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10 Cards in this Set
- Front
- Back
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purpose of degaussing
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Magnetic mines and torpedoes have a firing mechanism so constructed that they are actuated by a ship's magnetic field. Degaussing reduces the strength of this magnetic field. Consequently, some measure of protection against these weapons is afforded by degaussing. This is accomplished by using specific values of current through large cable loops to create a field equal and opposite to the pre-existing field to make the ship look magnetically invisible. There are two types of magnetism that affect the ship.
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TYPES OF MAGNETISM
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(1) Permanent - results from the ship being constructed of magnetic material.
(2) Induced - caused by the influence of the earths magnetic field upon the ship. |
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Degaussing control panel
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Located at load center 21 (lc21) it contains the switching and control circuits required for automatic and manual control of the degaussing current output of the "fl-ql", "fp-qp", and the "M" and "A" coil power supplies.
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Remote control panel
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Located in the chart house it contains circuitry necessary for monitoring the system operation and for the manually controlling the "FI-QI" and "A" coils from a location that is remote from the control panel.
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Power supply units
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Produces a reversible 5 VDC control signal for each coil channel control circuit.
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M coil
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The principle degaussing coil, called the main coil. It encircles the ship, inside the skin of the hull, in a horizontal plane approximately at the waterline. The M-coil compensates for the ship's vertical permanent and induced magnetism. The M-coil current is changed with changes in latitude.
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FP-QP coil
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Located at opposite ends of the ship in horizontal planes and are connected in series. The FP loop encircles the forward part of the ship and is just beneath the forecastle or uppermost deck. The QP loop encircles the after part of the ship and is located just beneath the main or uppermost deck. The QP and FP loops are connected in series with each other, and usually have polarities in opposite directions. This coil compensates for the ship's permanent magnetization. The FP-QP coil currents are changed when it is determined that a change occurred in the ship's permanent magnetism. This determination is made at a degaussing station.
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FI-QI coil
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Located same as the FP-QP coil. The FI-QI coils develop strong fields below the bow and stern of the ship, to neutralize (approximately) the induced longitudinal magnetism at these points. The FI-QI coil currents change with changes in heading and latitude.
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A coil (ATHWART SHIP)
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The "A" coils run perpendicular to the waterline. They are located in various locations. The "A" coil has loops in the vertical fore-and-aft planes. Its function is to produce a magnetic field that will counteract the magnetic field produced by the ship's athwart ship permanent and induced magnetization.
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L coil (LONGITUDINAL)
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Consists of loops in vertical planes, parallel to the frames of the ship. Always used when compensation for the pitch of the ship is required. It counteracts the magnetic field produced by the ships longitudinal permanent and induced magnetization.
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