(Last Updated December 28, 2016: Added, "Torpedo Advanced Propulsion System")

Anchor: tbd

Anchors Aweigh: The original 1906 unofficial theme song of the United States Navy (Wikipedia), composed by Charles A. Zimmerman. The song has been revised over the years.

The term "anchors aweigh" is more applicable to surface ships than submarines, where it has a definite meaning of raising the anchor. It is equivalent to declaring, on the Halibut, "Captain, Halibut is underway", meaning the last mooring line has been removed and the nuclear reactor (Westinghouse SG3) is providing Halibut's propulsion.

On the Halibut it was quite common to have "anchor pools" where players contributed a small sum of money (usually $5 or $10) to a pot. The contribution entitled you to select a grid square which corresponded to a definite time, but which was not revealed until after the quartermaster logged the official "docking time". The time closest to the official time won the pot of money.

Some "anchor pools" where for considerably larger sums of money, but these where always "discretely" run - like a 1920s prohibition operation you had to be in the know to participate - these large sum "anchor pools" were "discouraged".

The navy's theme song was regularly played during Halibut's ceremonies and formal events.

Anchors, Mushroom: Halibut had two large mushroom anchors (the anchors look like upside down mushrooms) which it used to anchor over a seabed target, winch itself onto the seabed, and secure itself to the seabed.

Sea currents, sea turbulence, submarine atmosphere, and equipment malfunctions, made getting to the seabed and staying there challenging.

If the stresses and loads on the anchor or cable caused an anchor to separate from the submarine, as sometimes happened, Halibut headed home for repairs and extensive failure analysis.

Anchoring is primarily a function of the anchor's ability to "penetrate" the seabed and the seabed's ability to "hold" the anchor once penetrated.

Seabed "penetration" and "holding" is primarily a function of anchor size, shape and weight, given seabed composition and sea characteristics.

A mushroom shaped anchor is used when the seabed is primarily muddy. The weight of the mushroom anchor determines the degree to which it penetrates the muddy seabed. The goal is a fully buried mushroom anchor because its "holding" properties are the greatest (more than 5 times greater for a given anchor size and weight).

Question: Like getting your shoe and foot buried up to your ankle in mud - the "suction" of the mud makes it very hard to lift your foot. The mud may even "hold" your shoe after you are able to free your foot from the mud. Because of the size, shape, and surface area of a mushroom anchor the mud "holds" it much stronger than your shoe and foot. If you are in high school see if you can calculate the surface area and weight of half a steel, iron, or lead sphere 7 feet in diameter. Assume a cubic foot of each metal weighs 487, 480, and 710 lbs, respectively. If a mushroom anchor that is completely buried in mud can "hold" 5 times its weight what is the effective "holding" tonnage for each (steel, iron, and lead) mushroom anchor? Would your answers change if each mushroom anchor was not solid, but partially hollow?

Question: Early Halibut operations anchored, but did not winch down onto the seabed. Why would Halibut change to winching onto and sitting on the seabed? If the “holding” property of the mushroom anchor is greater than the "cable strength" attached to the anchor what happens to the cable when Halibut tries to winch in the anchor? When Halibut was anchored over a target was submarine buoyancy negative, neutral, or positive? When Halibut was winching down toward the seabed was submarine buoyancy negative, neutral, or positive? When Halibut was sitting on the seabed, with her mushroom anchors buried in the muddy seabed was submarine buoyancy negative, neutral, or positive?

Question: When Halibut deanchored from the seabed was submarine buoyancy negative, neutral, or positive?

Anchoring Operation, Halibut: Anchoring Operation

Antenna, AN/BRA-34: A primary mast antenna used for communications and navigation (satellite GPS)—replaced by the newer universal modular mast (UMM) OE-538/BRC.

The OE-538/BRC can receive (Rx) over the broad spectrum of very low frequency (VLF) to ultra high frequency (UHF). It can transmit (Tx) over high frequency (HF) to ultra high frequency (UHF), including very high frequencies (VHF) used by special forces.

The OE-538/BRC incorporates identification friend or foe (IFF) and demand assigned multiple access (DAMA) both critical for effective network centric warfare.
See also Spectrum, Submarine Communications for definition for range of category frequencies (ELF, VLF, HF etc.)

Antenna, HDR (OE-562/BRC): High Data Rate (HDR) submarine antenna is a pizza size (16" dish antenna covered by a dome. It provides high data rate (HDR) satellite communication at extremely high and super high frequencies.
It also supports the Global Broadcast Service (GBS) enabling the submarine to access military network and Internet digital data.

The HDR antenna is a key component in the Navy's evolving vision of ubiquitous network centric platform communications. The Phased Array Antenna may eventually replace the HDR antenna.

See Wikipedia, Joint Electronics Type Designation System for explanation of electronic equipment and component naming nomenclature (e.g. OE-562/BRC).

Aquarium, Halibut: This is a nickname given to the sea-lock, located in the lower hangar, used to transfer hardware through Halibut's pressure hull while at sea. The sea-lock had a diameter of about 46 inches and consisted of three hatches, an inner, middle, and outer. Most often the transferred hardware consisted of towed search vehicles, remotely operated vehicles, signal recording pods, and items recovered or requested by deployed divers.

Anchor Pool: see Anchors Aweigh.

Anechoic Tiles or Coating: Tiles or coating applied to a submarine's outer hull which aids in sound absorption, echo distortion, and improved hydrodynamics, attributes enhancing a submarine's stealth characteristics.

Artificial Sea Water: This is "designer water" intended to simulate the chemical composition of a particular ocean's environment, generally used in controlled simulation and testing. Salt is one significant component of most seawater. Sometimes this is referred to as ocean, salinity, but salinity refers to more than salt. a typical salinity can range from 30 to 37 grams per kilogram of seawater. Salinity - Sea of Okhotsk and hydro chemical atlas - sea of Okhotsk

Other seawater chemicals are: chlorine,Cl; sodium, Na;magnesium, Mg; sulphur, S; calcium, Ca; potassium, K; bromine, Br; carbon, C; nitrogen, N; strontium, Sr 8; oxygen, O; boron, B; silicon, Si; fluorine, F; argon, Ar; lithium, Li; rubidium, Rb; phosphorus, P; ... for a complete list see: Ocean Chemistry and Deep Sea Sediments

Can you think how this salt might affect the submarine's buoyancy? (hint: Does the density of the water increase or decrease when you add salt? Assume sea water has an average specific gravity of 1.0218).

Scenario: You are officer of the deck supervising the diving office's manual control of the submarine's depth. The submarine sensors indicate you are about to enter an area of increased salinity (see thermohaline ). Would you tell the chief of the watch (cow) to pump water out of, or into the submarine, why?

Question: Assume the cow tells you the water pump just blew out! While listening to the cow immediately call the "on watch" electrician mate, could you direct the diving officer to increase/decrease the submarine's speed and achieve the same result as pumping water into or out of the submarine?increase/decrease/why?

Question: Do factors such as ocean temperature, ocean currents, ocean bathymetry (depth) [Sea of Okhotsk bathymetry], submarine hydrodynamics, ocean storms, and rainfall affect sea water composition and thus submarine performance? Why or Why not?

Question: If you are a submarine designer, why is sensing and responding to changes in the submarine's hydro chemical environment so important?

Atmosphere Independent Propulsion: tbd


Ballast: A submarine is designed with significant positive buoyancy margins. Weight, in the form of "lead bricks", is added to attain estimated deployment buoyancy. These lead bricks are called ballast and are usually attached to the hull inside the ballast tanks (there are generally three types of ballast, margin, permanent, and variable).

Ever wonder how much all the food consumed by Halibut's crew during a 110 day deployment weighs? How much all the spare parts weigh? How much all the oxygen candles weigh? How much the crew weighs? What is the variance between Halibut's pre and post deployment weight?

