Torpedo Data Computer

The torpedo data computer (TDC for short) is located towards the front of the conning tower. It is used calculate the torpedo solution based on target motion analysis data gathered by the player, as well as control the firing of the torpedoes. The TDC has a number of dials, many of which can be set by the player directly, but also some that are calculated from the player inputs.

(1) Impact angle shows at what angle the torpedo is expected to hit the target. 0 means the target will be hit directly from behind, 180 directly from the front. The green and red zones denote starboard and port respectively. New players often mistakenly assume that the gauge represents a top down view of the target, with the bow pointing up, and the needle pointing where the torpedo will come from. This is not the case. It is usually desirable to have impact angles close to 90 degrees as that presents the largest target.

(2) Target speed must be set by the player. This is possibly the most critical setting to get right for typical torpedo attacks. For impact angles close to 90 degrees this setting demands very high accuracy, however for impact angles close to 0 or 180 it is much less important. Therefore it might be advisable to aim for impact angles away from 90 degrees if there is significant uncertainty with regards to the target speed.

(3) Torpedo Depth must be set by the player. This setting is not very critical, as long as it is not set so deep as to go underneath the intended target. It is however desirable to use a larger depth, as that will cause ships to sink faster when hit.

(4) The torpedo status panel shows the status of each tube, as well as the number of torpedoes left. The upper row represents the forward tubes and the lower row the rear tube. A lit bulb indicates that the tube is ready to fire, while a unlit bulb may be empty or in the process of being reloaded. The digital counter shows the total number of torpedoes left in the boat for the forward and aft tubes. In this case tubes I and IV have just been fired, however the screenshot was taken in the tutorial mission, and therefore the torpedo counter still shows all 12 forward torpedoes available.

(5) The angle tracking device can be set by the player. This can be used to slave the bearing input to either the observation periscope (O.P.), attack periscope (A.P.) or UZO, or not slaved (off). In the slaved modes the crosshairs in the appropriate device will be used to select the bearing to target. In the off position the bearing dials (10) on the TDC are used.

(6) Error light. This light will light up when the TDC is unable to find a valid solution. This is usually either due to too large of a gyro angle or to long of a range for the torpedo.

(7) The range dial must be set by the player. This dial denotes the estimated range to the target. It is required for three purposes. Number one is to calculate the time to impact, number two is to calculate the spread angle (13) and number tree is to compensate for parallax error. Parallax error correction is needed because the torpedoes are not shot out of the periscopes, but rather the bow or stern tubes, in a straight ahead or astern direction, after which they travel straight for a short distance before they start turning towards the target. If the torpedo has to make a considerable turn towards the target, that means it will be approaching from quite a different angle than what is observed from the periscope. This is especially true at short range. Therefore it is very important to be accurate with the range when shooting at large gyro angles (8) and short ranges. When shooting at longer ranges or small gyro angles even a very rough range estimate is good enough to hit the target.

(8) Gyro angle is the amount that the torpedo needs to turn after leaving the torpedo tube. It has two dials, the right dial is a course dial with graduations every 10 degrees, while the left dial is a fine dial, and will make a full rotation every 10 degrees, in a similar manner to the minute hand on a clock makes a full revolution every hour. Note that the aft tube leaves the boat at a gyro angle of 180 degrees, while the forward tubes leave at a gyro angle of 0 degrees.

(9) This switch allows the player to select any single tube to be fired, or to fire a salvo, in which case the salvo switch (15) will determine which tubes are used.

(10) The bearing dial can either be controlled directly by the player or slaved using the angle tracking switch (5). It will show which bearing to the target is to be used when calculating the torpedo solution.

(11) The angle on bow (AOB for short) dial must be set by the player. This dial must be set to the bearing to the U-boat as seen from the target. The dial is coupled with the gyro compass, and will take into account course changes from the U-boat. It is also coupled to the target bearing. These two coupling mean that when targeting ships in a convoy, where all ships hold the same course, the AOB dial needs only be set for a single ship, and the TDC will update it as the player shifts to different targets within the convoy. Only when the ships in the convoy change course is it necessary to re-adjust the AOB. When shooting at AOB close to 90 degrees, the AOB need not be very accurate to hit the target, however at AOB close to 0 or 180 it becomes very important that AOB is accurate. Consequently it is desirable to shoot at AOB close to 90. This also happens to coincide with Impact angle (1) close to 90.

(12) Target length can be set by the player. This setting is only used to calculate the spread angle (13) when firing a spread of torpedoes. It is therefore not important to set this to anything in particular when firing single torpedoes. It is however good practice to preset it to a typical ship size, so that it is already set if you need to fire off a salvo in a hurry.

(13) The spread angle displays the calculated spread angle between the torpedoes.

(14) This displays the estimated time to impact for the given TDC settings. It is good practice to start a stopwatch whenever a torpedo is fired, and take note of the estimated time to impact. That way you can tell whether a torpedo missed, as well as how well you did on your distance estimation. Experienced players will also take advantage of this in order to arrange near simultaneous hits of multiple torpedoes.

(15) The salvo switch can be set by the player to select a number of different tube combinations for salvoes. Take note though, that not all tube combinations are available, therefore it is a good idea to plan a head when combinations of single torpedoes and salvoes are to be used in rapid succession.