Submarine navigation

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 rigs 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;^[1] 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.

USS San Francisco (SSN-711) suffered substantial damage after colliding at high-speed with an undersea mountain.

A submarine at periscope depth risks visual or radar detection

Submarines can raise various antenna masts, radar masts and periscopes to facilitate communications and navigation

Navigational technologies

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 system (GPS) — by entering waypoints internally, able to navigate at a more precise level.
  • NAVSAT
• Terrestrial radio-based navigation systems; largely superseded by satellite systems
  • LORAN—seldom if rarely used anymore.
  • CHAYKA, the Russian counterpart of LORAN
  • OMEGA, the Western counterpart of the Alpha Navigation System, no longer in use
  • Alpha, the Russian counterpart of the Omega Navigation System
• Celestial navigation using the periscope, or sextant—seldom used anymore due to advancement in technology
• Radar navigation; 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.
• Pilotage — in coastal and internal waters, 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 information obtained from the ship's gyrocompass, measured speed 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 system is an estimated position source, utilizing acceleration, deceleration, and pitch and roll for computing.
• Bottom contour navigation may be used in areas where detailed hydrographic data has been charted and there is adequate variation in sea floor topography.^[2][3][4] Fathometer depth measurements are compared to charted depth patterns.

See also

• Bearing (navigation)
• Passive sonar
• Underwater navigation by divers

Footnotes

1. ↑ Bivens, Arthur Clarke (July 2004). From Sailboats to Submarines. Infinity Publishing. p. 184. ISBN 978-0-7414-2152-4. 
2. ↑ "Lesson 14: Electronic Navigation". Navigation and Operations I. University of Kansas, Naval Reserve Officer Training Corps. pp. Slides 19 to 21. Archived from the original (Microsoft PowerPoint) on September 11, 2006. Retrieved 2007-11-14. 
3. ↑ "2003 CJCS Master Positioning, Navigation, And Timing Plan" (PDF). Joint Chiefs of Staff. p. F-12. Retrieved 2007-11-14. 
4. ↑ S. E., Hamn (August 1995). "Coastal piloting: bottom contour navigation.(Seamanship)". Trailer Boats. Retrieved 2007-11-14. 

References

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• Craven, John Piña. The Silent War: The Cold War Battle Beneath the Sea. New York, New York: Simon & Schuster. ISBN 978-0-684-87213-1. 
• DiMercurio, Michael; Michael Benson. Complete Idiot's Guide to Submarines. Indianapolis, Indiana: Alpha Books. ISBN 978-0-02-864471-4. 
• Harris, Brayton. Navy Times Book of Submarines (1st ed.). New York, New York: Berkley Hardcover. ISBN 978-0-425-15777-0. 
• Hutchinson, Robert. Jane's Submarines: War Beneath the Waves from 1776 to the Present Day. HarperCollins Publishers. ISBN 978-0-06-081900-2. 
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• Miller, David. Modern Submarine Warefare (1st ed.). Crescent. ISBN 978-0-517-64647-2. 
• Parrish, Tom. The Submarine: A History. New York, New York: Viking Penguin. ISBN 978-0-670-03313-3. 
• Preston, Antony (1999). Submarine Warfare: An Illustrated History. San Diego, California: Thunder Bay Press. ISBN 978-1-57145-172-9. 
• van der Vat, Dan. Stealth at Sea: The History of the Submarine. Houghton Mifflin. ISBN 978-0-395-65242-8. 
• Waller, Douglas C. Big Red: Three Months on Board a Trident Nuclear Submarine. HarperCollins Publishers. ISBN 978-0-06-019484-0.