Baffles (submarine)

The baffles is the area in the water directly behind a submarine or ship through which a hull-mounted sonar cannot hear. This blind spot is caused by the need to insulate the sonar array, commonly mounted near the bow, from the noise of the vessel's machinery.

During the Cold War, one submarine would frequently attempt to follow another by hiding in its baffles. This led to the practice of "clearing the baffles", that is, turning to observe the blind spot and detect any followers. Related maneuvers included the "Crazy Ivan", a hard turn to clear the baffles and position the submarine to attack any followers, and "Angles and Dangles", a five-hour process of rapid direction and speed changes to ensure that all items aboard were properly secured for hard maneuvering and would not fall or shift suddenly, producing noise that the enemy could detect. The baffles-clearing maneuvers undertaken by Soviet Yankee-class submarines were dubbed "Yankee Doodles."

Hiding in a sub's baffles is dangerous because of the risk of collision. Such tactics have fallen out of use since the advent of the towed-array sonar, which negates the baffles' blind spot.

Since a sonar array is extremely sensitive to underwater sounds, it must be protected from the noise generated by machinery on the vessel on which the sonar is installed. Otherwise, its own noise would tend to drown out other sonar targets. To reduce noise, sound-attenuating material is placed between the sonar and the rest of the vessel. This makes the sonar much more effective, but causes a blind spot where this material is: as most hull-mounted sonars are located at the front of the vessel, the resulting blind spot is located directly behind the vessel.

The term baffles is likely derived from a lesser used definition of the word itself, that of "a partition that prevents interference between sound waves in a loudspeaker." In the instance of its usage in terminology pertaining to submarines, the definition can be expanded and slightly modified to, "an area behind the submarine that due to the cavitation and the wake left by the propulsion system impedes the ability for on-board sonar systems to accurately establish what, if anything, is behind the submarine."

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