[Krupp]

Originally Posted by hmatthias

OK, I know the German deck gun tactic was to only use it on crippled ships, to "finish them off'", and eventually they stopped using the deck gun altogether. What is the US tactic? For example, I am stalking a smallish costal merchant near the Japanese coast. Should I surface and hit him with the guns, since he is smaller, or will he call for help and I will get tons of planes/patrol ships/etc. after me? Just wondering how often the gun was used, as it seems like it was used more by the US then their German counterparts

1. Unless the submarine is unable to dive, combatant ships should not be engaged by gunfire, except they be of the small patrol type (more dangerous because of their depth charges than because of their guns), definitely preventing the accomplishment of a vital mission. In the latter case, the probable chance and relative advantage of possible destruction of the patrol vessel must be weighed against the disclosure of the submarine's presence or position, and the probable damage that may be received. Gun attacks on important merchant vessels will normally not be made, as the submarine will usually find itself out-gunned and at a disadvantage. When engaging surface targets, endeavor to do so as a surprise and from a position that will be poorly protected by lookouts and where the minimum number of enemy guns can bear. Engage on bearings that will permit the best service to own guns.
2. Conditions of Readiness. Main Battery. Keep telescopes installed at all times and guns boresighted for long range. Keep ammunition in magazine, but be prepared, when action is imminent, to advance ammunition as near gun(s) as permitted by readiness to dive without delay. In order to be prepared for surprise night gun attack, set deflection scale to compensate for drift and set range scale between 2,000 and 4,000 yards.
3. In establishing and maintaining hitting range and deflection, use the simplest effective control methods against both aerial and surface targets.
4. Against surface targets use ranging shots, spread in range, to establish hitting gun range. Maintain hitting gun range by spotting methods that cross and recross the target and that depend only on the determination of whether shots are short or over (in range).
5. In general, procedure for submarine gunfire is very similar to local control of a single gun, or of local group control in the case of two-gun submarines, as on surface ships. The spotter and control officer are usually combined and communication with the battery should be as simple as possible. Absence of instruments and assistants, plus low spotting heights, complicate this problem.
6. Considering the type of target against which a submarine may expect to effectively use its gun, ammunition supplied will normally be common and high capacity point detonating in such proportions as is found to be most useful from time to time. The high capacity point detonating projectile and fuse have been found effective against steel plating as follows:
   • 3" up to 1" thickness
     4" up to 11/2" thickness
     5" up to 2" thickness
     6" up to 21/4" thickness