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Submarines used in the two world wars could remain underwater only a few hours at a time and had to function at the surface for long periods, so they had sharply pointed bows and long, slender hulls.
BASIC SUBMARINE STRUCTURE
A submarine is fundamentally an air space contained by a hull that is designed to withstand deep ocean pressures and to move easily underwater. The hull is a double steel shell. The inner, or pressure, hull contains all the machinery for propelling and guiding the vessel, plus living quarters for the crew. The outer hull holds the ballast tanks. When the vessel submerges, these tanks are opened and flooded with seawater. For surfacing, the seawater is forced out of the ballast tanks and replaced by compressed air.
Flooding the ballast tanks is only one step in the process of submerging. The submarine is also propelled downward by rear-mounted propellers that force the craft forward, and by diving planes, which are movable horizontal rudders that direct the angle of the dive. When the desired depth is reached, the water level in the vessel's trim tanks is adjusted to keep the craft stable.
Nonnuclear submarines are propelled on the surface by diesel engines; when submerged, propulsion is provided by electric batteries and motors. The batteries must be recharged on the surface by the diesels after a short running time.
Until after World War II, submerged submarines were navigated with a simple magnetic compass, supplemented by periscopic sextant shots and observation of the shoreline. Most periscopes could not be used at depths greater than 9 m (30 ft).
Improvements in gyroscopic navigational aids ultimately led to the development of modern inertial navigation systems capable of providing accurate guidance without the need for frequent external "fixes" (see GUIDANCE AND CONTROL SYSTEMS).
The Conning Tower
The fin-shaped superstructure mounted on top of the submarine serves as a bridge when the vessel is on the surface. It holds a number of instruments: the periscopes, the various radio and radar antennas, and the snorkel, a system of air intake and exhaust pipes. On nuclear submarines the conning tower is known as the "sail" and carries a set of diving planes.
World War I
From the early years of the 20th century, fleets of submarines were built by every major European power. The German vessels were the most efficient; by 1911, German designers had abandoned both steam and gasoline--which was volatile and therefore hazardous within the confines of a submarine--and had equipped all their vessels with diesel engines. Also, German periscopes were the best in the world.
World War I provided the first opportunity to use submarines as attack vessels on a large scale. With its fleet of U-boats (Unterseebooten), Germany came close to severing Britain's overseas lifelines. The British countered with DEPTH CHARGES and hydrophones--underwater listening devices--and with killer submarines--small antisubmarine vessels that could maintain underwater speeds of up to 15 knots for as long as two hours. Finally, merchant sailings were concentrated into large, well-escorted convoys, a tactic for which the Germans had not found an answer by the war's end.
World War II
As in World War I, Germany began World War II with a small but seasoned submarine force and immediately applied it to isolate Britain from overseas resources. Britain again replied with heavily escorted convoys, and the Germans responded by sending U-boats out in large "wolf packs" that searched and attacked in concert.
Tactical complexities multiplied: hydrophones were supplemented by underwater sound-ranging systems (SONAR), and the use of RADAR and radar warning devices became widespread. The Germans used long-range search aircraft to coordinate the wolf packs; the British and Americans replied with antisubmarine aircraft carriers and fleets of hunter-killer submarines that were guided to the German vessels by sensitive direction-finding radios installed aboard surface vessels.
American submarines in the Pacific and British submarines in the Mediterranean enjoyed the success denied the Germans in the Atlantic. Submarine destruction of Axis supplies played a major role in the Allied victory in North Africa. American submarines effectively halted Japanese maritime commerce by mid-1944. Britain and Italy both had isolated but spectacular successes with miniature one- and two-man submarines in port attacks on enemy ships.
Source: John F. Guilmartin, Jr. , Submarine; from "The Academic American Encyclopedia" (1995 Grolier Multimedia Encyclopedia Version), copyright (c) 1995 Grolier, Inc. Danbury, CT
AMERICAN NAVAL POWER:
Tour a real WWII American submarine, the USS PAMPANITO (SS-383)
DR. SLEEPER NOTE: We are maintaining an edited record on this server of certain technical information and operational procedures relative to this class of American boat. This is particularly important material for writers and researchers. A greatly detailed, highly interesting, multi-media tour of the Pampanito is maintained by The National Maritime Museum Association on Pampanito's newest site (http://www.maritime.org/pamphome.shtml)
Go see the site, and then go to San Francisco's Fisherman's Wharf and see this legend! I believe that it is the only good example of this class submarine remaining afloat in the world. This is the same sub used in the movie "Down Periscope", starring Kelsey Grammer AND it is one of the submarines mentioned in our currently reviewed book selection: "Clear the Bridge! The War Patrols of the U.S.S. Tang" by Rear Admiral Richard H. O'Kane, USN. US subs contributed more to the sinking of Japanese tonnage (55%) in World War II than any other war-fighters that we had in our arsenal.
MAIN SUBMARINE SYSTEMS
TRIM AND DRAIN SYSTEM: The trim system is used to stabilize the submarine by moving water ballast to various trimming tanks located throughout the boat. The drain system is used to drain water from condensation, leakage from hatches during diving and surfacing operations, the escape trunk, and to pump the bilge overboard.
TANK ARRANGEMENTS: Water ballast, fuel oil and trim tanks are located between the pressure hull and outer hull. Miscellaneous storage tanks for fresh water, lube oil, torpedo alcohol, and sanitary waste are located within the pressure hull.