If you were the engineer responsible for Halibut's ballast you would wonder about all these things and a lot more!

Where you place the lead ballast matters, why (hint: think in terms of the submarine's centers of gravity and buoyancy)? Ballast place inside a main ballast tank decreases the volume of that ballast tank in addition to adding weight to the submarine. If you are in high school convince yourself that both the submarine's center of gravity and center of buoyancy are effected?

Does ballast have to be lead bricks? What would happen if the added ballast is less dense than lead? sea water? air? When you "blow the ballast tanks" can that be considered adding "air ballast" (permanent,margin or variable?), which is considerably less dense than the sea water it replaces? What would happen if you were on a weird submarine that "blows the ballast tanks" with milk instead of air?

Ballast Tanks: see Tanks, Ballast.

Basketball: A basketball size, remotely operated under water vehicle containing a camera. The basketball was primarily used to obtain "inspection pictures" while Halibut was "on the seabed". These pictures were sent to Halibut's display room where the rov operator stood watch. Because, the rov could simultaneously vector in three planes it required considerable skill to effectively operate - like learning to neatly write your name on paper using only a mirror.

Beam: The wide of a submarine at its widest point. Halibut's beam was 29 feet.

Bilge(s): A submarine is essentially a large pipe containing other pipes, electrical cabling, machinery, weaponry, and sailors.

The leakage from the piping and machinery has to go somewhere and most of it goes to the bilges running along the keel of the submarine like a polluted and contaminated stream.

Three major contributors to the stream are seawater, condensate, and hydraulic fluids. All mixing into a gooey mess. A major source of seawater leakage is the submarine's seals which are a sort of rubber inner tube around the propeller shaft(s). The condensate formed as a result of the warm air inside the submarine coming into contact with the very cold steel hull (check out the temperatures of the Sea of Okhotsk in the winter!). Hydraulic fluids are constantly flowing throughout a submarine doing various work like moving control planes, opening and closing valves, and lubricating machinery.

Certain Halibut bunks (beds) had huge hydraulic values above them. The unfortunate sailor getting assigned one of these bunks quickly jerry rigged a plastic liner between the valve and his bunk to prevent the hydraulic fluid from leaking on him or his bunk. He also got use to the loud (when your trying to sleep) sound of gushing hydraulic fluid every time somebody decide to cycle that value.

Pumping (to the ocean) and cleaning the bilges was not a job most Halibut sailors lined up to perform. In fact cleaning bilges was considered a sort of punishment by most, except for the machinists whose job pretty much required living in and around bilges when they weren’t playing poker (I mean cards:) or sleeping.

Bow Planes: tbd

Bridge Fin: see Sail

Buoyancy, Law of: If a submarine's total weight is less than the total weight of the water it displaces, that submarine will float in that water. It is said the submarine exhibits positive buoyancy or that it is surfacing. Likewise if a submarine's total weight is more than the total weight of the water it displaces, that submarine will sink in that water. It is said the submarine exhibits negative buoyancy or that it is submerging or diving. Finally, if a submarine's total weight is equal to the total weight of the water it displaces, that submarine will neither sink nor float in that water. It is said the submarine exhibits neutral buoyancy or that it is hovering.

It's hard to improve on this old newsreel from the Bureau of Aeronautics:

Those wanting to demonstrate these principles to their (grand) children can conduct some simple experiments with them.

Young: Use an empty soda bottle in a volume of water, say a pool or bathtub. Tell them that the liter soda bottle represents a submarine full of men, equipment, food and its ballast tanks full of air. Now place the bottle on the water and show that it floats, positive buoyancy. Tell them if the bottle is to submerge it must add more weight, in this case your hand applying downward force and explain that this is like a submarine filling its ballast tanks with water.

Teenage: Use the same example but add some numbers to your explanation. The plastic soda bottle filled with air (primarily nitrogen and oxygen) weighs approximately 1 gram and the weight of the water which this same plastic soda bottle displaces is approximately 1000 grams! Since 1 gram is less than 1000 grams the bottle floats or exhibits positive buoyancy. If the children can actually measure the weight of the bottle and water it will be more meaningful.

Teenage(Adv):Use a glass cylinder, placing a chunk of dry ice (carbon dioxide) at the bottom of the cylinder. Blow some bubbles (you can use the same stuff children do or make your own mixture) over the cylinder so they float down into the glass cylinder. As the bubbles, full of air, float down into the glass cylinder they exhibit negative buoyancy. When the bubbles enter the cylinder they will begin to slow, hover, and increase in size before sinking again to the bottom of the cylinder. The bubble is heavier than the air (nitrogen is 28 atomic mass units and oxygen is 32 atomic mass units) which it displaces so it sinks (negative buoyancy). When the bubble enters the glass cylinder it encounters a different environment (as submarines routinely do) composed of CO2 gas (carbon dioxide has an atomic mass unit of 44) which is denser than air. In this dense CO2 environment the bubbles initially displace more weight than it did in air so it hovers. Eventually, the bubbles fill with CO2 (the air inside the bubble is displaced by CO2) and begin to sink. The bubbles now weigh more than the CO2 which it displaces.


Cable, Anchor: tbd

Cable, Towed Vehicle (aka Fish): tbd

Cable, Sea of Okhotsk Communications: The under sea communications cable from the Kamchatka Peninsula to Vladivostok ( speculative map of communication cable). The cable connects Moscow, via Vladivostok, with the ballistic missile submarine base at Rybachy, in the Avacha Bay, across from Petropavlovsk-Kamchatsky, on the south-east side of the Kamchatka Peninsula.

Carbon Dioxide Scrubber (COScrubber): Each submariner will respire approximately 2.3 pounds of CO2 gas per day or .095 pounds per hour.

If a submarine holds 130 submariners then a total of 12.45 pounds of CO2 is respired each hour. Unless this  CO2  is removed from a submerged submarine's atmosphere it soon interferes with the red blood cells' ability to deliver oxygen to the body's cells and the submariners quickly suffocate (how soon?).

The COscrubber mixes a solvent, usually monoethanolamine (MEA) with the submarine's atmosphere, which contains the CO2. The MEA binds with the CO2 and then undergoes a cool-hot cycle that strips off the CO2 from the MEA. The isolated CO2 is then pumped overboard. The "clean" MEA is returned to system where it rebinds with additional COand the cycle repeats.

Existing submarine COscrubbers can remove approximately 12 pounds of  COper hour from the atmosphere—fortunately about a forth of the submarine crew is sleeping or relaxing at any given time (why?)!

Future COscrubbers will be capable of  removing approximately 20 pounds COper hour from a submerged submarine's atmosphere. The MEA solvent will be replaced by a solid sorbent that uses a similar cool-hot absorption-desorption cycle.

Cavitation: tbd

Center of Buoyancy, Submarine: For a good non-mathematical online introductory discussion of Center of Buoyancy, Center of Gravity, and Metacenter see San Francisco Maritime National Park Association, The Fleet Type Submarine Online, Chapter 5

Center of Gravity, Submarine: See also Center of Buoyancy

Chief of the Boat (COB): Generally, but not always is the most senior enlisted person permanently assigned to a submarine.

The COB routinely interacts with all the submarine's crew and Executive Officer on all types of issues relating to the effective and efficient operations of the submarine.

The submarine's COB is a senior or master chief petty officer and will usually have spent his entire careers aboard submarines if not a couple in a single class.

A COB knows submariners and a submarine including the submarine he's running; knows how to get things done; and reads the "rule book" with a certain amount of flexibility and bias for the enlisted submariners he manages and represents.

It’s not unusual for a submarine to have small groups temporarily or permanently assigned to a submarine sometimes with their own leadership structure. If the group is enlisted it will be subordinate to the COB and its leader will work with the COB to ensure smooth submarine operations. In some cases the COB may not even know the groups true mission (e.g. a seal or intelligence team).

