Seas of Crisis

ambient noise of the surrounding ocean to catch reflections off a target. Noise sources can include surface wave- action sounds, the propulsion plants of other vessels (such as passing neutral merchant shipping), or biologics (sea life). Ambient sonar gives the advantages of actively pinging but without betraying a submarine’s own presence. Advanced signal processing algorithms and powerful onboard computers are needed to exploit ambient sonar effectively.

Auxiliary maneuvering units: Small propulsors at the bow and stern of a nuclear submarine, used to greatly enhance the vessel’s maneuverability. First ordered for the USS Jimmy Carter, the third and last of the Seawolf-class SSNs (nuclear fast-attack submarines) to be constructed.

Ceramic composite: A multilayered composite foam matrix made from ceramic and metallic ingredients. Alumina casing, an extremely strong submarine hull material significantly less dense than steel, was declassified by the U.S. Navy after the Cold War.

ELF: Extremely Low Frequency. Radio capable of penetrating deep seawater, used to communicate (one-way only) from a huge shore transmitter installation to submerged submarines. A disadvantage is ELF’s very slow data rate, only a few bits per minute.

EMCON: Emissions Control. Radio silence. Also applies to radar, sonar, or other emissions that could reveal a vessel’s presence.

EMP: Electromagnetic pulse. A sudden, strong electrical current induced by a nuclear explosion. This will destroy unshielded electrical and electronic equipment and also temporarily ruin radio reception. There are two forms of EMP, one caused by very-high-altitude nuclear explosions (“HANEs”), the other by ones at low altitude. (Mid-altitude bursts do not create an EMP.) The area on the ground affected by an EMP is called the “pancake.” EMPs in outer space (“exoatmospheric” EMPs) will also cause damage to unhardened satellites in orbit.

Frequency-agile: A means of avoiding enemy interception and jamming, by very rapidly varying the frequency used by a transmitter and receiver. May apply to radio, or to underwater acoustic communications (see gertrude below).

Gertrude: Underwater telephone. Original systems simply transmitted voice directly with the aid of transducers (active sonar emitters, i.e., underwater loudspeakers), and were notorious for short range and poor intelligibility. Modern undersea acoustic communication systems translate the message into digital high- frequency active sonar pulses, which can be frequency-agile for security (see above). Data rates well over 1,000 bits per second, over ranges up to thirty nautical miles, can be achieved.

Hole-in-ocean sonar: A form of passive (listening-only) sonar that detects a target by how it blocks ambient ocean sounds from further off. In effect, hole-in-ocean sonar uses an enemy submarine’s own quieting against it.

Instant ranging: A capability of the new wide-aperture array sonar systems (see below). Because each wide-aperture array is mounted rigidly along one side of the submarine’s hull, sophisticated signal processing can be performed to “focus” the hydrophones at different ranges from the ship. The target needs to lie somewhere on the beam of the ship (i.e., to either side).

Kampfschwimmer: German Navy “frogman” combat swimmers. The equivalent of U.S. Navy SEALs and the Royal Navy’s Special Boat Squadron commandos. (In the German language, the word Kampfschwimmer is both singular and plural.)

LASH: Littoral Airborne Sensor Hyperspectral. A new antisubmarine warfare search-and- detection technique, usually deployed from aircraft. LASH utilizes the back-scatter of underwater illumination from sunlight, caught via special optical sensors and processed by classified computer software, to locate anomalous color gradations and shapes, even through deep seawater that is murky or dirty.

LIDAR: Light Direction And Ranging. Like radar, but uses laser beams instead of radio waves. Undersea LIDAR uses blue-green lasers, because that color penetrates seawater to the greatest distance.

