Voyage of the Devilfish

GUIDANCE WIRE A neutrally buoyant wire streamed from the rear of a Mark 49 or 50 torpedo allowing communication between the weapon and the firecontrol system. Used to pass steer commands from ship to torpedo and information about the target from torpedo to ship, GYRO/GYROSCOPE Electrical compass using a rapidly spinning gyroscope.

HAFNIUM Element used in Navy control rods. Acts as a black hole for neutrons. Without neutrons, fission reactions stop, and a core is shutdown.

HALF POWER LINEUP Electric plant lineup when the reactor is critical and self-sustaining. One turbine generator is at 3600 RPM and supplying power to the ship’s loads. The battery is not discharging.

HARD RUDDER A rudder angle of about 37 degrees. An emergency order because it risks being unable to return the rudder to an amidships position.

HARDENED SAIL A sail constructed of 3 inch thick HY-80 steel designed to break through polar ice.

HEAVY WATER Deuterium. Used in nuclear fusion reactors or fusion (hydrogen) bombs.

HELM The wheel that turns the ship’s rudder. Also short for helmsman.

HF (HIGH FREQUENCY) Radio waves capable of reception continents away. Reception is often unreliable, susceptible to various atmospheric conditions.

HOMING A torpedo in the final stages of arming and pursuit of a target.

HOT RUN A serious emergency resulting from a torpedo that starts its engine while still in the tube or in the torpedo room. Hazards include the toxic gas exhaust and probability of warhead detonation.

HOT STANDBY A condition of a shutdown reactor and steam plant such that the systems are kept as warm as possible to allow a more rapid startup.

HOVERING SYSTEM A depth control system managed by a computer that keeps the ship in one point underwater. Used by boomers when launching missiles. Used by fast attack submarines to establish a desired vertical speed (depth rate) to vertical surface through polar ice.

HULL ARRAY One of the sonar hydrophone element assemblies (arrays) of the BAT-EARS sonar suite, consisting of multiple hydrophones placed against the skin of the hull over about 1/3 of the ship’s length. Used mostly as a backup to the spherical array because the hull array’s sensitivity is reduced by own ship noise inside the hull.

HYDRAULICS Use of oil under pressure to cause motion in large equipment. Used to move the planes and rudder and to raise masts and antennae. In the nuclear plant, primary coolant (water) is used to move valves.

HYDRODYNAMIC FORCES Lift, downforce, or drag caused by the flow of water over the surface of a moving object.

HYDROPHONE A device that converts mechanical motion of soundwaves into electrical signals to be amplified and analyzed by the sonar system. Somewhat like a large microphone. A set of hydrophones forms an array. Hydrophones are passive devices designed for reception only. A transducer can either receive or transmit sonar pulses.

HY-80 STEEL A special alloy of steel made for the Navy. HY stand for high yield. 80 stands for yield stress of 80,000 psi. One of the strongest and toughest steels made. Used for the pressure hull plates and frames of the Piranha and Los Angeles classes.

IMMEDIATE The priority of a radio message just below FLASH. Receipt required within an hour.

IMPLOSION An inward explosion, such as a pressure hull crushed by seawater pressure.

INCLINOMETER A liquid filled tube in the shape of an upside down U with a small bubble at the top. A low-tech method to measure the angle or roll of the ship.

INDUCTION PIPING Piping from the snorkel mast to the ship for use by the diesel generator when the ship is snorkeling.

INTAKE DIFFUSER The air intake of a jet engine. A diffuser is the opposite of a nozzle. It slows down the incoming airstream and raises its pressure.

INTEGRATE The accumulation of data of the BAT-EARS narrowband sonar processors. Tonal frequencies are examined and plotted against time. The longer a tonal is heard, the more certain the computer is that the tonal is not random but is a contact.

INTERLOCK An electrical circuit or mechanical device that prevents unsafe actions. A mechanical example is the shaft that prevents opening a torpedo tube inner door when the outer door is already open, thus preventing opening a hole to the ocean. An electrical example is the reactor protection circuits scramming the reactor if the plant exceeds 103 % power to prevent a meltdown.

INTERMEDIATE RANGE A region of reactor power that is passed through on the approach to the power range. When in creasing power, the reactor is just slightly supercritical. When decreasing power after a scram, the core is subcritical. The region of neutron level between the startup range and the power range.

INVERTER An electrical device that converts DC power into a step AC current. Used to drive control rod motors.

INVERTER ALPHA The inverter normally used for the controlling rod group.