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Author Topic:   RESCUE 21--The Unrealized Gain
jimh posted 03-05-2011 10:54 AM ET (US)   Profile for jimh   Send Email to jimh  
The United States Coast Guard is in the final stages of deployment of the modernization of their VHF Marine Band radio monitoring and direction-finding system known as RESCUE 21. The RESCUE 21 project brings the radio facilities of the USCG into the modern age of radio communication. With RESCUE 21 the USCG is keeping watch for distress calls from vessels, as it always has, but now with improved capabilities for radio direction finding (RDF) as well as precise position locating using digital selective calling (DSC) data transmitted from the vessel in distress.

Among recreational vessels who are voluntarily equipped with a VHF Marine Band radio, there has been now for many years low-cost equipment which will permit transmission of a DSC distress call that contains vessel position information. Typically the vessel position information would be derived from a GPS receiver, which are also available now at very low cost. I think it is entirely fair to say that equipping a small boat with a VHF Marine Band radio with DSC features and a GPS receiver that provides highly accurate position information is no longer very expensive--to the point where the cost is not really any impediment for recreational boaters. However, in spite of the low cost of GPS and DSC radios, there appears to be a substantial technological hurdle that is preventing a very large majority of recreational boaters from taking advantage of the technology they have already purchased: connection of the GPS receiver data to the DSC radio transmitter. Also, there appears to be some procedural hurdles in radio registration which further prevent optimum use of RESCUE 21.

USCG Rear-Admiral R. E. Day (Assistant Commandant for Command, Control, Communications, Computers, and IT), in a letter to the National Marine Electronics Association (NMEA), cites the following statistics:

"Of the roughly one hundred digital selective calling (DSC) distress alerts we are now receiving each month, approximately nine out of ten do not have position information (i.e., do not have a GPS navigation receiver interconnected to their VHF radio), and approximately six out of ten have not registered their Marine Mobile Service Identity (MMSI)."

I find these statistics to be alarming, but I am not surprised by them. Among the recreational boaters that I know, I suspect that their radio installations are probably in a similar state. While many own both a GPS receiver and a DSC radio, it is all too common to find that the two devices have not been interconnected properly. Failure to obtain an MMSI is not as much of a problem, and I suspect my boating buddies are more compliant than the six out of ten cited by the Coast Guard. However, both the GPS--Radio connection and MMSI registration are problem that prevent RESCUE 21 from working at its best.

I can understand the 90-percent failure rate for boaters to have connected their VHF Radio DSC input to a GPS receiver data output. This is a difficult task to accomplish even for experienced electronic technicians and engineers. As a standards organization, NMEA has done a decent job of providing manufacturers with a recognized standard or protocol for creating electronic equipment that can be interconnected, but in terms of providing a service to boaters, NMEA has failed. Marine electronic devices are difficult to interconnect for most boaters, even though all devices may be compliant with the NMEA-0183 specification. Too often there is a confusing presentation of information in the technical manuals of consumer-level products regarding how they are to be interconnected. NMEA has failed to provide a simple standard for interconnection. There has never been any consensus or recommendation on connectors or wiring, leaving each manufacturer to provide for these in their own way. There has been no consistency in wiring color codes, and as a result there is little consistency between manufacturers in their use of color codes to identify wires by function. Most recreational boaters are more concerned about gaining skill and knowledge in angling for fish, not in spending hours studying technical manuals to interconnect their radio to a GPS receiver or chart plotter. I think NMEA has failed to provide boaters with a simple, universal, and easily accomplished means of interconnecting marine electronic devices using NMEA-0183.

