Submarine navigation
Encyclopedia
Submarine navigation underwater requires special skills and technologies not needed by surface ships
. The challenges of underwater navigation
have become more important as submarines spend more time underwater, travelling greater distances and at higher speed. Military submarines travel underwater in an environment of total darkness with neither windows nor lights. Operating in stealth mode, they cannot use their active sonar systems to ping
ahead for underwater hazards such as undersea mountains
, drilling rig
s or other submarines. Surfacing to obtain navigational fixes
is precluded by pervasive anti-submarine warfare
detection systems such as radar
and satellite
surveillance. Antenna masts
and antenna-equipped periscopes can be raised to obtain navigational signals but in areas of heavy surveillance, only for a few seconds or minutes; current radar technology can detect even a slender periscope while submarine shadows may be plainly visible from the air.
Surfaced submarines entering and leaving port navigate similarly to traditional ships but with a few extra considerations because most of the ship rides below the waterline, making them hard for other ships to see and identify.
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Bullseye (target)
The bullseye, or bull's-eye, is the centre of a target , and by extension the name given to any shot that hits the bullseye...
. The challenges of underwater navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
have become more important as submarines spend more time underwater, travelling greater distances and at higher speed. Military submarines travel underwater in an environment of total darkness with neither windows nor lights. Operating in stealth mode, they cannot use their active sonar systems to ping
Acoustic location
Acoustic location is the science of using sound to determine the distance and direction of something. Location can be done actively or passively, and can take place in gases , liquids , and in solids .* Active acoustic location involves the creation of sound in order to produce an echo, which is...
ahead for underwater hazards such as undersea mountains
Seamount
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...
, drilling rig
Drilling rig
A drilling rig is a machine which creates holes or shafts in the ground. Drilling rigs can be massive structures housing equipment used to drill water wells, oil wells, or natural gas extraction wells, or they can be small enough to be moved manually by one person...
s or other submarines. Surfacing to obtain navigational fixes
Fix (position)
In position fixing navigation, a position fix or simply a fix is a position derived from measuring external reference points.The term is generally used with manual or visual techniques such as the use of intersecting visual or radio position lines rather than the use of more automated and accurate...
is precluded by pervasive anti-submarine warfare
Anti-submarine warfare
Anti-submarine warfare is a branch of naval warfare that uses surface warships, aircraft, or other submarines to find, track and deter, damage or destroy enemy submarines....
detection systems such as radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
and satellite
Spy satellite
A spy satellite is an Earth observation satellite or communications satellite deployed for military or intelligence applications....
surveillance. Antenna masts
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
and antenna-equipped periscopes can be raised to obtain navigational signals but in areas of heavy surveillance, only for a few seconds or minutes; current radar technology can detect even a slender periscope while submarine shadows may be plainly visible from the air.
Surfaced submarines entering and leaving port navigate similarly to traditional ships but with a few extra considerations because most of the ship rides below the waterline, making them hard for other ships to see and identify.
Surface and near-surface navigation
On the surface or at periscope depth, submarines have used these methods to fix their position:- Satellite navigation:
- Global positioning systemGlobal Positioning SystemThe Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...
(GPS) - - by entering waypoints internally, able to navigate at a more precise level. - NAVSATTransit (satellite)The TRANSIT system, also known as NAVSAT , was the first satellite navigation system to be used operationally. The system was primarily used by the U.S...
- Global positioning system
- Terrestrial radio-based navigationRadio navigationRadio navigation or radionavigation is the application of radio frequencies to determine a position on the Earth. Like radiolocation, it is a type of radiodetermination.The basic principles are measurements from/to electric beacons, especially...
systems; largely superseded by satellite systems- LORANLORANLORAN is a terrestrial radio navigation system using low frequency radio transmitters in multiple deployment to determine the location and speed of the receiver....
-- seldom if rarely used anymore. - CHAYKACHAYKAChayka is a Russian terrestrial radio navigation system, similar to LORAN-C. It is also run on 100 kHz and is described like LORAN-C by its GRI.-Chayka-Chains:There are 5 Chayka-chains in use:...
