Anti-submarine warfare is a tricky and often expensive issue. Becuase of the submarine's unique fighting style, there are very few weapons which could engage a submarine effectively.This is a general listing on the various approaches to anti-submarine warfare.
Possibly the least effective technique. Such a technique is largely ineffective for most encounters, and often the best thing to do is run and quit. Unless a submarine is surfaced or at an extremely shallow depth, such a technique should not even be considered.
Basic torpedoes are even less effective than guns, since basic torpedoes cannot hit submerged targets. However, the Underwater Torpedo Tube, when mounted on the hull of a warship, can be a lethal and effective antisubmarine weapon. Capable of engaging enemy submarines at their ranges without their speed handicap, these can be extremely effective. However, the added weight, unusual shape, high cost and limited utility in ship-ship combat makes this only useful to players who have personal grudges against submariners, those who encounter them too frequently and those who are constructing specialized submarine hunters.
Only dive bombers are of any good. Their large splash damage radius makes it useful against relatively shallow-diving submarines. If the submariner decides to dive deeper than the spash damage will hurt it, these types will be useful finding the precise location of a submarine. Otherwise, these should be left behind.
Specialized ASW Weapons
These were built to hunt down submarines. The two antisubmarine weapons are the Depth Charge and the Hedgehog. The Depth Charge, while only requiring resource to build, is not a particularly effective weapon, necessitating the attacking warshp to be nearly directly above the submarine to do damage. However, it is good just for the peace of mind of decent anti-submarine capability.
The Hedgehog is a far more effective weapon. Capable of stand-off ranges, it means that a submarine can be attacked with a slight amount of flexibility. It is extremely effective agianst submarines. Taking up the same area as a Depth Charge, the positions could be used interchangeably. However, its only weakness is its cost- three Rare Metal for a Hedgehog. However, if you desire for improved ASW capabilities, then this is a good investment.
The ideal approach against a submarine is from its sides- submarine torpedoes fire forward, mines are released behind a submarine and it also provides the biggest possible target to aim at.
Submarines can employ various methods to counter ASW weaponry. Deep diving will enable the submarine to evade aircraft damage and guns. Since most specialized ASW weapons involve coming very close to the submarine, a reasonably fast submarine can evade these weapons and their torpedoes will outrange them. A skilled submariner can lure opposing warships into a minefield. This will encourage new, aggressive players who just obtained ASW weapons into a lesson regarding mines.
A submariner who is able to identify the target's weapons can utilize low-space long-range high-powered weapons, notably the Mk 45 5 inch Gun, to destroy the targeted warship if the warship has weapons of inferior range.