MMSI registration is also a curious matter. Here we have one agency of the government, the Coast Guard, lamenting the low rate of use of registration for a Marine Mobile Service Identity which is offered by another agency of the government, the Federal Communications Commission (FCC). Perhaps the two agencies should talk amongst themselves about this. The FCC will provide boaters with an MMSI number, but only if they obtain a ship station license at a cost of $160. The license is good for ten years. If the licensee needs to change anything in the license data, further fees may be needed. Let me ask this: how many boaters keep the same boat for ten years, live at the same address for ten years, and have the same emergency contacts whose telephone numbers stay the same for ten years? Making changes to license data may require a licensee to pay additional fees. If the USCG wants more boaters to get an MMSI, why does the FCC make it so difficult? Even for boaters who are willing to pay the fees, the process of obtaining a ship station license is extraordinarily complicated. It is so complex that there are websites whose purpose is simply to explain how to use the FCC's websites to apply on-line. My own experience with trying to grasp how to get an MMSI from the FCC was to give up in frustration--too many forms, too many confusing paths to follow.

The USCG and FCC ought to be thankful for BoatUS, who has stepped forward to provide MMSI registration for free using a simple on-line registration and modification tool based on using a web browser. However, having a BoatUS-issued MMSI is only useful for operation in U.S. water. The data is not shared with adjoining nations like Canada and others. In 2011 it cannot be a frightful problem to let Canada know about a few hundred thousand boat registrations. Egads! When I drive to Canada they already know all about my car from its registration, and there are probably several hundred million car registrations among fifty state agencies. One database of a few hundred thousand MMSI registrants cannot be shared?

What we have now in RESCUE21 is a multi-million dollar, multi-year deployment of a modern radio watch system that is being crippled because 90-percent of boaters don't have their radio wired to their GPS receiver, and 60-percent don't have their DSC radio registered with an MMSI. While I think the NMEA and its manufacturer members have done a poor job facilitating these interconnections, and the FCC has put up hurdles to getting an MMSI, we as boaters should do our best to overcome these obstacles. Get your DSC radio wired to your GPS receiver and get it an MMSI from BoatUS.

davej14 posted 03-05-2011 05:10 PM ET (US)     Profile for davej14  Send Email to davej14     
Is there a way to check the MMSI database to determine if you number and associated data are listed and correct?
jimh posted 03-05-2011 05:43 PM ET (US)     Profile for jimh  Send Email to jimh     
You can check a BoatUS MMSI on the database at their website. You can check the FCC license data base on their ship license search website.
anthonylisske posted 03-13-2011 09:43 AM ET (US)     Profile for anthonylisske  Send Email to anthonylisske     

Great thread. I think it is a good warning to those folks who have not made the connections between thier radios and GPS.

I was lucky to purchase both of those electronic devices for my boat atthe same time. I purchased the same manufacturer, so that aided in connecting the devices. I think the greatest obstacles trying to connect if there are different manufacturers with different year equipment.

I do run far off, so I felt the time to register an MMSI and connect the radio was essential. I m not sure if I used my boat in the bay on weekends would have given me the same motivation.

Thanks for the post

jimh posted 03-13-2011 11:50 AM ET (US)     Profile for jimh  Send Email to jimh     
Anthony--Thanks for the comments. I was not sure if anyone had even read these articles.

While the USCG laments not having the GPS receiver connected to the radio transmitter (for sending distress calls with position information), I would like to further add that there is another interconnection that also should be made: the radio receiver should be connected to the chart plotter. This will allow the chart plotter to display the position of other vessels who transmit their position via digital selective calling. For example, if a DISTRESS transmission is received from another vessel, this should be plotted on the chart plotter of the receiving vessel, showing the position of the vessel sending the DISTRESS transmission.

I have made such a connection in my boat's integration of GPS receiver, VHF Marine Band radio, and chart plotter. I have not actually tested it with a DISTRESS call, but I have tested it with some non-distress digital selective calling (DSC) remote position poll requests. I have polled some remote vessels for their position, and, when they respond via DSC, my chart plotter displays their position. It has been tedious for me to find boats that are able to send me their position because it requires that they have a newer radio--a Class-D DSC radio typically is needed--and they have their GPS receiver connected to it. So of the ten-percent of boats with the GPS connected to the radio, there is an even smaller sub-set of them with Class-D radios.

