testing magnets installed on epirb brackets

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Testing Magnets Installed on EPIRB Brackets

Prepared by Robert G. Garrott

CGD Five CFVS Coordinator

July 3, 2007

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Background Information 1

In 2006, CGD Seven CFVS Coordinator Larry Yarborough and SEC Charleston Lead Examiner Greg Johnson lead a detailed analysis of EPIRB false alerts. They found air and surface sorties triggered by false alerts cost the Coast Guard millions in fuel, personnel and maintenance expenses each year, and that there were two main causes for these false alerts.

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Background Information 2

Modern 406 MHz EPIRBs are designed to automatically activate if removed from their mounting bracket and in contact with water. To reduce false alerts, a magnet mounted in the bracket opens a magnetic reed switch in the EPIRB circuitry. The two most common problems causing false alerts are mounting the EPIRB in the bracket incorrectly, and for the magnet to be missing or out of position.

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Background Information 3

Because they can be placed in the bracket backwards (with the line spool facing out), ACR Satellite EPIRBs are more susceptible to incorrect mounting than other EPIRBs.

Careful attention to Owner’s Manuals and mounting diagrams can prevent false alerts due to incorrect mounting in the bracket.

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Testing for the Magnets

It takes just a few seconds to verify the magnet is properly installed in the bracket. The test device – an inexpensive magnetic compass. The bracket magnet will cause the compass needle to swing and point at the bracket instead of pointing at the magnetic north pole. The following slides show this occurring for several of the most frequently encountered marine EPIRBs.

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Category 1 ACR Satellite2 406 MHz

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Category 1 ACR Satellite2 406 MHz

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Category 2 ACR Satellite2 406 MHz

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Category 2 ACR Satellite2 406 MHz

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Category 1 McMurdo 406 GPS

Note: The magnet is positioned under the EPIRB and is not visible until the EPIRB is removed.

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Category 1 McMurdo 406 GPS

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Category 1 Pains Wessex 406 MHz

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Category 1 Pains Wessex 406 MHz

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Category 2 Pains Wessex 406 MHz

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Category 2 Pains Wessex 406 MHz

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Corrective Action

• Although magnets aren’t mentioned in the regulations, EPIRB design standards require this type of protective feature.

• If the bracket is damaged or the magnet is missing, the defective bracket is not in compliance with 46 CFR 25.26 and must be serviced by an approved EPIRB servicing facility.

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Examiner Action

• Advise the vessel operator that the bracket is defective. Possible negative outcomes:– Early replacement of discharged battery per 46 CFR

25.26-50(c)(1).– Government claims for reimbursing the cost of search

and rescue sorties.

• Issue a worklist item for timely servicing of the defective bracket and follow up.

• Worst case: Request Sector use COTP Order to enforce compliance with 46 CFR 25.26-50(c)(1).

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Boarding Officer Action

• Advise the vessel operator that the bracket is defective. Possible negative outcomes:– Early replacement of discharged battery per 46 CFR

25.26-50(c)(1).– Government claims for reimbursing the cost of search

and rescue sorties.

• Issue a 4100 citation for non-compliant EPIRB and follow up with Sector Lead Examiner.

• Worst case: Request Sector use COTP Order to enforce compliance with 46 CFR 25.26-50(c)(1).