Difference between revisions of "Degaussing"
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===Types of Degaussing=== | ===Types of Degaussing=== | ||
| − | The Forecastle permanent - Quarterdeck permanent coils (FP-QP) compensate for the longitudinal permanent component of the ship's magnetic field. The FP coil encircles approximately the forward 1/3 of the ship in the horizontal plane at the main deck. QP coil encircles approximately the after 1/3 of the ship in the horizontal plane at the quarterdeck. Any coil current changes require manual adjustment. | + | '''The Forecastle permanent - Quarterdeck permanent coils (FP-QP)''' compensate for the longitudinal permanent component of the ship's magnetic field. The FP coil encircles approximately the forward 1/3 of the ship in the horizontal plane at the main deck. QP coil encircles approximately the after 1/3 of the ship in the horizontal plane at the quarterdeck. Any coil current changes require manual adjustment. |
| − | The Forecastle induced - Quarterdeck induced coils (FI-QI) are located in the same area as the FP-QP coils, they compensate for the longitudinal induced component of the ship's magnetic field. The FI-QI current is proportional to the horizontal component of the Earth's magnetic field along the ship's longitudinal axis. The FI-QI coil current is manually changed, by shifting the "H zone" switch on the switchboard, when the ship's location changes H zones. The degaussing system automatically compensates for heading changes by converting a gyro input signal to a magnetic heading. | + | '''The Forecastle induced - Quarterdeck induced coils (FI-QI)''' are located in the same area as the FP-QP coils, they compensate for the longitudinal induced component of the ship's magnetic field. The FI-QI current is proportional to the horizontal component of the Earth's magnetic field along the ship's longitudinal axis. The FI-QI coil current is manually changed, by shifting the "H zone" switch on the switchboard, when the ship's location changes H zones. The degaussing system automatically compensates for heading changes by converting a gyro input signal to a magnetic heading. |
| − | The Athwartship coil (A) is installed in the vertical plane and extends from the keel to the main deck. It compensates the athwartship induced and athwartship's permanent components of the ship's magnetic field. The A coil current consists of permanent and induced components. | + | '''The Athwartship coil (A)''' is installed in the vertical plane and extends from the keel to the main deck. It compensates the athwartship induced and athwartship's permanent components of the ship's magnetic field. The A coil current consists of permanent and induced components. |
Source: [http://www.fas.org Federation of American Scientists] | Source: [http://www.fas.org Federation of American Scientists] | ||
[[Category:Naval Warfare Systems]] | [[Category:Naval Warfare Systems]] | ||
Revision as of 14:19, 7 October 2004
In Brief
A steel hulled ship forms a massive magnetic field, adding or subtracting to the Earth's own magnetic field as it moves. Magnetically triggered mines and explosives use this field to detonate. Therefore, ships can be designed to negate this field, or to "hide" inside the normal magnetic field.
The ship's permanent magnetization is the source of the ship's permanent magnetic field. The process of building a ship in the Earth's magnetic field develops a certain amount of permanent magnetism in the ship. The ship's induced magnetization depends on the strength of the Earth's magnetic field and on the heading of the ship with respect to the inducing field (Earth's).
There are several different types of degaussing systems in fleets today. The basic differences between them can be characterized as to what type of power supply they use, and what type of control circuitry they use. For example, some units use silicon-controlled rectifier solid-state power supplies (as in the SSM system). Other systems use motor generator sets (as in the RM-5 type systems), and still others use a mixture of the two (as in the GM-1A units).
The Main coil (M) compensates the induced and permanent vertical components of the ship's magnetic field (Z zone). It is installed in the horizontal plane at the waterline. As the ship changes hemispheres the coil current polarity must be manually adjusted.
Types of Degaussing
The Forecastle permanent - Quarterdeck permanent coils (FP-QP) compensate for the longitudinal permanent component of the ship's magnetic field. The FP coil encircles approximately the forward 1/3 of the ship in the horizontal plane at the main deck. QP coil encircles approximately the after 1/3 of the ship in the horizontal plane at the quarterdeck. Any coil current changes require manual adjustment.
The Forecastle induced - Quarterdeck induced coils (FI-QI) are located in the same area as the FP-QP coils, they compensate for the longitudinal induced component of the ship's magnetic field. The FI-QI current is proportional to the horizontal component of the Earth's magnetic field along the ship's longitudinal axis. The FI-QI coil current is manually changed, by shifting the "H zone" switch on the switchboard, when the ship's location changes H zones. The degaussing system automatically compensates for heading changes by converting a gyro input signal to a magnetic heading.
The Athwartship coil (A) is installed in the vertical plane and extends from the keel to the main deck. It compensates the athwartship induced and athwartship's permanent components of the ship's magnetic field. The A coil current consists of permanent and induced components.
