Voyage of the Devilfish

JAM DIVE An emergency that results from either the sternplanes or fairwater planes failing in the dive position, forcing the submarine toward crush depth. A highspeed sternplane jam dive is the classic accident taught at Submarine School in the diving simulators. Immediate actions include reversing the screw to All Back Full and emergency blowing to the surface. Only one in five simulations results in recovery of depth control most students are blasted down to crush depth no matter what they do.

JOOD (JUNIOR OFFICER OF THE DECK) Assistant to the OOD. When in transit, the JOOD is usually an unqualified officer in a training position, given the Conn and supervised by the OOD. When in a tactical situation, the JOOD is a senior qualified officer who shares the firecontrol duties with the OOD and is generally responsible for the firecontrol solution and release of weapons.

KEEL In the old days of sail, the keel was the plank that the ribs of the ship ere attached to, forming the backbone of the hull. Cylindrical submarine hulls do not have a physical keel. The keel is by definition the lowest point of the hull.

KH-17 Newest generation of Bigbird spy satellites. The KH stand for Keyhole — appropriate for a spy platform.

LAMINAR FLOW Smooth, layerlike, near frictionless flow over an object.

LATCH RODS The order to increase the voltage of the electromagnets on the control rod drive mechanisms to engage the motors to the rods after a scram or shut down.

LATCH VOLTAGE The increased voltage applied to the control rod drive mechanisms in order to latch rods.

LD-50 The radiation dose that will statistically kill 50 % of a population exposed. About 500 rem.

LEFT-TO RIGHT TAG REVERSAL The result of a torpedo in passive search mode doing rudder wiggle. If the target moves left and right, the target is confirmed as valid. Much like a dog cocks its head when it hears prey.

LEG The straight line travel of a submarine doing passive sonar Target Motion Analysis (TMA) between maneuvers. During a leg the crew attempts to establish a steady bearing rate to the target and establish speed across the line-of-sight to the target. Two legs determine a firecontrol solution. Three legs confirm the solution.

LINE-OF-SIGHT (1) The line from own ship to the target ship. (2) A mode of the firecontrol system used in Tape Mode and during a Snapshot. The display shows own ship as a rowboat, the target ship as another rowboat at the end of the line-of sight. The operator matches the target bearing and the bearing rate to get a crude firing solution. (3) A description of the travel of UHF radio waves, which travel in straight lines.

LIQUID METAL COOLANT Use of liquid metal as reactor coolant instead of pressurized water. Sodium and barium are two popular coolants. Abandoned by the U.S. Navy due to the dangers of a sodium-water reaction.

LIST Tilt of a ship to the side.

LITHIUM BROMIDE AIR CONDITIONER One of the air conditioners onboard that uses the absorptive method of heat transfer.

LOCKING IN/LOCKING OUT Entering or leaving a submerged submarine through the escape trunk (airlock).

LOFAR Low frequency analyzer used to determine number of screw blades on a contact’s screw.

LOOKAROUND (1) A periscope observation. (2) A warning by the OOD or captain to the ship control team that the periscope is about to be raised. The Diving Officer and helmsman report ship’s speed and depth as a reminder, since high speeds can rip the periscope off and flood the ship through the periscope hole.

LOOKDOWN-SHOOTDOWN RADAR A radar capable of seeing down into the radar grass for the purpose of destroying low flying objects.

LOOP (1) A set of piping in the primary coolant system. (2) The VLF antenna.

LOS ANGELES CLASS The class of submarines built after the last Piranha class. Faster but limited in depth. Hold more weapons and run quieter. Disadvantaged by inability to go under the polar icecap. Also less survivable than the venerated Piranhas due to the reduction of compartments from 5 to 2.

LOSS-OF-COOLANT ACCIDENT Nuclear accident caused by pipe rupture or system failure such that coolant is lost, leading to extreme temperature excursions and probable reactor meltdown. Three Mile Island was a loss-of-coolant accident.

LOW PRESSURE CUTBACK A cutback due to low pressure in the core. A protection against oncoming loss-of-coolant accident or loss-of-pressure accident.

LOW PRESSURE CUTOUT SWITCH A switch that alters reactor scram trip setpoints based on the current operation of the system.

LOW-PRESSURE TURBINE A turbine that accepts low-pressure steam from the high-pressure turbine and extracts energy from the steam for mechanical work.

MAD (MAGNETIC ANOMALY DETECTOR) A detector flown on an aircraft that measures changes in the earth’s magnetic field that could be caused by the iron hull of a submarine.