Chief of the Watch (COW): This sailor, typically a senior chief petty office, performs tasks as requested, directed, and ordered by the officer of the deck. On the Halibut these tasks could include anything from tracking down an odd smell or noise; finding out why the coffee maker isn't fixed yet; getting an atmospheric sample; reporting on the submarine's water tightness, communicating with and coordinating other watch standers, deploying various antennae; pumping water around to vary the submarine's weight (trim). In short he acts as the officer of the deck's right hand man during his watch.

The COW stood his watch in the Halibut's control room.

Candle, Oxygen (O2): These are heavy metal cylinders of solid chemicals that are opened like a can of spam and burned in a special garbage can size container. When the solid chemicals are burned the reaction released oxygen into Halibut's atmosphere. Each cylinder is about the size of a fat roll of paper towels and very dense. Most, if not all, Halibut sailors dreaded loading the hundreds of "candles" taken on each mission, because they were so numerous and heavy. A completely burned oxygen candle leaves a gray ash like residue similar to the ash in a typical fireplace.

Compartment, Torpedo: tbd

Con:  Abbreviation for the area from which the Officer of the Deck watch stander directs and manages all subordinate watch standers in accordance with the captain's orders to ensure responsible execution of all submarine operations while deployed.

Control Room: An area within the Operations Compartment that places in close proximity the standard watch stations required for the submarine's effective conduct of wartime operations. These watch stations may vary from submarine to submarine or even deployment to deployment, but will usually include, as a minimum the OOD, COW, Diving and Control Surfaces, Navigation, Sonar, Weapons Control, Electronic Measures and Counter-measures.

Control Surface, Stern: See Stern Planes

Control Surface, Bow: See Bow Planes

Conversion Ratio, Neutron: The ratio of the rate of production of fissile nuclei to the rate of consumption of fissile nuclei.

The Halibut used highly enriched uranium (HEU-95), U235 for its pressurized water reactor with graphic moderators. A typical conversion ratio may range between .6 and .8, with heavy water and graphite moderators skewing toward higher CRs (Why?).

A CR of less than one implies you are burning more fissile actinides than breeding so refueling (aka re-coring) will be required, at some point.

Ideally, that point is beyond the submarine's life cycle, but as with all things submarines there are trade-offs—which makes submarines and their design interesting, even when applying a mature sciences like nucleonic.

Crashback: A submarine will periodically find itself about to crash into an object, like an undocumented sea mound, another submarine, a surface ship, the shore, the pier etc.

One possible maneuver to arrest the submarine's forward momentum and hopefully avoid the crash is to reverse the rotation of the propulsor—this is called a crashback (aka "Oh [string of expletives], all back full or flank!").

During a crashback the stresses and loads on the submarine's propulsor components increase depending on the initial forward momentum and speed of the propulsor's reverse rotations. More work is needed to completely understand these stresses and loads.

On the Halibut which had a two propeller propulsor system crashbacks where often used as a maneuvering technique (a partial crashback) as opposed to collision avoidance (although Halibut used crashbacks for crash avoidance too).

By reversing one propeller while forwarding the other and assisted by lateral bow thrusters Halibut could "turn in place", a submarine version of "spinning doughnuts"! This maneuver was particularly useful when Halibut was in target search and acquisition mode.

Crew's Mess: tbd


Dead Reckoning:

"Dead reckoning is the process of determining one’s present position by projecting course(s) and speed(s) from a known past position, and predicting a future position by projecting course(s) and speed(s) from a known present position. The DR position is only an approximate position because it does not allow for the effect of leeway, current, helmsman error, or compass error." --National Geo-spatial Agency Def. Dead Reckoning--

The etymology of dead reckoning is principally debated between an abbreviation for deduced (e.g. "ded.") position and an absolute expression (e.g. "dead right") of position calculation.

Declension: A Halibut codeword.

Displacement, Full: The submarine is loaded to its maximum design capacity, usually with everything needed to conduct its assigned operations (men, food, parts, water etc). It is sometimes said the submarine is at its draft limit.

Display Room: tbd

Diver Control, Master: tbd

Diver Controllers: tbd

Diver, Saturation: A deep depth diver whose body has been saturated in a compressed mixed gas environment to a particular depth and temperature, for a given period of time. For the Halibut, these parameters could vary between 350 - 450 feet, 0C - 6C or 32F - 43F , and 6 to 120 days (de)compression cycle (see note 1), respectively.

Typically, the four saturation divers chosen for each mission entered Halibut's saturation habitat near the submarine's deployment from either Mare Island Naval Shipyard, Vallejo, CA or Guam Naval Base in route to the Sea of Okhotsk. All dive team members focused on ensuring the habitat divers were safely "at depth" and ready to work, when Halibut anchored over its target.

A saturation diver cannot breath "normal air", which contains approximately 78% nitrogen, 21% oxygen, and 1% other gases, below 100 feet. At depths below 100 feet the pressure begins to force the nitrogen molecules (atomic weight of 14, actually 14.0067) into the diver's blood stream. When these concentrated nitrogen molecules cross the diver's blood-brain barrier the diver will become incoherent (nitrogen narcosis), and eventually pass-out.

It is not as simple as decreasing the nitrogen percentage and increasing the oxygen (atomic weight 16, actually 15.9994) percentage. High concentrations of oxygen result in oxygen poisoning, causing the diver to become dizzy, vomit and eventually convulse.

Therefore, the percentages of "normal air" are varied by increasing the amount of helium (atomic weight 4.00, actually 4.00260) and decreasing the percentages of the other gases (mostly the nitrogen concentration) for a specific temperature and depth. Helium (He), is tasteless, colorless, odorless, and responds differently than other gases to temperature and pressure. Helium remains in a gas state, even at very cold temperatures and significant pressures. It can be manufactured in different grades, "A" being the purest. (Those interested in the fascinating and complex chemistry of saturation diving should check out the reference links below.)

When saturation divers are deployed, they're always "chatty", with each other and their controller’s. This is no idle chatter though; they are "signaling" how a specific gas mixture (heliox) is affecting them, as they work.

On the Halibut all divers reported to the master diver (usually a senior chief), who reported to the captain, in coordination with the diving medical officer, trained to address the specific medical needs of saturation divers.

note: 1. The science of compression/decompression is extremely complex. The navy simplifies this complexity by providing the diver controllers (team) with predetermined schedules, to follow. (eg. diver a has been at depth x breathing y concentration of O2 for z days, so follow schedule t.) Refer to the navy's diving manual below, chapter 14, for more details on schedules.


US Navy Diving Manual Rev 6 (pdf), mixed gas diving chapters 12 - 16

Mixed gas in diving; B.R. Wienke; Applied theoretical physics division, Los Alamos National Laboratory

Physiology and physics of helium; Robert Palmer, European training director, technical diving international

The physiology of decompression illness; Richard Moon, Scientific American August 1995

Diving Officer: The person responsible for maintaining the submarine's depth, course and speed, as ordered by the officer of the deck. The diving office, typically an officer, sits between and behind the stern planes man and rudder/bow planes man. When the officer of the deck orders a depth change the diving officer will repeat the order and then direct the planes man, who repeat the order. for a course change the procedure is the same. For A speed change the planes man, on order, will typically signal maneuvering of the desired speed change who then adjust the propulsion plant (reactor) accordingly. After the signals have been acknowledged and implemented the planes man will report back to the diving officer who then reports back to the officer of the deck that the speed is as ordered. Each of these orders is routinely and smoothly implemented in a matter of seconds, unless a problem occurs in which case the problem is reported back and appropriate action taken.

The diving officer stood his watch in the Halibut's control room.

Dolphins, Submariner's: A unique insignia (see picture at top of post), silver for non-commissioned officers and gold for commissioned officers, signaling a submariner has mastered ("qualified") the minimum requirements necessary for being designated a submarine sailor.

