Skip to main content

Ask Sail: Two AIS Numbers

I have a Boat U.S.-issued MMSI (Maritime Mobile Service Identity) number for my VHF radio, and now I’m adding a Garmin AIS 600 Class B transponder.
  • Author:
  • Updated:
    Original:

Dean Lewis, Brunswick, Georgia

Q: I have a Boat U.S.-issued MMSI (Maritime Mobile Service Identity) number for my VHF radio, and now I’m adding a Garmin AIS 600 Class B transponder. Does it need a separate antenna, and can I use the same MMSI number that I received from Boat U.S.?

Gordon West Replies

A: Your AIS 600 from Garmin has a built-in antenna splitter. If your current VHF antenna is working well, this AIS unit can share the same antenna without any major loss of VHF performance. You should obtain an FCC marine station license with an FCC-issued MMSI number if you operate your AIS operation well offshore, or if you cruise north to Canada. You’ll then have two MMSI numbers for the same vessel, but as long as you keep your MMSI information up to date, your VHF and AIS transceivers will be properly identified. It would simplify things to have just one number, but your VHF will refuse to overwrite its existing number unless you have an NMEA marine electronics dealer reset its MMSI circuit.

Got a question for our experts? Send it to sailmail@sailmagazine.com

Photo courtesy of Garmin

Related

_DSC8952-2048

Sailing Scholarship for Teenage Girls

The Women’s Sailing Foundation is offering the Sue Corl Youth Sailing Scholarship to one teenage girl, aged 14-19 years old, who wants to expand her sailing experience and needs financial assistance in order to do so. Established in 2015, the scholarship allows the recipient to ...read more

Screen-Shot-2022-01-26-at-9.50.45-AM

Celestial Navigation Part 4

In episode four of The Nav Station’s Celestial Navigation series, learn how to calculate your assumed position and the local hour angle using your Greenwich hour angle and dead reckoning position. Using examples in the western and eastern hemispheres, Andy Howe discusses why the ...read more

AdobeStock_15671180

Orca Encounters in Spain

The waters off the Atlantic coast of the southern Iberian Peninsula can be tough enough as it is, but in recent months resident pods of orcas have created a whole new kind of challenge, ramming boats and chewing off rudders. Though initially confined to smaller vessels, larger ...read more

Screen-Shot-2022-01-13-at-9.26.59-AM2048x

Video: Celestial Navigation Pt3

. In episode three of the Practical Celestial Navigation course, Andy Howe examines the theory behind celestial navigation, the celestial triangle and the celestial sphere, and why it is important to have a basic understanding of each. Topics introduced include zenith position, ...read more

01-LEAD-6.-After-2-years-ashore,-Nada-headsto-the-water-(3)

Sailing in the Time of Covid

In mid-August 2019, my wife, Terrie, and I laid up our Malö 46, Nada, in Falmouth, England, and flew home to Maine. We booked flights back to the UK for May 2020, anticipating a summer of cruising the Atlantic coasts of France and Spain. Then Covid struck. Remember that first ...read more

Ulysse Nardin promo photo

The Ocean Race Names Official Timekeeper

With just under one year before the start of The 2022-23 Ocean Race, Swiss watch manufacturer Ulysse Nardin has been named the official timekeeper of the race. The Ocean Race, formerly known as the Volvo Ocean Race and before that the Whitbread Round the World Race, announced ...read more

Arthur Daniel_RORC Maserati - RORC Transatlantic 2022 - Jan 15th -Social Media-4

Fast Finishes for the RORC Leaders

Over the weekend, the first finishers of the 2022 RORC Transat made landfall in Grenada, led by Giovanni Soldini’s Multi70 Maserati, which was awarded line honors with a corrected time of six days, 18 hours and 51 minutes. Maserati finished ahead of Peter Cunningham’s MOD70 ...read more

Background-02

Notice to Mariners: A Blog from the SAIL Editors

As a teenager, I stumbled across a copy of Derek Lundy’s Godforsaken Sea in the back room of a used bookshop. I had never heard of the Vendée Globe and frankly found all the boat-speak in the first 50 pages a little difficult to get through. But Lundy’s storytelling and the draw ...read more