STEERING AND DIVE PLANES: These systems control the vessel on the surface and when submerged. There is one large rudder on the stern to control the course. The two fixed stern planes mounted aft of the propellers and the two retractable bow planes control the vessel when submerged.
WATER SYSTEM: Fresh water is either stored or distilled from sea water on-board for use in drinking, cooking, washing, cooling engines, and for use in the storage batteries and steam powered Mark 10 and 14 torpedoes.
VENTILATION AND EXHAUST SYSTEM: Air is supplied through a thirty-six inch valve located in the after end of the conning tower. Air is supplied to the engine rooms, and bypass air to the maneuvering room, through piping and valves at the top of the pressure hull. Ship's supply and exhaust blowers are located in the forward engine room, and battery exhaust blowers are located in each battery compartment.
Four main diesel engines turn generators which supply power for the electric propulsion motors, or to charge large storage batteries. The submarine is always operated by electrical power, the engines do not turn the shafts directly. When the submarine is on the surface, electric power is supplied by the generators and when submerged, power is supplied by the batteries. There are four propulsion motors, two connected to each of the two shafts through reduction gears. The reduction gears reduce the motor speed of approximately 1,300 revolutions per minute (rpm) to the propeller speed of 280 rpm. The next class of submarine, the Tench class, used two low-speed double-armature motors hooked directly to the shafts.
MAIN GENERATORS: Four main Elliot generators produced 1,120 kw at 720 rpm, and 900 kw at 650 rpm. There is one generator coupled to each of the four main diesel engines. A single main generator, or any combination, can be used to charge the main storage batteries or power the main propulsion motors.
AUXILLIARY GENERATOR - One Elliot generator rated at 300 KW. The auxiliary generator, powered by the auxiliary engine, supplies power for all auxiliary circuits, charges the main storage batteries at a low rate or can be used to power the main propulsion motors through the batteries. (DR. SLEEPER COMMENT: This got a lot of use on the USS Tang. Read the book.)
MAIN ELECTRIC MOTORS - Four main Elliot motors rated at 1,375 horsepower each.
DIESEL ENGINES: Four main Fairbanks-Morse 10-cylinder opposed piston 38D - 8 & 1/8" two-cycle diesel engines. The main engines produced 1,600 horsepower at 720 rpm, and 1,280 at 650 rpm.
AUXILIARY ENGINE: one 7-cylinder Fairbanks-Morse opposed piston 35A - 5 & 1/4" diesel engine.
BATTERIES - Two 126-cell storage batteries. Each cell is 15" deep, 21" wide, 54" tall and weighs 1,650 pounds. The plates are immersed in an electrolyte solution made up of pure water and pure sulfuric acid... Each cell produces approximately two volts and are permanently wired in series. Each of the two battery groups could be operated independently or in parallel. This means that the submarine could travel submerged at 11 knots for one hour or could travel 95 miles at a speed of 5 knots before the voltage falls to a limiting voltage. TOTAL SHAFT HORSE POWER: 5,400 surfaced, 2,740 submerged.
Navigation systems include the gyrocompass and repeaters, the dead reckoning system, underwater log, LORAN, magnetic compass, and sextant.
The Arma Mark IIV Gyrocompass is an inertial guidance system used to determine the movements of the boat when underwater. There are various repeaters about the boat.
The gyrocompass receives its directive from a high speed spinning gyroscope driven by electric motors. When any object is spinning rapidly it tends to keep its axis pointed in the same direction. The gyrocompass consists of a spinning gyroscope, made north seeking by placing a weight below the axis, which is mounted in gimbals so that the movements of the submarine do not effect its position. A dial mechanically connected to the gyrocompass has the points of the mariner's compass marked on it and indicates the submarine's true course.
The Arma Mark IIV, Class 3 Dead Reckoning Tracers (DRTs) in control room and the conning tower were used to plot and keep track of the boats position and the positions of other ships.
The dead reckoning system consists of a dead reckoning analyzer indicator in the control room and two dead reckoning tracers, one in the control room and one in the conning tower. The system, when properly set at the starting point, indicates at all time the latitude and longitude of the submarine on dials in the analyzer and traces the ship's movements on a chart placed on the tracer.
LORAN is a navigational system for determining position by means of radio. The word is derived from the first letters of the words "LOng RAnge Navigation." The principal of operation is based on the difference in travel time (in millionths of a second) to the point of observation, of radio signals from two transmitting stations located several hundred miles apart. The intersection of two or more of these lines determines a "fix" in the conventional manner.
For more traditional means of navigation the submarine carries a magnetic compass in the conning tower, a chronometer and a sextant for celestial navigation.
The essential function of the periscope is to give an officer conning a submarine a view of the surrounding horizon while the vessel is submerged.
The periscopes are about forty feet long and when lowered rest on rubber bumpers at the bottom of the pressure hull. When they are raised they pass through packing to prevent leaking and several brass bearings in the support housings, or shears. They are filled with dry nitrogen to prevent fogging.
The periscopes were also used as part of the fire control system and could be used to determine the range and bearing of a target. The after scope, or attack scope, is fitted with an optical range finder to determine the range to the target. The forward, or general observation scope, is fitted with ST radar and provided very accurate target ranges.
