Wake homing

[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.

This will eventually bring it to the stern of the ship, where its warhead can do the most damage to propulsion and steering.

In 2013, the US Navy tested prototypes of a system known as the Countermeasure Anti-Torpedo (CAT),[2] which had been designed to intercept and destroy the incoming torpedo.

Refractometric detection senses minute changes in the water's refraction index due to cavitation bubbles and such.