In practical terms it meant you did not sleep until you studied and learned enough about your submarine to ensure you were not a danger to yourself or your shipmates. It also meant you could perform more duties and someone more senior than you could perform less, giving them a big incentive to ensure you "qualified" as soon as possible.

Qualification could take between three and 12 months, depending on your motivation, you’re "sea-dad's" (mentor) motivation, and your other duties. Everybody was required to "qualify" and you were not considered a member of the club until you did so. After qualification you were presented with your dolphins in a small, but "big deal" ceremony and were entitled to write "SS" (Submarine Service) after your Rank and Rate.

Doppler, Sonar: tbd

Draft Limit: The maximum number of feet, allowed by design, between the submarine's waterline and keel.


Electromagnetic Induction: tbd

Emergency Breathing Mask: tbd

Engineering Compartment: tbd


Failure Analysis: tbd

Fire Alarm: tbd

Fish: A hydro dynamically shaped fiberglass shell that housed low light cameras, high intensity lights, and side look sonar. The shell was approximately 6.5 feet in length and 3 feet in diameter, tapering to a point aft where its fins where located. The shell was not subject to differential sea pressure ( ie it freely flood with seawater) unlike the electronics it housed. The entire shell was suspended by "hot cabling" through which it sent video and sonar signals to the Halibut's display room.

A fish was usually deployed, via the aquarium, after a large area search, with Halibut's side look sonar, revealed multiple targets of interest needing further and closer examination.

A deployed fish could not navigate on its own. It was completely dependent on the Halibut's position, hydrodynamics, sea conditions, and the length of the cable between it and the Halibut at any particular time. Searching with a "fish" required a Halibut sailor to combine a lot of art with a little science. The science of precisely navigating to a fixed point over a great distance was in its infancy.

Flapper King: tbd

Flounder Diagram: Two dimentional representation of a submarine's intra-pressure-hull space, typically by function, engineering, control, mess, heads, ward room etc.

Fuel Cycle, Nuclear: tbd

Full Power Days: tbd


Galley: tbd

GDU: Garbage Disposal Unit is generally used to send netted and weighed garbage to the seabed. It functions like a small (approximately six inches in diameter) torpedo tube. It, too, can be used to launch small objects (besides netted garbage) to sea, like a transponder marking a target location.

Although on the Halibut it was used to launch transponders.


Habitat, Saturation Diver: tbd

Half-Life: The time it takes a quantity of atom in a radioactive substance to decay by half.

A submarine reactor contains a variety of decaying radioactive substances referred to as radionuclides. Each radionuclide has a known half-life and decay chain.

Because all radiation present risks to living organism (e.g. humans) they must be protected from a radionuclide's decay chain emitting energies (i.e. alpha, beta, gamma, and x-ray energy) until the radionuclide's half-life approximates zero.

Considerable costs and efforts are required to ensure humans are protected from this radioactive waste over some extremely long periods. (See the Environmental Protection Agency (EPA), Radionuclide Toxicity "HEAST" Tables and EPA, Commonly Encountered Radionuclides for more information).

Like invisible popcorn that pops for thousands of years—if you get to close or ingest it while its still "hot" (decaying) you'll get burnt—enough "burns" and you'll die!

Hangar Compartment: tbd

Hangar Aft: tbd

Hangar, Lower: tbd

Hangar, Upper: tbd

Heave: up-down axis (See related terms Surge, Sway, Roll, Pitch and Yaw)

HY-80: High Yield steel used in the manufacture of Halibut's hull. This is very strong steel capable of withstanding up to ~80,000 pounds per square inch (PSI) of pressure [540 MPa; use 145.03 PSI ≈ 1 MPa].

Today, most submarines are manufactured using HY-100 or HY-130 and in a few cases titanium and other exotic metals. Use of the exotic metals is generally limited to smaller submersibles. Providing a useful lower cost method to research, develop, and test some of the exotic metals (in some cases non-metals, like composites) with promising characteristics, for application in submarine manufacture (see below graph comparing strength of HY-80, HY-130, Aluminum, Titanium, and composites GRP and CFRP).

Figure 5-1

Submarine Technology for the 21st, (2000), Trafford Publishing

For a current treatment of HY-80, HY-100, HY-130, HSLA (High Strength Low Alloy)-80, HSLA-100 see E.J. Czyryca, Advances in High-Strength Steel Plate Technology for Naval Hull Construction; Naval Surface Warfare Center: Key Engineering Materials Vols. 84-85 (1993) pp 491-520.

To learn more about the fascinating materials used to develop submarine hulls with low production and fabrication costs (a large cost driver is weldability), light weight, great strength [say 700 MPa minimum], and smallest sonar/radar/magnetic signature and cross-section, grab an introductory text on metallurgy of ferrous materials or carbon and alloy steels.

Of course submarine researchers and designers are interested in materials other than steel, which is heavy, corrodes, and has a large cross-section. However, its strength, relative ease of fabrication, and relative low cost makes steel the current preferred material.

The below tables summarizes some of the key trade-offs and concerns about using polymers—it doesn't matter how light your submarine is if a blast sinks it!

Table B-1
Polymers, Present and Potential Future Uses of Polymers by the Navy, Panel on Polymers, Naval Studies Board Commission on Physical Sciences, Mathematics, and Applications National Research Council, National Academy Press (1995)

Hydrodynamics, Principles of Submarine: Submarine hydrodynamic design principles dictate an optimal length to beam ratio (L:B) of 7.723. Halibut's beam was 29 feet making her optimal length approximately 224 feet. Halibut's actual length was 350 feet or 126 feet beyond optimal? The additional 126 feet was added when Halibut was modified for conducting "special operations". The special project's needs trumped optimal submarine design.

Reference: Concepts in Submarine Design.

Hydrodynamics, Principles of Submarine: tbd

Hydrostatics, Principles of Submarine: tbd

Hull, Submarine: tbd


Indiscretion Ratio (IR): The ratio of total time a submarine spends snorkeling to total time conducting operations. Often the IR is used to express the ratio of time a conventional (non-nuclear) submarine must snorkel to recharge its batteries to the time that recharge enable the submarine to remain submerged.

Nuclear submarines can snorkel, too. Recharging its batteries is not the only reason a submarine snorkels. The snorkel is not the only hoistable a submarine can rise above the surface while remaining submerged.

The concept is the same—a submarine conducting operations prefers to remain 100% submerged, 100% of the time—IR approaching zero—anytime a portion of the submarine is not submerged detection (indiscretion) is enhanced and the IR begins a positive increase.

If a submarine charges it batteries (indiscrete, snorkel above surface) for 1 hour and that enable the submarine to remain totally submerged (discrete) for 24 hours its IR is 4.1% (1/24 * 100) for that operation.

Ouestion: Is it possible for a submarine 100% discrete? Why|Why Not?

Insignia, Deterrent Patrol Pin:

The submarine deterrent insignia is formally known as the Fleet Ballistic Missile Breast Pin (FBMBP) and less formally as the SSBN Deterrent Patrol Insignia.

The pin records the number of "successful patrols" a submariner has made on a strategic ballistic missile submarine (SSBN) with the pin itself constituting the first "successful patrol". What constitutes a "successful patrol" is a "command decision" and some early SSBN patrols have been declared "successful" many years subsequent to the actual patrol. The early Regulus submarine missile deterrent patrols like those conducted by the USS Halibut SSGN 587 have not been so declared.

The FBMBP is independent of the submarine dolphin insignia so wearing the FBMBP in the absence of the dolphin insignia is not an uncommon event, as it may take more than one SSBN patrol to become a "qualified submariner".

There are six small holes at the bottom of the FBMBP to hold a combination of gold and silver stars. A gold star signifies one "successful patrol" and a silver star signifies five "successful patrols". As you might expect our Navy has a precise order for placing each gold and silver star (see Navy Uniform Regulation 5201 for the correct placement)

Some examples will illustrate:

A gold star in position one of the FBMBP represents two "successful patrols" (one for the pin and one for the gold star).

