Wake homing

Wake homing is a torpedo guidance technique based on the wake trajectory left behind a moving target.^[1]

The torpedo is fired to cross behind the stern of the target ship, through the wake. As it does so, it uses sonar to look for changes in the water caused by the passage of the ship, such as small air bubbles. When these are detected, the torpedo turns toward the ship. It then follows a zig-zag course, turning when it detects the outer edge of the wake, to keep itself in the wake while moving forward. This will eventually bring it to the stern of the ship, where its warhead can do the most damage to propulsion and steering.