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Torpedo Attack Procedures

SOME EQUIPMENT:

DRT: (Dead Reckoning Tracer)  This is a glass top desk usually found in the after starboard side of the conning tower. It has only two inputs. The submarine course and the submarine speed.  It shines a light up through the glass table top and through a sheet of paper used to track the target.

TBT: (Target Bearing Transmitter) This is a waterproof set of binoculars mounted on the bridge.  When you look through it at a target, the bearing can be transmitted to the TDC in the conning tower.

PERISCOPES: Number 1 is the approach scope.  It breaks the surface at 62' 5".  It also contains ST radar. I am a little fuzzy on how this works, but it could get a range to the target. Number 2 is the attack scope and breaks the surface at 67' 5".   Both have horizontal lines in them where if you have an estimate of the target masthead height, you can count the number of horizontal lines it crosses and get a rough idea of the target range.   #2 also has what is called a stadimeter, much like what is used on surface ships, where you match up two images and get a range estimate.  TDC: (Torpedo Data Computer) usually located in after end of conning tower on port side.  It has automatic input of the submarine course and speed.  All other  inputs are introduced manually (if I remember correctly !) It also has a section for the target.

CONTACT PHASE: Basic object is to expeditiously determine the relative movement of the target. This phase commences with the first indication of an enemy target in the vicinity, either by radar, visual, or sound. The duration of this phase is the period from the initial contact until the approach phase commences.

APPROACH PHASE; The approach phase commences when the submarine maneuvers to put it directly ahead of the target at a range that will allow time for maneuvering to a favorable firing position during the attack phase. The object of this phase is to aggressively and tenaciously close the enemy to a favorable position for the attack. During this phase there is opportunity to determine the type of target. its tactics, its escorts, its course and speed, and any other data necessary for a successful attack. Among the many items that can be observed are: Sea state & direction, Visibility, Cloud cover, Wind, Sun or Moon direction, Any aircraft, Number of targets, Target classification, Hull number & name, Flags flying, Guns, Radars, Riding high or low, Deck cargo, People on deck, any special rig, Light burning, Length, Mast height. Number of decks, Bow wave, Color, Smoking stacks., etc, etc

ATTACK PHASE: When the submarine has closed the target sufficiently to maneuver into a favorable attack position, the attack phase commences. The most favorable position is determined at the beginning of the phase from all the data available and from the circumstances dictated by the approach phase. Attack must be pressed home as long as opportunities are presented and the phase is ended only when the submarine commences maneuvering to evade. The object of this phase is to sink the target.

PROCEDURES DURING THE APPROACH AND ATTACK; Using the TBT, Radar, Periscopes, Sonar, the bearing of the target is fed into the TDC. When ranges are obtained or estimated, this is manually cranked into the TDC. When target course is estimated, using angle on the bow, this is manually cranked into TDC. An estimate of target speed (sometimes using sonar shaft turn count) is manually cranked into TDC. Now the TDC operator has the following: Submarine course and speed, Target bearing, range, course and speed. At the same time the DRT operator is plotting the target bearing and range on the track sheet from the little light that is keeping track of the submarine course and speed. All of this is just the initial estimate. When periscope observations are made, the approach officer should be made aware of the submarine speed, and depth, so as to minimize the feather of a wake made by the scope He should also be made aware of the time elapsed since the last observations, as this may give some indication of whether or not the target is on a zig zag plan and changing course about every six minutes. The TDC operator should also announce what the generated bearing of the target is so the periscope can be placed on the target immediately. Periscope observations should be of only a few seconds duration. The primary purpose of each periscope observation is to determine the target bearing (this is accurate and automatically transmitted to the TDC), the angle on the bow, ie: the target course , and the target range (described above). The range is an estimate, but can be refined by using ST radar. There are a whole list of other information about the target that can be observed and used to identify the target, etc. (See above Approach phase where I listed some items). The TDC operator knows what the target generated bearing, range, and course should be, IF the previous inputs to the TDC are completely accurate. When the new information from the scope observation is compared to what the TDC is generating, then some refinement is made to target course and speed. At the same time, the DRT operator is plotting the new bearing and range from the latest observation and getting his best estimate of target course and speed. . If the approach officer announces an angle on the bow (ie: the target course) that is significantly different from what the TDC is generating, then the TDC operator should tell the approach officer that it appears the target has zigged or changed course. As the attack phase gets closer to the target, the approach officer will usually shift to using # 2 scope and lower the submarine depth accordingly. The #2 scope has a much smaller head and makes a much smaller feather wake. When all members of the approach party are in substantial agreement as to target bearing (not much disagreement here), range, speed, and course, the best estimates are put into the TDC. When the approach officer believes he is in the best position to fire, he announces "Final Bearing and Shoot" (notice he does not say the word "fire"). When the scope goes up and it appears that all the generated information in the TDC is correct, he announces "Bearing Mark". No other input is normally needed at this point. If the approach officer notices there is some significant difference in the data, he will so announce that and the situation will change and new data can be entered in the TDC. On matching up the input of the bearing into the TDC the TDC takes all of the above information, plus the speed of the torpedo and generates a torpedo gyro setting for either the Forward Tubes or the After Tubes. This gyro setting is automatically transmitted to the Torpedo room and goes into the Torpedo. The Mark 14 torpedo can be fired with a gyro angle of up to 160 degrees right or left, however, this large angle introduces a very large margin of error and is called curved fire. It is best to try to keep the torpedo gyro angle to less than 30 degrees.. After all inputs are generated in the TDC the word goes out "Fire One" (etc, etc, etc). Hopefully the Torpedo Room will announce "Number One fired electrically" ! The above firing procedure is for firing one torpedo at the MOT (Middle of Target). If multiple torpedoes are to be fired, there are several formulas and procedures for spreading the torpedoes along the length of the target. On multiple firings, there is usually a spread that covers more than 100% of the target length, so if there is some error in the generated target data, there is more chance that some of the torpedoes will hit.

