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Emergency Position Indicating Radio Beacon (EPIRB)
Personal Locator Beacon (PLB)
Maritime Mobile Service Identity (MMSI)
Digital Selective Calling (DSC) VHF Radio
Automatic Identification System (AIS)
USCG Navigation Center of Excellence

An FCC LICENSE NOT REQUIRED for recreational EPIRB's, PLB's, VHF Radio or AIS Devices plus
Registering Beacons & DSC VHF Radio MMSI's are FREE!

In an emergency, these devices send an alert to rescue authorities containing location & vessel's ID!

The vessel ID for a properly registered devices provides timely access to critical information needed to help save lives.
So be sure owner/operator names, address, phone numbers, vessel description, contacts, medical conditions, etc. are current!

Don't have an EPIRB, but going offshore or on an extended voyage,
rent one from BoatUS Foundation

EPIRB Types:

Category I & II 406/121.5 MHZ EPIRB's come in a wide variety of designs, styles, and form factors - Link to 
       NOAA Emergency
Detectable anywhere in world
Recognized by GMDSS
Available with integral GPS receiver
Category I  -  Automatic-activation; hydrostatic release 'Float-free' bracket
Category II  -  Manually activated; activates in water if removed from bracket
Inmarsat E - Currently not sold in U.S.
1646 MHZ  -  Float-free, automatic-activation.
Detectable by INMARSAT system.  Recognized by GMDSS.
Alerts received from INMARSAT routed to USCG.  FCC considering recognizing.
Phased out; No Longer Recognized
Class A, B & S - (121.5/243 MHZ)
Class C - (VHF Channel 15/16)
USCG recommended Category I 406 MHz EPIRB's - Link to U.S. CG  EPIRB page

Category I & II 406 MHz EPIRB's  -  only units sold in US certified & recommended by USCG

If properly & professionally installed, USCG prefers Category I to Category II units

406 MHz designated for distress use internationally.  Best 406 MHz EPIRB's have embedded GPS receiver so vessel identification & location information (2 to 5 km) can be sent to rescue authorities immediately upon activation anywhere in world (no range limitation).  These units also include a 121.5 MHz homing signal to allow air & rescue craft to quickly locate them.

406 MHz EPIRB's can be detected by International Satellite System for Search & Rescue (COSPAS-SARSAT & GOES weather satellites).  GEOSTAR detected alerts are immediately sent, but without location unless EPIRB is equipped with an integral GPS receiver.  EPIRB's detected by COSPAS-SARSAT (e.g. TIROS N) provide distress location, but information can be delayed as much as two hours.

EPIRB Testing

EPIRB should be periodically examined for water tightness, battery expiration date & signal presence.  406 MHz EPIRBs can be tested through a buitl-in self-test function or inside a container designed to prevent reception of its signal.   Testing a 406 MHz EPIRB by allowing it to radiate outside such a container is illegal.

EPIRB Battery Replacement

Category I EPIPB attached to PFD - Link to NOAA EPIRB Inspection page

406 MHz EPIRBs use a lithium battery designed for long-term low-power operation.  Batteries must be replaced by a manufacturer approved dealer before date indicated on EPIRB label.  If battery replacement is not done properly, EPIRB will not operate for specified duration in a distress situation.

406 MHz EPIRB Registration is mandated by Federal Communications Commission (FCC)

Register 406 MHz EPIRBs with NOAA & update information if owner, boat, address, phone number, etc. change.  If EPIRB is sold, make sure purchaser re-registers it.

USCG strictly enforces this requirement, since Alerts from unregistered units can delay response efforts as much as two hours & if transmissions is cutoff for any reason, can leave unit ID & location unknown causing unnecesssary loss of lives.  USCG routinely refers unregistered EPIRB non-distress activations (e.g. hoax, gross negligence, carelessness or improper storage & handling) to FCC, but has suspended forwarding non-distress activations of properly registered units, unless activation was due to hoax or gross negligence.  FCC prosecutes cases based upon evidence & will issue warning letters or notices of liability with fines up to $10,000.

