Navigational instrument

Navigational instruments are essential tools utilized by nautical navigators and pilots in their profession. The core objective of navigation is to determine the current location, assess speed and direction, and navigate to the designated port or destination.

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Marine Charts and Drafting Instruments

• Charts: These are maps detailing navigable areas with specific marine information.
• Computing aids: Involved in mathematical calculations. Modern-day aids include electronic computers or calculators, while traditional aids consisted of tables (trigonometric, logarithmic, etc.) and slide rules.
• Dividers: Used to ascertain lengths of lines and approximate distances of non-linear paths on a chart.
• Nautical almanac: Helps determine the position of celestial bodies after observations.
• Parallel rules: Transferring lines to parallel positions and comparing orientations on a compass rose.

Direct Measurement Tools

• Chip log and sand glass: Measure the ship's speed through the water.
• Sounding line: Measures water depth and retrieves seabed samples.
• Drift meter: Optically gauges the wind's effect on a ship or aircraft in motion.

Position Finding Equipment

Celestial Navigation Tools

These instruments measure the altitude of celestial objects:

• Back staff: Notably Davis' quadrant; measures the Sun's altitude indirectly.
• Cross staff: An antiquated tool no longer in use.
• Kamal: A basic Arabian tool involving a board and knotted string for angle measurements.
• Mariner's astrolabe: 15th-century tool replaced by back staff, octant, and sextant.
• Quadrant: Simple instrument using a plumb bob for measurements.

These tools measure angular distances between objects:

• Octant: Invented in 1731, measures angles accurately despite motion.
• Sextant: Evolved from the octant in 1757, rendered previous instruments obsolete.

Bearing Tools

• Pelorus: Determines bearings relative to the ship's heading, landmarks, or other ships.

Navigational Compasses

• Bearing compass: Measures magnetic bearings of landmarks, other ships, or celestial bodies.
• Magnetic compass: Determines the magnetic heading of the vessel.

Timekeeping Instruments

• Marine chronometer: Determines prime meridian time with high precision essential for celestial navigation.
• Nocturnal: Determines local time by observing Polaris and nearby stars.
• Ring dial: Measures celestial body's altitude to find local time or altitude of the Sun.

Traditional instruments mentioned were used until the mid-20th century. Post-World War II saw rapid development of electronic aids, often replacing traditional tools. Instruments like GPS have made old technologies like LORAN obsolete.

Electronic Navigation Aids for Visually Impaired

Innovations in technology have extended to Electronic Travel Aids (ETAs) designed for individuals with visual impairments. Beyond GPS, other technologies such as infrared sensors, ultrasonic sensors, and cameras have been developed to help the visually impaired navigate and identify obstacles, enhancing their mobility.

See Also

References

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1. Li, Kun. Electronic Travel Aids for Blind Guidance. Sutardja Center for Entrepreneurship & Technology, Berkeley, California, 2015, pp. 1–10.
2. Patra, Rusha, et al. “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

Modern Navigational Instruments for Ships