, the Russian counterpart of LORAN - OMEGA, the Western counterpart of the Alpha Navigation System, no longer in use
- AlphaAlpha (radio navigation)Alpha is a Russian system for long range radio navigation. RSDN in Russian stands for , i.e., radio-technical long-distance navigation system....
, the Russian counterpart of the Omega Navigation System
- LORAN
- Celestial navigationCelestial navigationCelestial navigation, also known as astronavigation, is a position fixing technique that has evolved over several thousand years to help sailors cross oceans without having to rely on estimated calculations, or dead reckoning, to know their position...
using the periscope, or sextant—seldom used anymore due to advancement in technology - Radar navigationRadar navigationMarine and aviation radar systems can provide very useful navigation information in a variety of situations. When a vessel 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...
; radar signals are easily detected so radar is normally only used in friendly waters entering and exiting ports. With the implementation of a more advanced radar system, many new techniques have been implemented in this process. - Active sonar; like radar, active sonar systems are readily detected, so active sonar is usually used only entering and exiting ports.
- PilotagePilotagePilotage is the use of fixed visual references on the ground or sea by means of sight or radar to guide oneself to a destination, sometimes with the help of a map or nautical chart. People use pilotage for activities such as guiding vessels and aircraft, hiking and Scuba diving...
-- in coastal and internal watersInternal watersA nation's internal waters covers all water and waterways on the landward side of the baseline from which a nation's territorial waters is defined. It includes waterways such as rivers and canals, and sometimes the water within small bays. According to the United Nations Convention on the Law of...
, surfaced submarines rely on the standard system of navigational aids (buoys, navigational markers, lighthouses, etc.), utilizing the periscopes for obtaining lines of position to plot a triangulation fix. - Voyage Management System -- referred to as the VMS, utilizes digital charts with other external sources fed in, to establish the ship's position. Other information may also be entered in manually in establishing a high quality fix or position.
Deep water navigation
At depths below periscope depth submarines determine their position using:- Dead reckoning course informationCourse (navigation)In navigation, a vehicle's course is the angle that the intended path of the vehicle makes with a fixed reference object . Typically course is measured in degrees from 0° clockwise to 360° in compass convention . Course is customarily expressed in three digits, using preliminary zeros if needed,...
obtained from the ship's gyrocompassGyrocompassA gyrocompass is a type of non-magnetic compass which bases on a fast-spinning disc and rotation of our planet to automatically find geographical direction...
, measured speedPit swordThe pit sword is a blade of metal or plastic that extends into the water beneath the hull of a nautical vessel. It is part of the pitometer log, a device for measuring the ship's speed through the water.-External links:**...
and estimates of local ocean currents, this could also be considered an estimated position as long as the ocean current is computed in. - Inertial navigation systemInertial navigation systemAn inertial navigation system is a navigation aid that uses a computer, motion sensors and rotation sensors to continuously calculate via dead reckoning the position, orientation, and velocity of a moving object without the need for external references...
-- this is an estimated position source, utilizes acceleration, deceleration, and pitch and roll in computing. - Bottom contour navigation may be used in areas where detailed hydrographicHydrographyHydrography is the measurement of the depths, the tides and currents of a body of water and establishment of the sea, river or lake bed topography and morphology. Normally and historically for the purpose of charting a body of water for the safe navigation of shipping...
data has been charted and there is adequate variation in sea floor topography. FathometerEcho soundingEcho sounding is the technique of using sound pulses directed from the surface or from a submarine vertically down to measure the distance to the bottom by means of sound waves. This information is then typically used for navigation purposes or in order to obtain depths for charting purposes...
depth measurements are compared to charted depthNautical chartA nautical chart is a graphic representation of a maritime area and adjacent coastal regions. Depending on the scale of the chart, it may show depths of water and heights of land , natural features of the seabed, details of the coastline, navigational hazards, locations of natural and man-made aids...
patterns.