Registration information Use

Information entered into the Beacon Registration Database maintained  by NOAA/NESDIS is automatically sent to appropriate USCG SAR Rescue Coordination Center (RCC) on EPIRB activation so response can begin (confirm distress situation exists Category II 406 MHz Portable EPIRB - Link to Wikipedia EPIRB page & arrange appropriate rescue efforts) as soon as an alert is received.

RCC watchstanders will attempt to contact owner/operator at phone numbers listed in database to determine if:

  • vessel is underway (thus ruling out false alarms due to accidental activation or EPIRB malfunction)
  • intended route of vessel, if underway
  • number of people on board & any known medical conditions
  • other relevant information to search & resuce efforts

When RCC personnel call listed contacts, they will have information provided on registration form.  If contacts can provide additional information, it will help SAR personnel be better prepared to assist.  Thus, always let listed contacts know as much about your intended voyage as possible (i.e. route, stops, area you normally sail/fish/recreate, duration of trip, number of people going, ages, medical conditions, etc.).  Contacts, if they so desire, can ask RCC to keep them informed of any developments.

How To Register 406 MHz EPIRB

Download registration form
Request registration form by fax (301-817-4565) or phone 1-888-212-7283 (outside U.S. call 301-817-4515)
Same phone numbers may be used to ask questions or request information
Send or fax completed form to:

Category II 406 MHz EPIRB - Link to BoatUS EPIRB page SARSAT Beacon Registration
E/SP3, Room 3320, FB-4
5200 Auth Road
Suitland MD 20746-4304

For more information see NOAA SARSAT Homepage


Personal Locator Beacons (PLB's)

A PLB is a pocket-sized emergency 406MHz beacon, a scaled down version of the EPIRB (Emergency Position Indicating Radio Beacon) and ELT (Emergency Locator Transmitter) that boaters and pilots, respectively, have had available to them for years.

PLB Registration Form                  Return to Top of Page

Maritime Mobile Service Identity (MMSI)  /  MMSI FAQ's

A nine digit number used by maritime equipment such as digital selective calling (DSC) and automatic identification systems (AIS) to uniquely identify the unit (vessel or radio station).  MMSI's are regulated and managed internationally by the International Telecommunications Union (ITU).  MMSI format and use is documented in Article 19 of the ITU Radio Regulations and ITU-R Recommendation M.585-5.

MMSI Registration is free for recreational boaters from Boat/US.  Please review instructions & gather required information before proceeding to the BoatUS MMSI Registration site.

Login to the BoatUS MMSI site to update MMSI Registration Information (owner, address, contacts, phone numbers, boat description, etc).

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Digital Selective Calling (DSC)

DSC is a standard for sending pre-defined digital messages via medium frequency (MF - 2187.5 kHz), high frequency (HF - 8414.5 kHz) and very high frequency (VHF - Channel 70) maritime radio systems.  It is a core part of the Global Maritime Distress Safety System (GMDSS).  Ocean going vessels now monitor VHF Channel 70 for Distress Calls (no longer monitor Channel 16).

As of March 25th, 2011, the FCC has made it illegal to buy, sell, or install some DSC capable VHF radios. After this date, all VHF radios must not only be DSC capable, but must also be Class D compliant.

Connecting a chartplotter to your DSC VHF radio will make the vessel's GPS position information (LAT/LON) available for transmittal by the VHF radio in an emergency to aid rescuers or to support other DSC functions such as sending your position to buddies so they can easily locate you (if they have similarly equipped systems).

Making the connection between a Chartplotter & DSC VHF Radio

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Automatic Identification System (AIS)  /  AIS Online

AIS (47 CFR 80.5 Definition) is shipboard broadcast system operating in VHF maritime band that is capable of handling well over 4,500 reports per minute & updates as often as every two seconds.  Self-Organizing Time Division Multiple Access (SOTDMA) technology is used to ensure reliable ship-to-ship operation.

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