Crazy Ivan

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Example diagram of the baffles of a submarine, showing the directional arc behind a submarine where the sub's sonar is nearly ineffective.

Crazy Ivan is a Naval term for a submarine maneuver, characterized by any number of sudden and sharp turns, used by submarine crews to "look behind" their boat using sonar.

[edit] Baffles

Because of the acoustic distortions and noise caused by propeller blades, it is nearly impossible for conventional sonar to detect objects directly behind a submarine. So, with sudden turns, the area where the sonar is not effective shifts relative to the current heading of the submarine, causing previous gaps in sonar coverage to be revealed while masking known areas. This gap in sonar coverage caused by the submarine's own propeller is commonly known amongst submariners as the "baffles".

[edit] Name and description

The "Crazy" part of the name comes from the fact that these maneuvers were very sudden and could lead a trailing submarine to collide with the submarine performing the maneuver and "Ivan" was a common nickname used to refer to the Russians during the Cold War.

A standard tactic of pursuing submarines used by the United States Navy and other Western navies during the Cold War would be to closely follow Soviet submarine and escaping detection by hiding in the baffles. Pursuing submarines using this tactic would be put in danger if a Soviet submarine cleared their baffles by performing a Crazy Ivan. The first was detection by the leading submarine, which was commonly avoided by stopping the engines and going to maximum silence. However, this led to the second danger — collision. With its momentum, the pursuing sub's forward movement would continue with the possibility of collision with the unknowing submarine dead ahead in the process of turning sharply.

An example of a similar maneuver, called "Angles and Dangles", gone wrong happened on June 20, 1970, when USS Tautog collided with a Soviet Echo class submarine known as "Black Lila". "Angles and Dangles" is a five-hour dance of random figure eights, sharp turns, and random depth changes. The maneuver is executed at the start of a voyage and its purpose is to find out what noise the submarine is making and if anything is stowed in the wrong place. The maneuver is similar to a Crazy Ivan although it lacks the latter's offensive fury and is a random execution of turns, unlike a Crazy Ivan. Both submarines survived the incident.

Most modern submarines deploy a towed array sonar which specifically covers the baffles, rendering the Crazy Ivan mostly obsolete.

[edit] References

• Sontag, Sherry; Drew, Christopher; Drew, Annette Lawrence (1998). Blind Man's Bluff: The Untold Story of American Submarine Espionage. Harper. ISBN 0-06-103004-X.
• Crazy Ivan: A True Story of Submarine Espionage by W. Craig Reed, William Reed, (ISBN 0-595-26506-5)

[edit] External links

• Submarines, Secrets, and Spies where the former commander of an American submarine is interviewed and the subject is mentioned.
• A Kursk web site mentioning the Crazy Ivan maneuver
• A description of the maneuver