Modern Navigation Methods

Dead reckoning

 or DR, in which one advances a prior position using the ship's course and speed. The new position is called a DR position. It is generally accepted that only course and speed determine the DR position. Correcting the DR position for leeway, current effects, and steering error result in an estimated position or EP. An inertial navigator develops an extremely accurate EP.

Pilotage

 involves navigating in restricted waters with frequent determination of position relative to geographic and hydrographic features.

Celestial navigation

 involves reducing celestial measurements to lines of position using tables, spherical trigonometry, and almanacs.

Electronic navigation 

Radio navigation

 uses radio waves to determine position by either radio direction finding systems or hyperbolic systems, such asDecca, Omega and LORAN-C.

Radar navigation

 uses radar to determine the distance from or bearing of objects whose position is known. This process is separate from radar’s use as a collision avoidance system

Satellite navigation

 uses artificial earth satellite systems, such as GPS, to determine position