A silver star in position one and a gold star in position two of the FBMBP represents seven "successful patrols" (one for the pin, five for the silver star, and one for the gold star).

Three silver stars in position 1-3 and three gold stars in positions 4-6 of the FBMBP represents 19 "successful patrols" (one for the pin, 15 for the three silver stars, and 3 for the three gold stars).

After the declaration of an SSBN submariner's 20th "successful patrol" the silver FBMBP is exchanged for a gold FBMBP and the gold and silver star process repeats.

Generally speaking each "successful patrol" lasts between 75 - 90 days and may or may not be a "continuous patrol".

Sometimes sources will refer to a gold star as bronze or the silver star as signifying one successful patrol.

See also Wikipedia En, SSBN Deterrent Patrol Insignia

Insignia, Dolphins: tbd



Keel: The submarine's bottom side backbone running from the bow (front) to stern (back). The submarine's structural ribs (framing) are attached to the keel. Usually, it is the lowest part of the submarine. Although, on the Halibut the four skids on both sides of the keel, forward (front) and aft (back), protruded down another five feet.


Littoral: The United States Navy uses the rather expansive and vague definition of:

"Those regions relating to or existing on a shore or coastal region, within direct control of and vulnerable to the striking power of naval expeditionary forces."

LOFAR: Low Frequency Analysis and Recording is a method used by submarine sonar to select periodic signals (e.g. a ship or another submarine) from random background noise (e.g. ocean background).

As a signal decreases it becomes more difficult to differentiate it from random background noise—the signal to noise ratio becomes very small.


Magazine Size: tbd

Magnetic North: tbd

Maneuvering Room: tbd

Mare Island Naval Shipyard: Mare Island Naval Shipyard. Halibut's last home port and  site of decommissioning.

Master Diver: tbd

Metacenter, Submarine: See Center of Buoyancy

MidRats: Midnight rations.

A light meal served for submariners going on and coming off the midnight watch.

Usually consisting of a soup, some type of sandwich and drink like milk. If the pastry chef is in a good mood maybe a fantastic pastries.

Mooring Line: tbd


Negative Tank: see Tank, Negative

National Security Agency: tbd


Officer of the Deck: The person responsible for the entire submarine during a particular period of operation (typically four-hour segments. while "the captain" is ultimately responsible for the entire submarine, he delegates this responsibilities to others, usually officers. However, during periods of crisis and critical operations the captain will generally rescind his delegation and act as the officer of the deck, himself. For the Halibut this could mean things like an (de)anchoring operation, unexpected reactor shutdown (scram), high probability of collision, foreign or hostile contact, or fire, or emergency surfacing or ingress/egress into San Francisco bay and San Pablo Bay, unless relieved of navigation by a "local pilot". These delegations, rescissions, and relieve of duty are formal, ridged and recorded in writing. There is never a question or confusion about who has responsibility for the submarine during a particular period of time.

The officer of the deck stood his watch in the Halibut's control room.

Operations Compartment: tbd

Overall Range: tbd


Pelton, Ronald: tbd

Pitch: Rotation about the Sway axis. (See related terms Heave, Surge, Sway, Roll, Pitch and Yaw)

Plank Owner: A member of the submarine's commissioning crew—a tradition carried over from the wooden ship days.

Today, a plank owner certificate replaces the traditional piece of the ship's timber.

See also Wikipedia En, Plank Owner.

Poopy Suit: Blue very light-weight, dirt and fire resistant, fast drying, overalls worn by submariners while on patrols. Since water, laundry, and space is a luxury on most submarines, tough low maintenance clothing is helpful, convenient and appreciated.

Some enlisted submariners show up for months long patrols with little more than a tooth brush, several "poopy suits", a comfortable set of shoes (levis and t-shirt if there's a chance of going ashore), and as many books as their bunk tray will hold. Officers typically present a somewhat more formal appearance, but not always (on submarines appearance is never confused with respect for capability and talent).

Typically enlisted submariners voluntarily take turns standing "laundry queen watch" (generally those with relative fewer required watches) and do batches of laundry for other crew members whose watch schedule is more frequent.

Port: Left

Power Density: Reactor core power ouput per unit volume (e.g. 100 kWt/liter). (see also Toowiki, Power Density)

Pressurized Water Reactor: A fissile core and containment hardware which is moderated by pressurized water (in some cases heavy water H2).

A reactor can be generalized as creating a temperature gradient from which energy can be extracted for doing work. The limits on the maximum temperature differential between T1 and T2 are set by reactor design and type of moderator (neutron speed throttle) used—in Halibut's case a pressurized water moderator.

Suppose that under 2,200 psi Halibut's reactor was able to heat its heavy water moderator to 450 degrees Fahrenheit (T1) and cool it to 70 degrees Fahrenheit (T2). If some amount of energy Q1 is extracted and some amount of energy Q2 is returned to the gradient, then the amount of work (W) that can be performed (e.g. turning a shaft) is Q1 minus Q2, where Q1 is greater than Q2.

From Carnot we learned that a thermal reactor (engine) cannot have greater efficiency than W ÷ Q1 = 1− T2 ÷ T1.

Questions: Using the above equation can we say that as temperature T1 rises reactor efficiency increases? How about if T2 gets really cold? Can you convince yourself that the choice of a reactor’s moderator is a primary factor in reactor efficiency? Check out the very weird temperature characteristics of helium—would using helium as a moderator provide a larger temperature gradient? Would a helium moderator provide a more efficient reactor, all other things being equal? If yes, why?

Using the above temperatures (converted to absolute scale) for T1 and T2 calculate the theoretical maximum efficiency (W ÷ Q1) of Halibut's reactor. In reality Halibut's reactor was much less efficient than the "ideal" calculation.

If you are in high school see what W equals assuming you withdrew 370 degrees (remember to convert to absolute scale) Fahrenheit from the temperature gradient (Q1).

If you are interested in submarine reactors do some independent investigation (see the many books on Worldcat->Introduction to Basic Nuclear Engineering or Google Books->Nuclear Reactors) into what makes one moderator preferred over another (e.g. water verses heavy water or heavy water verses helium)—remember your reactor is inside a relatively small submarine, inside a gigantic pool of seawater, where survival and safety are primary concerns!

The above example alludes to one important characteristic of a moderator, how it interacts with neutrons released during the fission process (aka neutronics). How much and over what energy ranges does a heavy water moderator slow a neutron? Does one moderator gobble up more neutrons than another, if so over what energy ranges? Is a heavy water moderator preferred to light water, why? Is heavy water more expensive than light water and might this effect your decision? Is your choice of moderator determined by your choice or mix of core fissile matter or visa versa?

Presence, Submarine: tbd

Propeller: tbd

Propulsor, Propeller: See Propeller

Propulsor, Pumpjet: See Pumpjet

PV: tbd


Quartermaster: tbd

Qualified, Submarine: see "Dolphins, Submariner's"


RAD, Radiation Absorbed Dosage: The special unit for radiation absorbed dose, which is the amount of energy from any type of ionizing radiation (e.g., alpha, beta, gamma, neutrons, etc.) deposited in any medium (e.g., water, tissue, air). A dose of one RAD means the absorption of 100 ergs (a small but measurable amount of energy) per gram of absorbing tissue (100 RAD = 1 gray) --From U.S. Nuclear Regulatory Glossary--.

Reactor, Nuclear: see Pressurized Water Reactor

Halibut's reactor remains in its reactor compartment and is stored at the Hanford Site, Area 200, Trench 94 (218-E-12B) Hanford, Washington (aerial map of submarine reactor compartments) .

All American decommissioned nuclear submarine reactor compartments are stored at this site. Currently site 218-E-12B contains has approximately 119 submarine reactor compartments and growing.

