Luftaufnahme Nordrhein-Westfalen (F 223) mit Kielwasser

Wake homing is a

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, ...

guidance technique based on the wake trajectory left behind a moving target. The torpedo is fired to cross behind the stern of the target

ship A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished ...

, through the wake. As it does so, it uses

sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on o ...

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 The stern is the back or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite the bow, the foremost part of a ship. Or ...

of the ship, where its

warhead A warhead is the forward section of a device that contains the explosive agent or toxic (biological, chemical, or nuclear) material that is delivered by a missile, rocket, torpedo, or bomb. Classification Types of warheads include: * Expl ...

can do the most damage to propulsion and steering.

Advantages and disadvantages

The system is difficult to jam, but it can be distracted by other ships crossing the wake. In 2013, the

US Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

tested prototypes of a system known as the Countermeasure Anti-Torpedo (CAT), which had been designed to intercept and destroy the incoming torpedo. Deployment of the system did not proceed as planned due to performance issues. The main disadvantage of wake homing is that the course taken to the target is not direct and may be far from optimal, as it mimics the target's own trajectory from the point of wake's interception onward. As the torpedo's remaining distance always increases hand-in-hand with the distance made by the vessel itself, this necessitates the torpedoes to have a significantly higher speed and longer range than normal. Also, being an active method, sonar wake homing gives up the torpedo position. This is why it is usually supplemented by passive methods, such as

thermal A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example ...

and refractometric wake detection. Thermal wake detection centers on locating changes in water temperature in the ship's wake. Refractometric detection senses minute changes in the water's

refraction index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

due to

cavitation Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, ca ...

bubbles and such.

Examples

* Type 53-65 (and later 53-65K and 53-65KE/TT-3) — the first mass-produced wake homing Soviet torpedo; in use with some operators of the Soviet Kilo-class submarines such as , , or . * Type 65 — Soviet torpedo of the '70s. * Yu-6 — Chinese heavyweight torpedo in service since 2015; also operated by the

Indian Navy The Indian Navy is the maritime branch of the Indian Armed Forces. The President of India is the Supreme Commander of the Indian Navy. The Chief of Naval Staff, a four-star admiral, commands the navy. As a blue-water navy, it operates si ...

. * CHT-02D — North Korean torpedo claimed to have a wake homing capability. * DM2A4 Seehecht (export designation "''SeaHake mod 4''") — modern German heavyweight torpedo. * Roketsan Akya — modern Turkish heavyweight torpedo.

References

Weapon guidance {{Missile-stub