Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another. The field of navigation includes four general categories: land navigation, marine navigation, aeronautic navigation, and space navigation.
A submarine is a watercraft capable of independent operation underwater. The term “submarine” is also sometimes used historically or informally to refer to remotely operated vehicles and robots, or to medium-sized or smaller vessels. Submarines are referred to as boats rather than ships regardless of their size.
Sonar is a technique that uses sound propagation to navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels.
A buoy is a floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents.
The Gato class of submarines were built for the United States Navy and launched in 1941–1943. Named after the lead ship of the class, USS Gato, they were the first mass-production U.S. submarine class of World War II.
A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position.
Piloting or pilotage is the process of navigating on water or in the air using fixed points of reference on the sea or on land, usually with reference to a nautical chart or aeronautical chart to obtain a fix of the position of the vessel or aircraft with respect to a desired course or location. Horizontal fixes of position from known reference points may be obtained by sight or by radar. Vertical position may be obtained by depth sounder to determine depth of the water body below a vessel or by altimeter to determine an aircraft's altitude, from which its distance above the ground can be deduced. Piloting a vessel is usually practiced close to shore or on inland waterways. Pilotage of an aircraft is practiced under visual meteorological conditions for flight.
Communication with submarines is a field within military communications that presents technical challenges and requires specialized technology. Because radio waves do not travel well through good electrical conductors like salt water, submerged submarines are cut off from radio communication with their command authorities at ordinary radio frequencies. Submarines can surface and raise an antenna above the sea level, or float a tethered buoy carrying an antenna, then use ordinary radio transmissions; however, this makes them vulnerable to detection by anti-submarine warfare forces.
Acoustic homing is the process in which a system uses the sound or acoustic signals of a target or destination to guide a moving object. There are two types of acoustic homing: passive acoustic homing and active acoustic homing. Objects using passive acoustic homing rely on detecting acoustic emissions produced by the target. Conversely, objects using active acoustic homing make use of sonar to emit a signal and detect its reflection off the target. The signal detected is then processed by the system to determine the proper response for the object. Acoustic homing is useful for applications where other forms of navigation and tracking can be ineffective. It is commonly used in environments where radio or GPS signals can not be detected, such as underwater.
A sonobuoy is a small expendable sonar buoy dropped from aircraft or ships for anti-submarine warfare or underwater acoustic research. Sonobuoys are typically around 13 cm (5 in) in diameter and 91 cm (3 ft) long. When floating on the water, sonobuoys have both a radio transmitter above the surface and hydrophone sensors underwater.
An anti-submarine weapon (ASW) is any one of a number of devices that are intended to act against a submarine and its crew, to destroy (sink) the vessel or reduce its capability as a weapon of war. In its simplest sense, an anti-submarine weapon is usually a projectile, missile or bomb that is optimized to destroy submarines.
Anti-submarine warfare is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are typically carried out to protect friendly shipping and coastal facilities from submarine attacks and to overcome blockades.
The history of the submarine goes back to antiquity. Humanity has employed a variety of methods to travel underwater for exploration, recreation, research and significantly, warfare. While early attempts, such as those by Alexander the Great, were rudimentary, the advent of new propulsion systems, fuels, and sonar, propelled an increase in submarine technology. The introduction of the diesel engine, then the nuclear submarine, saw great expansion in submarine use — and specifically military use — during World War I, World War II, and the Cold War. The Second World War use of the U-Boat by the Kriegsmarine against the Royal Navy and commercial shipping, and the Cold War's use of submarines by the United States and Russia, helped solidify the submarine's place in popular culture. The latter conflicts also saw an increasing role for the military submarine as a tool of subterfuge, hidden warfare, and nuclear deterrent. The military use of submarines continues to this day, predominantly by North Korea, China, the United States and Russia.
A submarine snorkel is a device which allows the engine of a submarine to operate submerged while still taking in air from above the surface. British Royal Navy personnel often refer to it as the snort. A concept devised by Dutch engineers, it was widely used on German U-boats during the last year of World War II and known to them as a schnorchel.
Geophysical MASINT is a branch of Measurement and Signature Intelligence (MASINT) that involves phenomena transmitted through the earth and manmade structures including emitted or reflected sounds, pressure waves, vibrations, and magnetic field or ionosphere disturbances.
Guidance, navigation and control is a branch of engineering dealing with the design of systems to control the movement of vehicles, especially, automobiles, ships, aircraft, and spacecraft. In many cases these functions can be performed by trained humans. However, because of the speed of, for example, a rocket's dynamics, human reaction time is too slow to control this movement. Therefore, systems—now almost exclusively digital electronic—are used for such control. Even in cases where humans can perform these functions, it is often the case that GNC systems provide benefits such as alleviating operator work load, smoothing turbulence, fuel savings, etc. In addition, sophisticated applications of GNC enable automatic or remote control.
An underwater acoustic positioning system is a system for the tracking and navigation of underwater vehicles or divers by means of acoustic distance and/or direction measurements, and subsequent position triangulation. Underwater acoustic positioning systems are commonly used in a wide variety of underwater work, including oil and gas exploration, ocean sciences, salvage operations, marine archaeology, law enforcement and military activities.
A short baseline (SBL) acoustic positioning system is one of three broad classes of underwater acoustic positioning systems that are used to track underwater vehicles and divers. The other two classes are ultra short baseline systems (USBL) and long baseline systems (LBL). Like USBL systems, SBL systems do not require any seafloor mounted transponders or equipment and are thus suitable for tracking underwater targets from boats or ships that are either anchored or under way. However, unlike USBL systems, which offer a fixed accuracy, SBL positioning accuracy improves with transducer spacing. Thus, where space permits, such as when operating from larger vessels or a dock, the SBL system can achieve a precision and position robustness that is similar to that of sea floor mounted LBL systems, making the system suitable for high-accuracy survey work. When operating from a smaller vessel where transducer spacing is limited, the SBL system will exhibit reduced precision.
A long baseline (LBL) acoustic positioning system is one of three broad classes of underwater acoustic positioning systems that are used to track underwater vehicles and divers. The other two classes are ultra short baseline systems (USBL) and short baseline systems (SBL). LBL systems are unique in that they use networks of sea-floor mounted baseline transponders as reference points for navigation. These are generally deployed around the perimeter of a work site. The LBL technique results in very high positioning accuracy and position stability that is independent of water depth. It is generally better than 1-meter and can reach a few centimeters accuracy. LBL systems are generally employed for precision underwater survey work where the accuracy or position stability of ship-based positioning systems does not suffice.
German submarine U-1308 was the last Type VIIC/41 submarine to be laid down, launched and commissioned by Nazi Germany's Kriegsmarine during World War II. The Oberkommando der Marine or OKM,, had decided near the end of World War II to put all of its resources into building newer types of Unterseeboot, such as the types XXI and XXIII. U-1308 was part of a batch of eight U-boats ordered on 1 August 1942 to be built at Flensburger Schiffbau-Gesellschaft, Flensburg. She was laid down on 16 February 1944 and launched on 22 November. The eight boats were commissioned over a 12-month period between February 1944 and 17 January 1945.