COMMUNICATIONS AND CRYPTOGRAPHY
EXTERIOR COMMUNICATIONS are achieved with the main radio transmitter and receivers and the electronic cipher machine (ECM.)
Pampanito is equipped with what was, during the war, state of the art radio equipment. While primitive by today's standards the radio equipment used was rugged and reliable. The submarine carried a TBL transmitter, designed and constructed by the Westinghouse Electric Co. The transmitter was in effect two transmitters housed in a two part cabinet that measured 72" high by 32" wide and weighed 804 pounds. Power for the transmitters was provided by a motor-generator set usually located in the pump room. ...The TBL-7 is the main transmitter for the boat, it could be used to send Morse code (CW), or voice (AM).
The principal radios used for communications on Pampanito, as well as on many classes of surface vessels were the RAK /RAL series of receivers. Very similar in design and appearance the principal difference in these receivers was the frequency coverages. The RAK covered 15 to 600 kilocycles while the ral covered .3 to 23 megacycles. The RAK/RAL receivers were designed to operate from 115 volt, 60 cycle alternating voltage supply lines. In emergency they could be operated from batteries. ...Neither receiver had a calibrated tuning dial but required the use of a separate frequency standard to set the desired receiving frequency. This frequency standard, also necessary for the operation of the TBL transmitter is known as the LM frequency meter. The purpose of the LM frequency meter is to provide an accurately calibrated radio frequency signal that is very stable.
In use the LM would be set, by means of its individual calibration chart to the desired operating frequency, and this signal would be used to tune the transmitter and receiver. In addition to the calibration chart, the LM had an internal crystal controlled oscillator to provide very accurate check points a 1000 kilohertz intervals. The LM was originally designed for aircraft use by the Bendix Corporation. The RAK/RAL series of receivers was manufactured by the Radio Corporation of America. (DR. SLEEPER COMMENT: RCA)
...The RAK-6 radio was used to receive Morse code (CW) messages ...less often it was used for to receive voice. This radio was usually paired up with an RAL to cover a wider frequency range. The RAL-6 radio was used to receive Morse code (CW) or voice messages...
In addition to the RAK/RAL, Pampanito carried radio receivers that were designed for long and short-wave broadcast reception. These included the RBO/RCH/RCB series of equipment. Pampanito has an operational RBO built by the H.H. Scott Company, and an operational RCH built by the National Corporation. The RBO radio was used as a entertainment receiver and is located in the crew's mess. The speaker amplifiers were used to distribute its signal throughout the boat.
The ECM Mark II cipher machine was used to encrypt outgoing messages and decrypt incoming messages. When sending a message, the text was typed on this machine by an officer and the ECM Mark II printed out a cipher text version of the message. This was then handed to a radio operator who used Morse code to send the message. The reverse process was used to receive a message.
The RBH-2 radio was used as a general purpose receiver.
When commissioned in 1943 the Pampanito also carried a VHF AM radio transmitter/receiver for communication with aircraft and other submarines and surface vessels with similar type equipment. The AN/ARC-4 radio was primarily used to send and receive messages to aircraft. This was used for "Dumbo" duty when the submarine waited off the coast of enemy territory to rescue downed airmen.
The ABK-1 IFF (Identification Friend or Foe) transponder was used to identify the boat as friendly to other compatibly equipped forces. (In the control room.)
The BN IFF (Identification Friend or Foe) interrogator/responder was used to identify aircraft or other boats with compatible systems as friendly. Its information is displayed on the radar displays. (In the control room.)
The AN/APR-1 Radar countermeasures was used to identify radar signals from other ships or aircraft. (In the control room.)
The Bathothermyograph CBT40131 was used to chart the temperature of the water. This information could be used to find changes in temperature that would bend sound waves that were used by the enemy to locate the boat. (In the control room.)
Submarine Signal Corporation Depth Sounder - This was used to determine how deep the water was beneath the keel. (In the control room.)
INTERIOR COMMUNICATIONS SYSTEMS include the general announcing system, alarm systems, sound powered phones, and telephone call system.
The general announcing system is comprised of two voice communications circuits, one-way (1MC) and two-way (7MC). The same amplifier equipment is used for both circuits.
The alarm system is made up of three alarms: the diving alarm, collision alarm and the general alarm. The diving alarm is a series of motor driven alarms located throughout the submarine with a distinctive "ah-oo-ga" sound. Both the general alarm and the collision alarm are produced by signal generators located in the amplifier stack and sound through 1MC speakers or horns in each compartment. The general alarm is a gong sound at 100 beats a minute that is sounded for ten seconds. The collision alarm is a rising siren signal.
The sound powered phone system is a telephone system in which the power comes from the sound of the voice. Vibrations from the voice cause a diaphragm to vibrate. Attached to the diaphragm is a delicate needle, or armature, that is surrounded by a fine wire coil held in place by a magnet. The movement of the armature inside the coil induces current which is transmitted through the line to a receiver. The receiver is constructed exactly like the transmitter. The current from the transmitter passes through the coil on the receiver and causes the diaphragm to vibrate and reproduce the speaker's voice. The system is divided into two circuits, the XJA (handset) used for routine ship's service communication, and the JA (headset) used on all battle control stations.
The telephone call system consists of hand cranked signal generators located in each compartment and require no supply voltage. Often refereed to as "growlers" each unit consists of a selector rotary switch used to select the compartment desired and a small speaker that "growls" on the receiver unit to notify the compartment of an incoming call. It is a separate complete circuit and is not connected to the phone systems.
