to use the dividers

Navigational Instruments at The Mariners' Museum
{{DEFAULTSORT:Navigational Instrument Navigation Navigational equipment