Multimission platform: A special extra one-hundred-foot-long, three-thousand-ton hull section added to USS Jimmy Carter, the last of the three Seawolf-class nuclear-powered fast-attack subs to be built, commissioned into the U.S. Navy in early 2005. By limiting the pressure-hull diameter within the central portion of the multimission platform to eighteen feet (the “wasp waist”), additional volume for larger weapons, off-board vehicles, and underwater fiber- optic cable tapping equipment was created between the wasp waist and the outer hull, called the “garage space.” The full-width (forty-two-foot outside diameter) sections at both ends of the multimission platform include areas for special operations command, control, and communications, and for special operations forces berthing — nominally fifty commandos, though more can be accommodated in an emergency. Reportedly, this extra hundred feet of “wetted area” of the outer hull reduces Carter’s maximum speed while submerged by less than one knot.

Naval Submarine League (NSL): A professional association for submariners and submarine supporters. See their Web site, www.navalsubleague.com.

Network-centric warfare: A new approach to warfighting in which all formations and commanders share a common tactical and strategic picture through real-time digital data links. Every platform or node, such as a ship, aircraft, submarine, Marine Corps or Army squad, or SEAL team, gathers and shares information on friendly and enemy locations and movements. Weapons, such as a cruise missile, might be fired by one platform, and redirected in flight toward a fleeting target of opportunity by another platform, using information relayed by yet other platforms — including unmanned reconnaissance drones. Network-centric warfare promises to revolutionize command, control, communications, and intelligence, and greatly leverage the combat power of all friendly units while minimizing collateral damage.

Ocean rover: Any one of a number of designs, either civilian or military, of a small, semiautonomous unmanned submersible vehicle that roves through the ocean collecting data on natural and man- made phenomena. This data is periodically downloaded via radio when the ocean rover comes shallow enough to raise an antenna above the sea surface. Ocean rovers can also be controlled and downloaded via fiber-optic tether from a submerged submarine, for greater stealth. Powered by batteries or fuel cells, ocean rovers move slowly but can have endurance of days or weeks before needing to be recovered for maintenance, reprogramming, refueling, etc. One U.S. Navy ocean rover is the Seahorse series, shaped like a very long, very wide torpedo.

Photonics mast: The modern replacement for the traditional optical periscope. One of the first was installed in USS Virginia (see below). The photonics mast uses electronic imaging sensors, sends the data via thin electrical or fiber-optic cables, and displays the output on large high- definition TV screens in the control room. The photonics mast is “non-hull-penetrating,” an important advantage over older scopes with their long, straight, thick tubes that must be able to move up and down and rotate.

Pump-jet: A main propulsor for nuclear submarines that replaces the traditional screw propeller. A pump-jet is a system of stator and rotor turbine blades within a cowling. (The rotors are turned by the main propulsion shaft, the same way the screw propeller’s shaft would be turned.) Good pump-jet designs are quieter and more efficient than screw propellers, producing less cavitation noise and less wake turbulence.

SERT: Seabee Engineer Reconnaissance Team. A modern breed of special operations forces “shadow warrior” drawn from among U.S. Navy Seabee (mobile construction) combat battalions. SERT teams, generally of ten specially trained men each, operate at the forward edge of the battle area, sometimes attached to Marine Corps formations. They use their special expertise to assess, in a warfighting environment, civil engineering requirements for tasks such as road-laying, bridge repair, and restoration of damaged or sabotaged structures and heavy machinery including power plants and waterworks. Their reconnaissance reports are relayed in real time to higher headquarters via digital network-centric warfare techniques (see above), for optimal rapid exploitation by follow-on mainline battle formations, aid relief workers, and democracy-building planners. Commissioned officers in Seabee units are members of the Navy’s Civil Engineer Corps.

Sonobuoy: A small active (“pinging”) or passive (listening-only) sonar detector, usually dropped in patterns (clusters) from an aircraft or a helicopter. The sonobuoys transmit their data to the aircraft by a radio link. The aircraft might have onboard equipment to analyze this data, or it might relay the data to a surface warship for detailed analysis. (The aircraft will also carry torpedoes or depth charges, to be able to attack any enemy submarines that its sonobuoys detect.) Some types of sonobuoy are able to operate down to a depth of