THE TORPEDO DATA COMPUTER (TDC) By Terry Lindell
The TDC was unique in World War II. It was the computational part of the first submerged integrated fire control system that could track a target and continuously aim torpedoes by setting their gyro angles. The TDC Mark III gave the U.S. fleet submarine the ability to fire torpedoes without first estimating a future firing position, changing the ship's course, or steering to that position. Instead of hoping that nothing
in the setup changed, a fleet submarine with the TDC could fire at the target when the captain judged the probability of making hits to be optimal.
In World War II a torpedo's gyro angle was set mechanically while it was in the tube. A shaft, known as the spindle, slipped into a socket near the housing of the torpedo's course gyroscope. When the fire control system rotated the shaft, the gyroscope rotated. After being fired, the torpedo traveled on a straight course for a known distance called the reach. A delay in the release of the torpedo's gyro steering mechanism by a threaded shaft determined the magnitude of the reach. Once engaged, the steering mechanism brought the torpedo to a new course based on the angular offset of the gyroscope.
The Mark III computer consisted of two sections, the position keeper and the angle solver. The position keeper tracked the target and predicted its current position. To do this, the position keeper automatically received input of the ship's own course from the gyro compass, and own ship's speed from the pit log. The position keeper had hand cranks on its face that set the target length, estimated speed, and angle on the bow. It also contained a sound bearing converter that calculated the target's location based on sonar measurements.
The position keeper solved the equations of motion integrated over time. The result was a continuous prediction of where the target was at any instant. Successive measurements of the targets' position were compared to the position keeper predictions and corrections for error were introduced with the hand cranks. The predicted target position became more accurate as more measurements made the corrections smaller. It was typical to get an accurate track on the target after about three or four observations under good conditions.
The angle solver automatically took the target's predicted position from the position keeper, combined it with the tactical properties of the torpedo, and solved for the torpedo gyro angle. Values calculated from this solution were returned to the position keeper... The gyro angle automatically went to each of the torpedo rooms and set into the torpedoes continuously. The TDC controlled both torpedo rooms and all 10 torpedo tubes at once.
The TDC Mark III was the only torpedo targeting system of the time that both solved for the gyro angle and tracked the target in real time. The comparable systems used by both Germany and Japan could compute and set the gyro angle for a fixed time in the future, but did not track the target.
The Arma Mark III, Mod 5 Torpedo Data Computer in the conning tower ...(with) The Gyro setters ...in the forward torpedo room (and)...in the aft torpedo rooms.
The Type 51011 Torpedo Battery Charger with Type 510008 Controller were used to charge the Mark 18 torpedo batteries. ...two sets in the forward torpedo room and one in the aft torpedo room.
The Type 5102 Hydrogen Burning Wire Controllers ...(one) in the forward torpedo room and ...(one) in the aft torpedo room were used to avoid the buildup of explosive hydrogen gas while charging Mark 18 torpedos.
The Bendix Pit Log was used to determine Pampanito's speed through the water. The master controller is in the forward torpedo. ...Indicators in the conning tower and control room.
The Hydrogen Detector type N.H.D. was used to detect the build up of explosive hydrogen from the main batteries. It is located in the control room.
WEAPONS AND FIRE CONTROL
Pampanito's main weapons are torpedoes, main deck gun, anti-aircraft guns, and small arms. Pampanito carried both the Mark 14 steam powered torpedoes and the Mark 18 electric torpedoes. On her forward main deck she is fitted with a four-inch / fifty-caliber deck gun. On the elevated gun decks she carries a twenty millimeter gun forward and a forty millimeter gun aft. Below deck the magazine was equipped with a variety of small arms ranging from handguns, twelve gauge shotguns and fifty caliber machine guns.
The torpedo tube is very similar to a large naval gun. It is a long tube made of bronze with a muzzle, or outer door, and a breech, or inner door. As a gun fires a shell so does the torpedo tube, using compressed air rather than explosives for the purpose. One marked difference, however is that the tubes projectile, the torpedo, is self-propelled. The tube is used only to push the torpedo out of the submarine.
TORPEDO TUBE FIRING PROCEDURE:
With the muzzle door closed, the breech door is opened and the torpedo is loaded into the tube. The breech door is then closed and the muzzle door can then be opened safely.
At any depth the sea pressure prevents the muzzle door from opening. To offset this external pressure an equal pressure is obtained within the tube by admitting water from a tank (displaced air is vented inboard) and then opening a valve to the sea to equalize the pressure.
When the tube is flooded and the pressure is equalized, the muzzle door can be opened and the torpedo is ready to fire.
The compressed air valve is opened and the torpedo is ejected from the tube. The air is not permitted to completely fill the tube, but is vented off inboard so that a bubble does not escape into the sea and rise to the surface giving away the position of the submarine.
The compressed air is shut off and the tube fills with sea water. This offsets the lost weight of the torpedo and keeps the submarine in trim.
The muzzle door is then shut and a valve to a drain tank is opened to allow the tube to drain. The breech door can now be opened and the tube reloaded.
The fire control system consists of the periscopes, target bearing transmitters mounted on the bridge and after gun deck, (a) Torpedo Data Computer in the conning tower, and gyro angle regulators in each torpedo room.
