What Forms of Navigation Are Used Today in Ships of Iron & Steel?

The early days of boat navigation were simple. Believing the Earth was flat kept most ships' captains within sight of land, allowing mariners to use landmarks as navigation aids. As exploration and scientific knowledge proved the Earth was round, the need to tell direction while surrounded on all sides by water became critical. Electronic navigation devices are essential for use on both recreational and commercial ships but most ships maintain non-electronic devices aboard for back-up in an emergency.

  1. Celestial Navigation

    • Using the stars, sun and moon to navigate is the oldest means of navigation on land and sea. By determining the angle between the horizon and a celestial object, sailors can calculate distance and direction. A sextant is the instrument used for celestial navigation.

    Compasses

    • The primary and simplest form of navigation on ships is a magnetic compass. Able to tell direction from anywhere on Earth and with limited technology, the compass is the most basic and probably the oldest navigation instrument, with origins in 200 B.C China. In the early 20th century, the gyroscopic compass came into use. The gyro compass always points to true north and uses gravity to turn a gyrowheel.

    Radar

    • Realizing a need to navigate at night and to detect other vessels, the military developed radio detection ranging (Radar) in the 1930s. Still used today, Radar sends out radio waves that reflect distant objects. The bounced signals are measured to determine distance to an object. Radar is useful in cloudy or foggy conditions when visibility is severely limited.

    Loran

    • Long Range Navigation systems, or LORAN, are systems using low frequency radio waves sent from stations on land. Timed intervals between signals determine ship positions. This system shows accuracy in increments of hundreds of yards but has been replaced in most ships by more technologically advanced systems.

    GPS

    • Developed by and originally used by the United States military, global positioning systems (GPS) have become the standard of navigation for ships, cars and people. A GPS uses signals from orbiting satellites to tell position and has an accuracy to within 30 feet.

    Charts

    • Maps of oceans, bays and other waterways indicate depth, channel markers, buoys and other navigation stations. Nautical charts also show land outlines and nautical miles between points. The National Oceanic and Atmospheric Administration produces the charts. When electronic systems fail to function, a chart is an essential back up for use with compasses and other navigation aids.

    Buoys

    • Physical markers set in rivers, bays and the entrances to harbors help a ship navigate using sight. Floating buoys are anchored in place and indicated on charts and electronic devices. They mark channel entrances and are colored either red or green. When returning to the harbor, keep the red marker to the right, when leaving, the green marker is kept to the right. Most have lights for night navigation and some have bells that ring as they are rocked by waves, indicating position by sound.

    Lighthouses

    • Lighthouses used to be critical components to ship navigation, but they are no longer nativational mainstays. Primarily used to aid ships in marking coastlines, dangerous rocks and shoals, lighthouses have been replaced with electronic devices.. But lighthouses, though now normally automated, still use beacons and light to mark coastal hazards and harbor entrances.