Refueling (Recoring): tbd

REM, Roentgen Equivalent Man: The acronym for roentgen equivalent man is a standard unit that measures the effects of ionizing radiation on humans. The dose equivalent in rems is equal to the absorbed dose in RADs multiplied by the quality factor, Q, of the type of radiation (Q=1 for beta, gamma and x particles; Q=20 for alpha particles; Q=10 for neutron and high energy proton particles).--From U.S. Nuclear Regulatory Glossary and Regulations--.

Reynolds Number: A number used by submarine designers to evaluate the relation between an inertial force (like a submarine hull) and a viscous force (like sea water of a particular composition)—think of it as quantifying the drag and other forces which impede a submarine's ability to swimming like or better than a dolphin (submarine designers would be elated to achieve a dolphin's Reynolds Number).

Wikipedia has a Reynolds Number entry that need not be duplicated.

Repeaters, Signal: electronic devices attached to the Okhotsk communications cable to boost (amplify) the signals traveling through the cable. The repeaters reverse the undesirable effects of the signals attenuating (decay) as they traveled through the cable. (note: all "non-repeated" signals, traveling through the Sea of Ohkotsk cable, would decay and disappear into the cable's background noise before reaching their destination.)

Halibut used "inductive taps" to monitor and record the signals traveling through the Sea of Okhotsk cable. Its strong preference (subsequently a requirement) was for large, clean, noise free signals, with very little background noise. One method of satisfying this requirement was to tap the cable (or place the pv) as close as possible to a repeater. Thus, ensuring freshly boosted and cleaned-up (repeated) signals going to and from the Kamchatka Peninsula and Vladivostok . (i.e. good signal-to-noise.)

Locating and anchoring on the seabed over (or in some cases next to) one of these garbage can sized repeaters was a primary objective for the post regulus Halibut.
Question: Can you name two factors which determine the total number of repeaters attached to the Sea of Okhotsk communication cable? Can you name at least two factors which determine what subset of these repeaters the Halibut searched for and anchored over or next to?

Reserve Buoyancy: The submarine’s watertight volume above the Waterline, roughly equivalent to the Freeboard. Not all Freeboard, the portion of the submarine above the waterline, is necessarily watertight. Draft is the portion of the submarine below the Waterline.

Treating a submarine as a simple cylinder enables us to simplify the discussion and calculation of Reserve Buoyancy, without damage to the concept. Submarine designers use calculus and definite integral(s) to derive precise volumes for the specific submarine class hull shape.

Let’s assume our simple cylinder submarine has a Beam of 34 units, a Waterline of 26 units, a watertight Freeboard of 8 units that is 370 units in length. We can directly derive the percentage of Reserve Buoyancy, for our simple cylinder submarine, using the formula for a cylinder, (πr2h):

Reserve Buoyancy or the watertight volume above the Waterline, for our simple cylinder submarine, is (π x 82 x 370)/2 = 37,196 units (note: we treat this as a half cylinder with a radius of 8 units, with the waterline cutting the cylinder in half).

Total volume for our simple cylinder submarine is π x 172 x 370 = 335,921 units.

Percentage of Reserve Buoyancy is: 37,196/335,921 x 100 = 11.0%

All other things being equal a submariner prefers a submarine with the largest Reserve Buoyancy, Why?

A larger Reserve Buoyancy implies more of the submarine is above the Waterline and less Draft (note: The above calculations imply a Draft Volume, for our simple cylinder submarine, of 335,921 - 37,196 = 298,725 units). What does this imply about submarine surface speed. What does this imply about the submarine surface (submerged) stability? What does this imply about submarine center of gravity (buoyancy)? Is there a Reserve Buoyancy beyond which a submarine will not submerge? Discuss this in terms of submarine center of gravity and center of buoyancy?

Does the volume of the submarine’s ballast tanks above the waterline count in calculating Reserve Buoyancy, Why?

Roentgen: A unit of exposure to ionizing radiation. It is the amount of gamma or x-rays required to produce ions resulting in a charge of 0.000258 coulombs/kilogram of air under standard conditions. Named after Wilhelm Roentgen, the German scientist who discovered x-rays in 1895..--From U.S. Nuclear Regulatory Glossary--.

Roll: Rotation around the Surge axis. (See related terms Heave, Surge, Sway, Pitch and Yaw)

ROV: Remotely Operated Vehicle tbd - see also Basketball

Simple operational ROV Sea Perch educational kits are available for experimentation. DIY enthusiasts might want to check out OpenROV.

Rudder, Lower: tbd

Rudder, Upper: tbd


SBSD: Sea Based Strategic Deterrent is the name assigned to the follow-on submarine for the SSBN Ohio-class submarine.

Safety Tank: See Tank, Safety

Sail: tbd

Salinity: Salinity includes more than just salt. It includes the amount of all chemicals, (but, usually just the top 10 or 15 are included in the calculations), found in seawater, not including the water itself. Seawater salinity is typically a function of the seawater's conductivity (ie its ability to conduct electric current).

San Pablo Bay: San Pablo Bay

Screw: see Propeller

Sea-Dad: tbd

Sea of Okhotsk: Sea of Okhotsk - Wikipedia

Seals: Seals are inflatable packing, not unlike your bicycle’s inner tube, around Halibut’s two shafts. The seals seal the gap between the submarine’s hull and its rotating shafts (propellers).

If we trace shaft rotation (propeller rotation) we discover that it is ultimately turned by Halibut’s reactor. The reactor, using nuclear fission, heats the water flowing in the “primary loop” to high pressure steam. The super hot, high pressure steam in the primary loop heats the water flowing in the secondary loop to steam (primary and secondary loop steam do not mix). The steam in the secondary loop turns the turbine at a high rate of speed. The reduction gear (like your bicycle gears) turns the shaft at a low speed. The propeller attached to the shaft pushes Halibut through the water.

It is very difficult to simultaneously rotate the shaft and inflate the seals sufficient to prevent all seawater from leaking into your submarine. The seawater leaking into the submarine flows to the bilge which is then pumped back to the ocean. As long as you can pump out more seawater than leaks in you’re in good shape. Sometimes the seals cannot be inflated sufficiently and the leakage into the submarine exceeds the capacity of the bilge pumps. When this occurs, as it occasionally did on the Halibut, you immediately surfaced or reduced your depth (why?) and headed for port for repairs.

Sea Trials: tbd

Snell's Law: n1SinӨ1 = n2SinӨ2

SNR: Signal-to-Noise Ratio (aka S/N; Wikipedia)

Signature, Submarine: tbd

Sister Ship, Halibut: USS Seawolf SSN 575, Wikipedia

Skids: (aka tennis shoes or sneakers or skegs) The platforms attached to Halibut's forward and aft underside on each side of her keel. As part of Halibut's anchoring operation her buoyancy was continually monitored and adjusted to minimize skid load while maximizing her immobility on the seabed.

It was the COW's responsibility to tally and report on Halibut's buoyancy.

Scenario: You are the officer of the deck , quietly sipping your coffee, when you glance up at your television monitor and notice that a seabed rock has moved outside of the circle you drew around that rock two hours earlier. You suspect the camera taking the picture of the seabed may have moved? You ask winch control if the load on the anchors has recently spiked - you are told yes. You try to determine current direction from the seabed florae passing the camera, without success. You are now forced to stand and read the current direction and speed from the panel above your head. You discover that not only has the current changed direction, it has increased its speed by 1 knot! You now suspect the submarine has indeed moved. Just to be sure you switch to another camera and determine that another seabed rock has moved outside its circle. You are now confident that the submarine has moved and will continue to do so unless you do something. What do you do?

Snorkeling: This is exactly as one might imagine it, the submarine breathing while remaining submerged, just like when you snorkel in the pool. When the atmosphere "goes bad" (e.g. a fire, a piece of equipment burns up, or the atmospheric equipment malfunctions or exceeds its limits.) you must get fresh air. To get fresh air the officer of the deck will order the submarine to a depth of approximately 60 feet so the cow can raise the snorkel pipe. When the snorkel pipe is above the seawater the cow will turn on a huge fan. This fan is configured to simultaneously move air out of and into the submarine at very high volumes.