DIVING AND SURFACING
When the submarine is traveling on the surface, it is operated like any other boat with one major exception; it has flood ports along the bottom that are open to the sea. The sea is prevented from filling the ballast tanks because they are closed at the top, much like holding a drinking glass upside down under water. There is no place for the air to escape because vents along the top of the tank are kept closed. The surfaced submarine maintains positive buoyancy by riding on a bubble captured in the ballast tanks.
The submarine achieves a dive by opening the vents and allowing the air to escape and water to fill the ballast tanks. The bow planes are lowered and angled down to drive the submarine below the surface. Once submerged, the boat is trimmed, or balanced, by pumping water between trim tanks. Over-all trim is the process of attaining neutral buoyancy; final trim is the establishment of fore and aft equilibrium, or zero bubble, with neutral buoyancy. The submerged submarine is operated at neutral buoyancy and control of the vessel is obtained by the rudder and the bow and stern diving planes. A zero bubble should be maintained without excessive angles on the diving planes. The primary effect of the bow planes is on the depth, and the primary effect of the stern planes is on the angle of the submarine.
Negative buoyancy for a quick dive is achieved by flooding the negative tank which is located at the keel slightly forward of the center of the boat, adding a slight down angle to the submarine. The negative tank is blown free of water once submerged.
Pressure on the hull increases with depth. The total pressure that the hull must be able to withstand is measured by the difference between interior hull pressure and the external pressure at a given depth. When the maximum depth is passed, the pressure hull will be crushed.
Surfacing must be done with caution. The submarine is first brought to periscope depth and a thorough search is made of the surrounding area. When assured that surfacing is safe, the preliminary order, "Stand by to surface," warns the personnel that the signal may be expected. At the sounding of the signal, three blasts of the diving alarm, or the, passing of the word "Surface, Surface, Surface," the various actions necessary are performed.
The bow planes are placed on ten degrees dive and rigged in automatically unless the conning officer gives other instructions. A report, "Bow planes rigged in," is made to the conning officer. Speed is increased to about 6 knots to give maximum lift. Due to the up-angle on the ship, the increased speed makes the inclined surface of the hull effective and the resultant lift raises the ship, The stern planes are used to limit the upangle to about 5 degrees. The up-angle may be increased by blowing the bow buoyancy tank. Blowing the safety tank increases the positive buoyancy. However, this is not usually done. The main ballast tanks are partially blown to surface normally. After surfacing, the high-pressure air is secured and the blow is completed with the low-pressure blowers. Sealing the lower conning tower hatch permits immediate opening of the upper hatch since the relatively small volume of air in the conning tower can be released without danger. This procedure expedites the movement of personnel to the bridge.
When the decks are awash, the conning tower hatch is opened and the commanding officer goes to the bridge. In the meantime all stations, are alert and prepared to dive at once. The safety of the ship demands that nothing interfere with an emergency dive, should it become necessary. When the commanding officer is satisfied with surface conditions, the announcement, "All clear" will indicate that the submarine is to remain on the surface and the remainder of the surfacing routine is carried out.
During this interval, the low-pressure blowers, using air from within the ship, are completing the blowing of the main ballast tanks and reducing the pressure within the hull. Usually the pressure is equalized before the lower conning tower hatch is opened. The engine air induction and hull outboard ventilation valves are opened on orders from the bridge. Propulsion is shifted to the main engines from the batteries. The safety tank is flooded, the low pressure blowers are secured after 15 minutes running, or when the tanks are dry, and normal surface routine is again assumed.
DIVING AND SURFACING PHRASEOLOGY
a. "Rig ship for dive." The order to carry out the preparations for diving.
The definitions contained here are exact meanings of the terms commonly used in reference to World War II submarines and their operation. These terms and explanations represent accepted interpretations and provide an understanding of the functions of the equipment.
Surface condition. A submarine is in surface condition when she has sufficient positive buoyancy to permit running on her main engines.
Diving trim. The term diving trim designates that condition of a submarine when it is so compensated that completing the flooding of the main ballast, safety, and bow buoyancy tanks will cause the vessel to submerge with neutral buoyancy and zero fore-and-aft trim.
Rigged for dive. A submarine is rigged for dive by so compensating the vessel and preparing the hull openings and machinery that the vessel can be quickly and safely submerged and controlled by flooding the main ballast tanks, using the diving planes, and operating, on battery-powered main motors.
Running dive. A running dive consists of submerging a submarine while running on battery power.
Stationary dive. A stationary dive consists of submerging a submarine without headway or sternway.
Quick dive. A quick dive consists of rapidly submerging a submarine while running on main engines.
Submerged condition. This term designates a condition of a submarine in which all fixed portions of the vessel are completely submerged and the variable ballast is so adjusted that the submarine has approximately neutral buoyancy and zero fore-and-aft trim.
Final trim. Final trim is the running trim obtained after submerging,, in which the fore-and-aft and over-all weights have been so adjusted that the boat maintains the desired depth, on an even keel, at slow speed, with minimum use of the diving planes.
Compensation. Compensation is the process of transferring ballast, in the form of water, between the variable tanks, and between the variable tanks and sea, to effect the desired trim.
Main ballast tanks. Tanks that are provided primarily to furnish buoyancy, when the vessel is in surface condition and that are habitually carried completely filled when the vessel is submerged, except tanks whose main volume is above the surface waterline. are known as main ballast tanks.
