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The point system is a common way of identifying the location of contacts relative to the heading of a ship. It is a form of relative bearing. The point system uses 32 evenly spaced imaginary points that circle the ship starting at the forward bow. Individual points sit at intervals of 11.25°, similar to compass bearings. [1]
Image of a loxodrome, or rhumb line, spiraling towards the North Pole. In navigation, a rhumb line, rhumb (/ r ĘŚ m /), or loxodrome is an arc crossing all meridians of longitude at the same angle, that is, a path with constant azimuth (bearing as measured relative to true north).
In nautical navigation the relative bearing of an object is the clockwise angle from the heading of the vessel to a straight line drawn from the observation station on the vessel to the object. The relative bearing is measured with a pelorus or other optical and electronic aids to navigation such as a periscope, sonar system, and radar systems ...
If a navigator is west of the agonic line, then the variation is eastward; the Magnetic North Pole appears to the east of the Geographic North Pole. The farther the navigator is from the agonic line, the greater the variation. The local magnetic variation is indicated on NOAA nautical charts at the center of the compass rose. The magnetic ...
Knowing the time of the observation, and with the data contained in the nautical calendar, it is possible to determine the astronomical coordinates of the observed star. Knowing the coordinates of the observed star and the height above the horizon with which it was observed, we can deduce that the observer's position is located on a circle ...
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, he pulls the chart and chart's card, and makes the indicated corrections on the chart.
For example, the U.S. Navy developed the Ships Inertial Navigation System (SINS) during the Polaris missile program to ensure a reliable and accurate navigation system to initial its missile guidance systems. Inertial navigation systems were in wide use until satellite navigation systems (GPS) became available. INSs are still in common use on ...
Instruments used to plot a course on a nautical chart. In navigation, the course of a watercraft or aircraft is the cardinal direction in which the craft is to be steered. The course is to be distinguished from the heading, which is the direction where the watercraft's bow or the aircraft's nose is pointed.