Scenario: You are Halibut's cook, preparing a fabulous fish dinner when the deep-fat fryer oil catches on fire. The entire submarine fills with thick smoke in seconds, the atmospheric equipment immediately exceeds its limits trying to remove the smoke from the air and gives up. Everyone has put on an emergency breathing mask in response to the fire alarm, and the cook is pissed because those extinguishing the fire also extinguished his fabulous dinner!

You are the officer of the deck when the COW screams through his emergency breathing mask that the fire in the galley is out - What do you do next? (hint: You will want to remove the smoke before the emergency air runs out, preferably immediately! Would your plan change if Halibut's divers were deployed?

Sonar, Ship's: tbd

Sonar, Ship's Side Look: tbd

Sonar, Towed Vehicle (fish) Side Look: tbd

Special Projects: tbd

Specific Gravity: The ratio of liquid densities. Distilled water is generally used as the reference denominator liquid density. So, a specific density of 1.0218 for sea water means it is more dense (.0218 more) than distilled water.

Spectrum, Submarine Communications (Based on Introduction to electronic defense systems):

Extreme-Low-Frequency, ELF 3-30Hz, submarine at depth
Super-Low-Frequency, SLF, 30-300Hz, submarine at depth
Ultra-Low-Frequency, ULF, .3-3KHz, submarine communications
Very-Low-Frequency, VLF, 3-30KHz, submarine communications
Low-Frequency, LF, 30-300KHz, atmospheric reflected communications
Middle-Frequency, MF, .3-3MHz, long range strategic communications
High-Frequency, HF, 3-30MHz, off-line-of-sight (OLOS) tactical ground communications
Very-High-Frequency, VHF, 30-300MHz, ground-to-air and line-of-sight (LOS) tactical ground communications
Ultra-High-Frequency, UHF, .3-3GHz, satellite and tactical ground-to-air communications
Super-High-Frequency, SHF, 3-30GHz, satellite communications
Extremely-High-Frequency, EHF, 30-300GHz, satellite communications
Blue-Green-Laser-Frequency, BGLF, 625THz, submarine communications

See also Wikipedia: Radio Frequency; Communication with submarines; Electromagnetic spectrum; Hertz (Hz); Handy Table of Known Electromagnetic Spectrum.

Speech Descrambler, Helium: A device which enables the speech communications of a saturation diver that is breathing a gas mixture, (In halibut's case helium and oxygen or heliox) to be understood by diver control.

Every child who has breathed the helium and oxygen mixture of a circus balloon is familiar with the "duck like" voice it causes. The speech descrambler generally uses modern vocoding techniques to restore heliox speech to normal speech.

Speed, Submarine Maximum: A submarine's maximum submerged speed equation well summarizes the trade-offs in submarine design and the enormous value of innovative advances of the state of art in submarine design:

Speed(max) = [cnPs/(1/2pCfA)]1/3 where c is a constant conversion factor of 550; n is propeller efficiency; Ps is the submarine maximum shaft horsepower; p is water density; Cf is a friction coefficient; and A is the total surface area of the submarine.

Using the above equation or the below simplified approximation, which nicely approximates a submarine's maximum speed can you describe and discuss some the many reasons why you might not what the "fastest" submarine?

Speed(max) ~ 25 * [Ps/LD]1/3 where Ps is the submarine maximum shaft horsepower; L is the submarine length and D is the submarine diameter (beam).

Speed, Submarine Maximum Quiet: Submarines trade speed for more noise—a submarine "faster" is a relatively noisier submarine—measured as increases in dB levels over specific frequency spectrum.

Each submarine and submarine class has a known speed, below its Maximum Speed, at which an increase in dB noise level begins to deteriorate its ability to "hear" surrounding signal emanations—that speed is referred to as the submarine's Maximum Quiet Speed.

The impact of the submarine's Maximum Quiet Speed depends on its environment and circumstances.

Question: Assume both submarines are at the same depth and want to "hear" each other at all times without being heard. What result if a trailing submarine's Maximum Quiet Speed is below (assume in Upper Area) a leading submarine's Maximum Quiet Speed (assume in Lower Area)?

What result if the opposite is true, the trailing submarine has the greater Maximum Quiet Speed? How would your response change if one or both submarines decided to use active sonar to "see" instead of just passively "hearing" each other? Is a submarine's Maximum Quiet Speed still relevant?

Spook's Room: A small room, within the operations compartment, used by NSA personnel for real-time listening and recording of the signals propagating to and from the Kamchatka Peninsula on the undersea Okhotsk's communication cable.

The spook room recorded using six-inch reel-to-reel tape recorders and quarter inch tape. The spook room recorded while Halibut was anchored onto the seabed.

Before de-anchoring from the seabed Halibut's special projects personnel would deploy a massive (transistor density for integrated circuits was at the macro-level of hundreds and thousand.) "pv" recording pod through the "aquarium".

Halibut's intrepid saturation divers lived in a small bathroom size chamber for months and where already "in the water" (two of four). As the heavy "pv" exited Halibut's "aquarium" the divers positioned it on the seabed, hooked up its inductive taps, disconnected the spook room taps, returned to their habitat, and Halibut headed for Guam or Mare Island.

The process was reversed when Halibut or a sister submarine returned - anchor onto seabed, deploy divers, connect the spook room taps, disconnect and retrieve the full "pv", sit on seabed filling-up spook room tapes, deploy and connect an empty "pv" to the cable, disconnect spook room taps, divers leave the water, de-anchor Halibut, and head for Guam or Mare Island.

The saturation divers were in the very cold water (at or near freezing) only during operations. When the divers were not “in the water” they read, played games (usually cards), ate, slept, shit, pissed, and chatted with their 24/7 dive controllers.

Divers could be rotated in an out of their saturation habitat in complex and dangerous compression and decompression cycles. These intrepid men lived to dive and being told, by their specially trained diving doctor or Master Diver, that they were not going into the water could and did produce disappointed toddler like reactions!

SSN: Ship Submersible Nuclear

SSBN: Ship Submersible Ballistic Nuclear

SSGN: Ship Submersible Guided-Missile Nuclear. Halibut began its life as an SSGN carrying Regulus I guided-missile. When the Regulus I and II programs were canceled Halibut was modified and re-designated as an SSN.

Today's SSGN's (four) are modified and re-designated SSBNs and primarily carry land attack cruise missiles. The SSGNs likely carry anti-ship, anti-aircraft, and anti-satellite missiles, too.

Stern Compartment: tbd

Stern Planes: tbd

Starboard: Right

Submerged Endurance:

Surge: forward-aft axis. (See related terms Heave, Sway, Roll, Pitch and Yaw)

Sway: port-starboard axis. (See related terms Heave, Surge, Roll, Pitch and Yaw)


Tank, Automatic Inboard Venting: tbd

Tank, Ballast: tbd

Tank, Negative: tbd

Tank, Torpedo Operating: tbd

Tank, Safety: tbd

Tank, WRT: Water Round Torpedo (WRT) tank was used in the "firing" of Halibut's torpedoes.

Most submarines, including Halibut, carry both nuclear and conventional torpedoes which can vary in weight from approximately 500 to 3,500 lbs depending on type and purpose.

"Firing" a torpedo means sending it from the inside of the submarine out into the surrounding sea, which is at a greater pressure (approximately 14.7 psi verses 26.4 psi, respectively.)

So, to do this a torpedoman must use a method to equalize the inside (14.7 psi) and outside (26.4 psi) pressures. Enter the WRT which is connected to the submarine's torpedo tubes.