Variable ballast tanks. Ballast tanks that are not habitually carried completely filled when submerged and whose contents may be varied to provide weight compensation are known as variable ballast tanks. Variable ballast tanks are constructed to withstand full sea pressure.
Negative tank. The negative tank is a variable ballast tank providing negative buoyancy and initial down-angle. Submarines normally will operate submerged in neutral buoyancy and without trim when the negative tank is nearly empty. It is used to reduce the time required in submerging from surface condition, to reduce the time required to increase depth while operating submerged, and to prevent broaching when decreasing depth. It may be blown or pumped.
Safety tank. The safety tank is a heavily reinforced main ballast tank arranged to permit pumping as well as quick blowing to regain positive buoyancy. Under normal submerged conditions, the blowing or pumping of this tank will bring the conning tower above the surface.
Bow buoyancy tank The bow buoyancy tank is a free-flooding, vent-controlled tank with its main volume above the normal surface waterline. It is located in the extreme bow of the vessel and is formed of the plating of the superstructure. Its function is to provide reserve surface buoyancy, emergency positive buoyancy in the submerged condition, and to aid in surfacing.
Auxiliary tanks. The auxiliary tanks are variable ballast tanks located at or near the submerged center of buoyancy, and are used to vary the over-all trim of the boat.
Trim tanks. The trim tanks are the variable ballast tanks nearest the bow and stern of the boat and are used to provide fore-and-aft compensation.
Normal fuel oil tanks. Tanks designed solely for containing the engine fuel oil.
Fuel ballast tanks. The fuel ballast tanks are designed to be utilized as fuel oil tanks for increased operating range. When empty, they may be converted to main ballast tanks, providing additional freeboard and thereby increasing surface speed.
Expansion tank. The expansion tank, connected between the head box and the compensating water main, admits sea pressure to the fuel oil tanks. It receives any overflow from the fuel tanks resulting either from overfilling the fuel system or from temperature expansion. The bilges are pumped into this tank to prevent leaving an oil slick or polluting a harbor.
Collecting tank. The collecting tank, connected to the fuel oil tanks through the fuel transfer line, serves as a water and sediment trap for the fuel oil being transferred to the fuel pump.
Clean fuel oil tanks. The clean fuel oil tanks are storage tanks located within the pressure hull. They receive clean fuel oil from the purifiers and are the supply tanks from which the engines receive their clean fuel.
Poppet valve drain tank. The poppet valve drain tank is located under the platform deck of the torpedo room immediately below the breech of the torpedo tubes. The air and water from the poppet valves, incident to the firing of torpedoes, is discharged into this tank.
Fresh water tanks. The fresh water tanks contain potable water for drinking, cooking, and certain sanitary facilities.
Battery fresh water tanks. . The battery fresh water tanks are storage tanks for the distilled water used in watering the main storage batteries.
Sanitary tanks. The sanitary tanks receive and store the ship's sanitary drainage until conditions permit overboard discharge.
WRT tanks. The WRT, or water round torpedo, tanks are variable ballast tanks, located in the forward and after torpedo rooms, for flooding or draining the torpedo tubes.
Main vents. The main vents are valves operated hydraulically, or by hand, for venting the main ballast tanks when flooding. They are located in the top of the risers of the main ballast tanks.
Emergency vents. The emergency vents are stop valves in the vent risers near the tank tops and are used in case of damage to the main vents. They permit sealing the tank to prevent accidental flooding and also permit blowing the tank if desired.
Venting. Venting consists of permitting a flow of air into or out of a tank.
Riding the vents. Riding the vents is a surface condition in which the main ballast tanks are prevented from completely flooding by the closed main vents which prevent the escape of air.
Flood valves. Flood valves are hinged covers at the bottom of certain ballast tanks which may be opened to admit or expel sea water.
Flooding. Filling a tank through flood ports, open flood valves, or other sea connections, is known as flooding.
Blowing. Blowing a tank consists of expelling its contents by compressed air.
Pumping. Pumping a tank consists of using a pump to transfer liquid from the tank to sea, from sea to tank, or from one tank to another. The tanks must be vented during this operation.
Bow planes. The bow planes are horizontal rudders, or diving planes, extending from each side of the submarine near the bow.
Stern planes. The stern planes are horizontal rudders, or diving planes, extending from each side of the submarine near the stern.
Two short blasts are sounded on the diving alarm, the second blast is
the signal to start the dive. An alternate signal is the word "Dive, Dive,"
passed orally. When the diving alarm is sounded, the following procedure
is followed (items marked with an asterisk are executed at once without further
GERMAN NAVAL POWER:
Admiral Erich Raeder: True to his Profession
By Michael Harris See this and other interesting historical articles on The Old Dominion University Historical Review (1994) Page published by Michael Hanley: http://www.odu.edu/~hanley/history1/COVER.htm
. . . the basic principles of the military services are unchangeable. Courage and candor, obedience and comradeship, love of fatherland and loyalty to the State: these are ever the distinguishing characteristics of the soldier and sailor. Building character through intelligent training and education is always the first and greatest goal. (59)
These words sum up the personal attitude and professional approach of the architect of the German Navy of the Second World War. Although he never personally commanded a warship,60 Grand Admiral Erich Raeder served on several cruisers and as Chief-of-Staff to Admiral Hipper saw intense action at the Battle of Jutland. Throughout his career Raeder remained the embodiment of the ideal Clausewitzian warrior. His concentration remained focused upon his duties as a military officer and he consistently resisted all attempts to be drawn into the political turmoil that marred the Weimar Republic. The role of the Navy always remained subservient to the demands placed upon it by the civilian government.
