Magnetic Silencing Facility Provides Unique Service

Story Number: NNS100224-11Release Date: 2/24/2010 5:02:00 PM
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By Bill Mayo, Trident Refit Facility, Kings Bay Public Affairs

KINGS BAY, Ga. (NNS) -- One of America's newer fast attack submarines, USS Toledo (SSN 769), visited at the Trident Refit Facility Kings Bay, Ga., Magnetic Silencing Facility (MSF) Feb. 5.

MSF Kings Bay is considered a model for the rest of the Navy, and is being modernized so the facility will be able to treat all types of submarines, as well as prepare for the delivery of future submarine classes.

Software and procedures being tested and developed at MSF Kings Bay will be rolled into future facilities in other parts of the country and retro-fitted at existing facilities as well, greatly reducing the time and expense for needed upgrades. Toledo's visit to Kings Bay provided a unique opportunity to collect valuable data for this development, and allowed the ship to return to sea after a minimal amount of time in a greatly improved magnetic condition.

Due to magnetic fields that are constantly being encountered during normal ship operations, ships and submarines build up a magnetic signature. The earth's natural magnetic fields between the North and South poles are being crossed routinely while the vessels are underway. The traversing of these natural fields, and vessels lying dormant for extended periods of time during scheduled maintenance, result in changes to a vessel's magnetic signature. Correcting those changes requires a thorough treatment process to minimize the level of permanent magnetism.

The MSF treatment slip, recognized as a prominent fixture at the Kings Bay Naval Submarine Base, is the first structure seen as vessels arrive, via the Inter-coastal Waterway. It is unique in design and generates much discussion when viewed for the first time.

Placed in service in 1994, it is known as a "drive-in" facility, a recent development in the arena of magnetic treatment facilities. All that is required of its visitors is to merely drive in for a treatment. No other action is required of ship's complement to prepare for treatment except safeguarding of fragile equipment that may be affected by magnetic fields.

Other treatment facilities used by the Navy require hand-wrapping, in that the ship's company must assist the magnetic facility to wrap large electrical cables completely around the hull of the ship prior to commencing treatment. Depending on the size of the vessel, this can become a lengthy and labor intensive process.

The electrical cables at MSF Kings Bay are suspended permanently overhead as well as beneath the hull, requiring no additional cable handling. The process, known as flash deperming, is a calculated procedure where magnetic fields are generated by shore-based generation equipment and applied in a controlled manner to align the ferrous (contains iron) materials in the steel known as "domains" in a specific sequence that leaves the ship in a stable and predictable magnetic condition. With the increased efficiencies realized by the mooring processes and no hand-wrapping required after arrival, the time in the treatment slip can be optimized.

During World War II, the Germans introduced magnetic mines, an inexpensive and highly effective weapon, used to inflict heavy damage upon allied shipping. These devices were tethered to an anchoring device, and were automatically triggered by ships as they passed overhead by the retained magnetism present in their hulls. The process of deperming greatly diminished losses of shipping as the war progressed.

As technology advanced, aircraft were retrofitted with detection capabilities that exploited the magnetic properties of ships. The process of reducing magnetic signatures of vessels is as important today as it was 70 years ago, due to significant advances in technology and the increased lethality of delivery devices.

For more news from Trident Refit Facility, Kings Bay, visit

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