The torpedoman opens the "inner" torpedo tube door and loads a torpedo into the torpedo tube (Halibut had 4 functional tubes in the torpedo room and 4 non-functional torpedo tubes in the stern room).

After the inner door is closed the torpedo tube is flooded and pressurize using 100 psi air and water from the WRT tank. When the inside of the torpedo tube reaches a pressure of 26.4 psi the pressure inside equals the pressure outside and the torpedoman opens the "outer" torpedo tube door (the inner and outer torpedo tube doors are NEVER opened at the same time while the submarine is at sea, why?).

Now the torpedoman must have a method of moving the torpedo out of the torpedo tube and into the sea - heavy objects tend not to move unless acted upon by some force! With the water in the torpedo tube, WRT tank, and sea pressure all sitting at 26.4 psi the heavy torpedo will just sits there, unless acted upon by a force.

Enter the WRT, again, but this time using 3000 psi air instead of 100 psi air. The 3000 psi air is connected to the WRT using a pulse piston. One side of the piston is connected to the WRT (remember you pressurized the WRT to 26.4 psi using 100 psi air). The other side of the pulse piston is connected to the 3000 psi air manifold.

The torpedoman when told to "fire" a torpedo moves the pulse piston sending a pulse of 3000 psi air into the WRT tank which immediately raises the pressure in the WRT from 26.4 psi to 3000 psi! This violently exploding and expanding air follows the path of least resistance and forces water from the WRT, torpedo tube, and out into the surrounding sea where it can continue expanding.

Even a one and a half ton torpedo is no match for this type of force and it’s flushed out of the torpedo tube along with the water and anything else in the WRT or torpedo tube!

After being force out of the torpedo tube and into the sea the torpedo will start its own engine that self-propels it toward its target.

Question: What would happen if the torpedoman after loading the torpedo, closing the inner torpedo tube door, and pressurizing the WRT forgetting to open the outer door before "firing" the 3000 psi pulse piston (hint: how would the increased WRT and torpedo tube pressure vent)? Do you suppose there are safety interlocks which prevent a torpedoman from doing this?

When a torpedoman goes through the entire process of firing a torpedo, but there is no torpedo in the tube it is called firing a “water slug” – they do this to test the system to ensure it is working properly, among other reasons (can you think of some of those other reasons?).

Note: Some torpedoes are designed to “swim” out of the torpedo tube instead of being “fired” out. Swimming out just means that the torpedo starts its engine while still sitting in the torpedo tube and propels itself out of the torpedo tube. Can you think of some reasons why this might be more dangerous than using a 3000 psi air pulse to fire it out?
(see related, Automatic Inboard Venting (AIV) and Torpedo Operating (TO) tanks)

TAPS: Torpedo Advanced Propulsion System (Not to be confused with Taps)

Tennis Shoes: see Skids

Thermocline: tbd

Thermohaline: Water's motion as a function of differential temperature and salinity. Stated differently, areas of cold, high salinity water sink faster than areas of warm low salinity water.

Thrusters, Horizontal: tbd

Torpedo: Wikipedia, Torpedo. Halibut carried MK-48 torpedoes.

Torpedo Compartment: see Compartment, Torpedo.

Transponder, Underwater: An underwater device that emits a unique signal, either continuously, periodically, or when queried (pinged), used to mark a particular location of interest on the seabed.

Halibut used transponders to mark the general location of a seabed targets when mapping a search grid onto the seabed. Halibut would then return to each unique transponder for closer inspection of the marked target.

Transponders eliminated the need to conduct costly, time consuming, and boring search and grid operation – once a target was found it stayed found.

On Halibut the transponders left the submarine through the GDU. Because Halibut’s GDU worked pointed down toward the keel transponder launch was convenient and relatively accurate.

True North: tbd


Underway: tbd

Uplink: tbd


Valve, Ball: tbd

VTRs: Video tape recorders. Halibut used two vtrs with twelve inch reels, containing one-inch tape, to record images of interest.

When Halibut returned from a deployment, crates of vtr reels, containing images, where off-loaded onto an awaiting flatbed truck, for delivery to their joint-agency sponsors (Navy, NSA, and CIA). (the smaller reels used, by the spook room , to record the cable signals where also included in these crates.)


Wardroom: tbd

Waterline: tbd

Water Slug: The process of firing a torpedo, without a torpedo in the torpedo tube. This is generally done to test the system and results in a large group of bubbles going to the surface.

It can also be done to eject to the sea whatever has been place in the torpedo tube prior to firing the water slug.

Weight Budget: The process by which a submarine designer assigns and tracks the submarine's weight.

A typical weight budget might include the following top level categories. Modern weight break-down structures use powerful databases and design software, with sophisticated features1 to help submarine designers precisely assess and understand the trade-offs implicit in a submarine's weight-buoyancy equilibrium:

1. Hull Structure
1.1 Hull
1.1.1 Stiffener Ring Stiffeners Radial Stiffeners
1.2 Bulkheads
2. Propulsion System
2.1. Reactor
2.1.1 Core
2.1.2 Shielding
2.2 Turbine
2.2.1 Blade
etc. in excruciating detail, as required
3. Electrical System
4. Control Communications Systems
5. Submarine Services
6. Outfit and Furnishings
7. Armaments
8. Ballast
8.1 Permenant Ballast
8.2 Margin Ballast
9. Variable Weights
9.1 Variable Ballast
9.2 Stores
9.3 Crew
10...N etc. in excruciating detail, as required

The Halibut is a one in a class submarine and is not typical of a modern fast-attack weight allocation.

A typical post Skipjack-class (tear-drop envelop using nuclear fuel, Wikipedia, US List Submarine-classes) submarine's might allocate weight as follows:

Structure - 45% (of which the pressure hull is 50%)
Payload - 8%
Machinery - 35%
Accommodations - 4%
Stores - 2%
Ballast - 6%

note: The weight budget module is part of larger suite of software used to accurately (within margins) design and sea-trial a submarine over its life-cycle before one part is ordered or manufactured!

If a change occurs, however trivial (say, because women begin crewing on submarines), the weight budget is updated and the software suite recalculates and redraws the entire submarine design. Changes to a prior baseline are accumulated and made in blocks at some future date.

Categories partially based in part on Burcher, Roy; Rydill, Louis, Concepts in Submarine Design, Cambridge Press 1994

Winch Control: tbd

WRT: see Tank, WRT.


X-Y Plotter: tbd


Yaw: Rotation about the Heave (up/down) axis. (See related terms Heave, Surge, Sway, Roll, and Pitch)


Zulu Time: Submarines routinely cross many time zones as they move about the oceans conducting their missions. Without a way of synchronizing time across all time zones things would become hopelessly confusing as each submarine used its unique time in its unique location.

To achieve uniformity and synchronization the military uses the concept of "Zulu Time" (civil aviation uses the equivalent Greenwich Mean Time) and every submarine, regardless of its location communicates in Zulu Time (i.e. the time in Greenwich, England or Zero Degree Longitude)

Submariners are legendary for playing practical jokes on each other, some actually very sophisticated involving weeks or months of planning involving large numbers of crewmembers, except the hapless target of the joke!

One of the less sophisticated, but nevertheless effective jokes, involve convincing a new crewmember to go throughout the entire submarine resetting clocks as the submarine crosses the international dateline (approximately 180 degrees longitude).

To experience the full pleasure of the joke you have to be in the control room when the various new watches call (they are broadcast so everyone hears, unless turned off) asking why some idiot is demanding to reset their clock forward or backward 24 hours. The watch is informed a practical joke is underway and the hapless crewmember is permitted to reset the clock and sent on his way.

A call from the captain and a terse "knock it off" immediately truncates that practical joke.

Sometimes it was the captain who was the target. He would usually disguise any irritation, opting to treat it as an opportunity to build crew cohesion and camaraderie.
If you have a submarine term you want defined or you have defined a submarine term you want included send it along as a comment.

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