Mk.2/3/4 Countermeasure

This is a family of generic decoys, which are designed to spoof or decoy incoming enemy torpedoes. While the details of decoy design are closely held, it is assumed that they use several known methods for confusing torpedo guidance systems. One type uses chemicals to create a vast bubble field, the air/water interface of which creates a virtual "curtain" to a seeker head. Others uses microprocessor-controlled sound generators to draw the torpedo onto them, while the submarine has cleared the area. One other possibility is that they may emit a magnetic field designed to trigger the proximity detonator of the incoming weapon. Most modern submarines have at least two ejector tubes for such devices. For example, the Ohio-class (SSBN-726) has no less than eight launcher tubes for decoys.