Raeder guided the rebuilding of the German Navy through the hazards of the Versailles restrictions and Nazi politics with the skill of an accomplished navigator. He remained true to his code as a professional warrior and when it became apparent that he could no longer serve Hitler as the Chief of the Admiralty because of their differences on how to conduct German naval warfare, he resigned. Although convicted as a war criminal at the Nurenburg Trials, (61) Raeder's conduct and professionalism as the Commander in Chief of the Navy were unimpeachable and later vindicated. (62)
Like most of the professional officer corps, Raeder had been greatly distressed by the terms of the Treaty of Versailles, (63) but accepted it and served as best he could in the positions he was assigned. His chance to actively change the dismal state of his beloved Navy came in 1922, when he was promoted to Rear Admiral as the Inspector of Naval Education. In this position he began a broad program that built up the professional and well-trained core of officers and petty-officers that accounted so well for themselves in the unequal naval duel of the Second World War.
As the basis for establishing his training programs, Raeder used the following guidelines:
. . . 1) Only through firm but friendly discipline can a crew be expected to achieve a high standard of efficiency; 2) The prerequisite for such a state of discipline is a well disciplined corps of officers and petty officers; and 3) A modest but definite feeling of pride and self-respect, commensurate with the officer's rank, must be instilled into the officer corps if it is to fulfill its duties. (64)
In addition to implementing these fundamentals which helped restore an esprit de corps, Raeder also addressed the curriculum of the various schools and sought to achieve a closer relationship between engineering officers and line officers. The specialty training for the petty officers and enlisted was of particular concern since there was a lack of both curriculum and teaching staff sufficient for meeting the challenges of a modern navy. Raeder also felt that there should be additional training available to prepare sailors for civilian life once their enlistment was up. He was sure that only by offering such a program to enable young men to prepare for future careers, could the Navy attract the caliber of recruits that it needed. (65) The result was a well educated and very loyal cadre of sailors.
In the winter of 1922-23, Raeder faced another academic challenge. The Treaty of Versailles had also abolished all of the staff colleges and there was no formalized training for the continued development of mid-level or senior officers. Using his old texts from courses he attended and personal notes on naval warfare and Admiralty staff duties, Raeder developed an officer training program. Initially designed as a two week "professional course," the program eventually grew, until in 1927 it was a year and a half in length. The program was never officially termed as a War College, but instead referred to as a "Course for Assistants to Commanding Officers." (66)
Raeder also took great pains to re-institute some of the traditions and customs of the old Imperial Navy when he was later assigned as Commander of the Naval District of the Baltic, especially those that promoted better relations between the Navy and the civilian community. The old Naval Regatta Club in Kiel was reopened, providing a training function for the German Navy as well as sponsoring several German sailing enthusiasts in international competition. The Navy Wives Society was revived and helped to weave a tighter feeling of community within navy families. Under his leadership, the port of Kiel began to host a number of foreign warships and even a no-notice visit by the King of Spain in September, 1928. (67) Raeder had accomplished a significant amount in the internal reorganization of the Navy and its resurgence as a military entity.
In the latter part of 1928, following the resignation of Admiral Zenker over a financial scandal, Raeder was appointed as Chief of the Admiralty after two days of close questioning by Defense Minister Groener. Raeder's plan for running the Admiralty had been acceptable. He would have unrestricted control over naval operations, direct access to the Minister of Defense to discuss all naval matters, and complete independence of the Navy from the Army High Command. This independence ensured that the Navy was not tied to Army finances or politics, and remained under the command of a single Admiral instead of a staff arrangement like that of the Army.
At the time when he took command of the Navy, several initiatives were underway for which Raeder was now responsible. For several years the Navy had been expanding and by 1926, a number of secret contracts had been established in various countries for the study and construction of forbidden weapons: airplanes, small torpedo boats, and submarines.68 Plans for the German Navy to be more than a navy limited to the Baltic or coastal patrols began to develop, including the development of the
pocket battleship Deutschland. (69) This initiative was in response to both the perceived threat of a Polish invasion of East Prussia and Danzig, with the French as potential Polish allies, and the growing realization of self-worth within the German Navy. Raeder described this awareness as the Navy "acquiring character." (70) By the end of 1929, Admiral Raeder announced to his senior command and staff officers that after careful study he was convinced of the vital importance of the North Sea to Germany. (71) German naval officers as a whole began to look at the high seas and the future role that the German Navy must play upon that great expanse.
During the crisis years of Hitler's ascendancy, first as Chancellor and then as Dictator, Raeder was able to keep the Navy on the periphery of the chaos and out of politics. (72) While the Nazi extremism was abhorrent to Raeder and most of the officer corps, the more aggressive and nationalistic policies of the new regime did sponsor the more rapid growth of the Navy and offered freedom from the restraints of the Versailles Treaty. These restraints were tested time and time again, such as when loopholes were exploited for the construction of the battlecruisers Scharnhorst and Gneisenau in 1934. (73) Following the 1935 Anglo-German naval agreement, in which Germany agreed to never exceed one-third of the British surface fleet and sixty percent of the British submarine force, the super-battleships Bismarck and Tirpitz were laid down in 1936, (74) thus continuing Germany's naval expansion.