Courtesy of Bob Thomas (USS Carp).

The torpedoes used by the USS Bergall during the war were:

Mk 14 (-3A)        DEVELOPMENT DATE:        1931        APPROXIMATE IN-SERVICE DATES:    1938

Torpedo Mk 14, developed as a replacement for the Mk 10 torpedo had a longer range than the Mk 10 and had a 100-pound heavier warhead charge. This torpedo was the primary submarine-launched, antisurface ship torpedo used in World War II until the introduction of the electric Torpedo Mk 18. Approximately 4,000,000 tons of Japanese shipping were sunk by the Mk 14 torpedo. Originally introduced for use as mechanically-set torpedo, the Mk 14 was modified for use with modern fire control systems (and designated Mod 5). This torpedo is still in service use. Torpedo Mk 14 was developed by the Naval Torpedo Station, Newport, R.I. and approximately 13,000 were produced during the second World War by the Naval Torpedo Stations in Newport; Alexandria, Va.; and Keyport, Wash.; and the Naval Ordnance Plant, Forest Park, Ill.

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Mk 18 (-1)        DEVELOPMENT DATE:    1943        APPROXIMATE IN-SERVICE DATES:    1943-1950

Torpedo Mk 18, a submarine-launched, antisurface ship weapon, was one of the most successful torpedoes of World War II. This torpedo, based on a captured G7e German torpedo, was widely used in the latter stages of the war. Torpedo Mk 18 was developed by the Westinghouse Electric Corp., Sharon, Pa., and the Electric Storage Battery Co., Philadelphia, Pa., and approximately 9000 were produced by Westinghouse and the Naval Ordnance Plant, Forest Park, Ill. In 1944, 30 percent of the torpedoes fired from submarines were Mk 18 torpedoes, while in 1945, it was 65 percent. The tactical advantage of Torpedo Mk 18 was the lack of a wake. About 1,000,000 tons of Japanese shipping were sunk by the Mk 18 torpedo.

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Mk 23        DEVELOPMENT DATE:        1943        APPROXIMATE IN-SERVICE DATES:    1943-1946

Torpedo Mk 23 was developed to satisfy what appeared to be a valid tactical requirement of World War II: the high-speed feature of the Mk 14 torpedo. In the early stages of the war, the low-speed feature (31 knots - 9000 yards) of the Mk 14 was rarely used. Due to the changing requirements of the war, however, most of the 9600 Mk 23 torpedoes saw little service. In the latter stages of the second World War, fewer targets and better/smarter escorts/escort tactics necessitated firing from longer ranges.   The Mk 14 torpedo, with its low power and longer range, became the preferred weapon. Much of the Mk 23 inventory was scrapped or converted to Torpedoes Mk 14 while other units were cannibalized for spare parts. This submarine-launched, antisurface ship torpedo was developed by the Naval Torpedo Station, Newport, R.I., and produced by the Naval Torpedo Stations at Newport; Alexandria, Va.; and Keyport, Wash.; and by the Naval Ordnance Plant, St. Louis, Mo.

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Mk 27    Mod 0        DEVELOPMENT DATE:    1943        APPROXIMATE IN-SERVICE DATES:    1943-1946

Torpedo Mk 27 Mod 0, developed by Bell Telephone Laboratories, was an acoustically-controlled, submarine-launched, anti-escort ship weapon. Used during the second World War, the torpedo had a single propeller driven by an electric motor. This torpedo was essentially a Mine Mk 24 modified for submarine launching in a 21-inch submerged torpedo tube by the addition of wood guides on the outer cylinder shell. Approximately 1000 units were produced by the Western Electric Corp., Kearney, N.J.

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