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Navigation and location of the ship by geopositioning techniques based on the observation of the stars and other celestial bodies. The variables measured to find the location are: the observed angular height of the stars above the horizon , measured with the sextant (formerly with the astrolabe or other instrument), and the time , measured with ...
Aboard ship a dead reckoning plot is considered important in evaluating position information and planning the movement of the vessel. [8] Dead reckoning begins with a known position, or fix, which is then advanced, mathematically or directly on the chart, by means of recorded heading, speed, and time. Speed can be determined by many methods.
Inertial systems are devices that measure a vessel position over time with motion sensors and gyroscopes. These devices estimate future positions based on velocity, acceleration, and orientation measurements. Detected anomalies that stray from the expected pattern can be flagged for closer inspection.
The system works by triangulating the ship's position based on directional reference to known transmitters. Global Positioning System (GPS) : GPS was designed by the US military with the primary purpose of addressing "drift" within the inertial navigation of Submarine-launched ballistic missile (SLBMs) prior to launch.
Acoustic location is a method of navigation by the use of acoustic positioning systems which determine the position of an object by using sound waves. It is primarily used by submarines and ships fitted with sonar and similar transducer based technologies.
Examples of vessel types that employ DP include ships and semi-submersible mobile offshore drilling units (MODU), oceanographic research vessels, cable layer ships and cruise ships. The computer program contains a mathematical model of the vessel that includes information pertaining to the wind and current drag of the vessel and the location of ...
The fourth and final stage of voyage planning is the monitoring stage. 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, celestial navigation, pilotage, and electronic navigation.
Radar ranges and bearings can be very useful for navigation. Radar navigation is the utilization of marine and aviation radar systems for vessel and aircraft navigation.When a craft is within radar range of land or special radar aids to navigation, the navigator can take distances and angular bearings to charted objects and use these to establish arcs of position and lines of position on a ...