As the Navy expanded, Raeder grew more concerned as to its potential adversaries. Previously most battle plans had been devised against the French and Poles. Even the Russians had been included in the German plans. Raeder feared that Hitler's political ambitions, would eventually bring Germany into conflict with England, the premier naval power, despite Hitler's earlier assurances to the contrary. (75) By May 1938 the topic of a potential future war with England was discussed openly in Berlin. In January 1939, Raeder devised the "Z Plan" by which Germany would achieve a "balanced fleet" by 1948. (76) While Hitler wanted a fleet sooner, he assured Raeder that there would be no need for a fleet until 1944 at the earliest. (77) Unfortunately for Raeder's long range plans, Hitler's time-table did not remain as promised and war broke out with England in 1939.
Once hostilities began, Raeder made his plans on how to deal with the English superiority on the seas. Meeting the British fleet head on and hoping to achieve victory with a decisive sea battle was out of the question. Germany lacked the number of ships to engage in such a strategy. Raeder was convinced that to defeat the British, the primary objective should be England's lifeline of commerce. (78) To accomplish this goal, Raeder planned to attack Britain's overseas trade with groups of battleships and cruisers as well as U-boats and auxiliary raiders. (79)
The diverse threat of these naval units would split and divide British resources. The faster speed of German pocket battleships and cruisers would allow them to fall on lighter Royal Navy units, or escape the heavier and slower British battleships. The German battleships, with their greater speed and range of action, could back up the other German units as needed and were powerful enough to match any battleship the British possessed. The invisibility and constant menace of the U-boat wolf packs served to stretch the Royal Navy far and wide, making the forays of the cruisers and battleships easier and more dangerous to British shipping.
As aggressively as he tried to pursue the offensive at sea, Raeder was equally concerned with the defense of the Baltic, especially with regard to the neutral states of Norway and Sweden. Sweden provided Germany with greatly needed iron ore and Norway provided a safe northern route for German ships to enter the Atlantic from the North Sea. But Raeder was concerned with how long their neutrality would last.
Extensive intelligence reports indicated that the British were intending to land troops in Norway and cut off the northern route to the Atlantic. (80) Plans were conceived for the occupation of Norway as the only way to be sure that England was not able to effectively close up the Baltic. (81) The seizure of the German supply ship Altmark by the British destroyer Cossack while in Norwegian waters and under escort by Norwegian patrol craft, convinced Raeder that Norwegian neutrality was a moot point to the English. Something had to be done to secure German access to the North Sea. The German invasion of Norway commenced on April 9, 1940. (82) The occupation of Norway, with its several North Sea ports, presented the Royal Navy with an even harder task of containing the German surface fleet and no chance of blocking the U-boats from reaching the Atlantic.
The next great challenge for Raeder was the impending plan for invading England. Raeder foresaw numerous difficulties in the endeavor. The transports used so successfully in Norway were not designed to handle the long trip across the Channel. The skies had to be controlled by German air power and Goring was showing increased signs of preferring to attack London instead of the RAF. (83) The Royal Navy would have to be dealt with as well. Although the German occupation of Norway had been inconvenient to the British, invading English soil would be vigorously resisted with the full force of the Royal Navy. (84) Therefore, as many units that could be destroyed in advance had to be accomplished or risk facing them during the invasion. Raeder argued against the invasion plan because of the severe difficulties involved and eventually the impetus for the idea faded. But the time and effort had robbed precious resources from what he felt was the only way to defeat England - attacking its commerce.
Raeder also argued against Hitler's next great venture, the invasion of Russia. Opening a second front made no sense, not with England still undefeated. Raeder offered the Mediterranean as an optional field of operation instead. The Italians had not fared well against the British, and Raeder was convinced that threatening or even capturing the Suez Canal would be a grievous blow to the English. Hitler's plans for Operation Barbarossa were delayed only briefly despite all the facts and figures Raeder presented.
The final break with Hitler and Raeder's resignation from the post of Chief of the Navy came in December 1942. A German naval task force had gone out to intercept an Allied convoy attempting the dangerous Murmansk run with a strong cruiser and destroyer escort. The Germans made initial contact, inflicted severe damage on the escorts and sustained only moderate damage to the task force. The convoy, however, escaped under cover of night since the German commander would not risk a night action where the darkness gave a significant advantage to the torpedoes of the British destroyers. Hitler was furious as he had expected a repeat of a similar situation in March of 1942, where 22 of 33 convoy ships had been sank. He vented his frustration on Raeder, who promptly resigned after 10 years as head of the Navy.
Grand Admiral Raeder was not an innovative genius or brilliant strategist. His contribution lay in his talent as a leader and shaper of the Navy. He understood sailors and what it took to enable them to do their job at sea. Training and discipline provided the framework for developing a skilled naval fighting force. Raeder firmly believed in a focused chain of command and trusting decisions made by the commander on the scene. Raeder realized the critical importance of seapower and lamented the inability of German leaders to learn from the lessons of World War I, where Germany was brought to its knees by the pressure of naval blockade. (85) This was the strategy he tried to bring to bear on England, but was unable. He discussed, debated and argued with Hitler regarding the Navy's role in the war but, when ordered, accomplished his orders to the best of his abilities in the manner of a true professional.
Old Dominion University Historical Review
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