Based on my experience, the percentage of recreational boats who are set up for this sort of integration--connection of GPS to radio and then radio to chart plotter--is very small, perhaps about one-percent if I made a guess.

I am hoping to cajole, encourage, and help some of my boating companions to get their VHF Marine Band radios better integrated with their GPS receivers and chart plotter, so perhaps in the 2011 boating season we could actually exchange DSC messages for remote position and see the results on our chart plotters.

DeeVee posted 03-13-2011 02:06 PM ET (US)     Profile for DeeVee  Send Email to DeeVee     

When I bought my boat it was set up with the Standard Horizon plotter and Standard Horizon DSC radio already interconnected. I have always thought this is one of the greatest ideas since sliced bread.

Unfortunately, as the Coast Guard figures illustrates, it seems that almost no one else on earth feels the same way.

For years I have tried to talk my brother-in-law into changing out his 20+ year old work radio for a new DSC radio and connecting it to his plotter. I just get one step up from a blank look from him.

The position polling request feature would be awesome for people who are fishing the ocean in different boats. More situational awareness is always a good thing, not just for fishing convenience, but safety as well.

I don't really get why people don't make the connection and get the MMSI.

Doug Vazquez

SJUAE posted 03-13-2011 03:36 PM ET (US)     Profile for SJUAE  Send Email to SJUAE     

My 2006 210 Outrage factory fitted Northstar Nav package was already setup. I suspect many others are if they take the BW options.

When I replaced this with my Lowrance HDS and Standard Horizion VHF I made the same connection although I still don't have a local MMSI here in UAE due to high cost, although they will register PLB as it's a pure safety device for free.


anthonylisske posted 03-15-2011 06:31 AM ET (US)     Profile for anthonylisske  Send Email to anthonylisske     

Yes the connection to chartplotter is essential. On my 5 year old Standard Horizon CP1000 and Standard Horizon VHF, I knew I connected it properly when my VHF handset would display longitude and latitude. This meant the distress was connected. (I luckily have not had to try distress signal either).

During the connection process I had to call standard horizon and get a wiring diagram, to be honest, I was absolutely stunned when it worked. (because it was so difficult)

Like you, I have only used the DSC 1 time, with my brother, lol. He is the only person I know that has done it too. Super cool feature though.

Great functionality.

old sparks posted 03-22-2011 02:41 PM ET (US)     Profile for old sparks  Send Email to old sparks     
In Canada, you can look up MMSI numbers on-line at:

[Suggests that by entering the string] 316 [in the MMSI search field that the data base search] will return all ships in the database.

jimh posted 03-22-2011 09:17 PM ET (US)     Profile for jimh  Send Email to jimh     
Thanks for the URI to the Canadian MMSI database.

It is important that boaters properly connect their modern VHF Marine Band radios with DSC DISTRESS CALL capability to a source of accurate position data such as a GPS receiver. And it is important that boaters register their boats to obtain a marine mobile service identifier (MMSI).

jimh posted 09-24-2011 10:16 AM ET (US)     Profile for jimh  Send Email to jimh     
The United States Coast Guard recently issued MARINE SAFETY ALERT 04-11, titled:


You can view the alert on-line at

This alert reprises the USCG's earlier announcement that an astonishing nine out of ten VHF DSC distress alerts received by the Coast Guard do not contain position information about the vessel originating the transmission.

To assist boaters in establishing a wired connection between their VHF Marine Band DSC radio and their GPS receiver, the USCG has created a document containing wiring details for connecting various popular devices. See pdf

jimh posted 09-25-2011 08:56 PM ET (US)     Profile for jimh  Send Email to jimh     
I consulted the USCG document for advice on connecting my GPS receiver to my radio. I have a Lowrance GPS receiver and a Standard-Horizon radio. The advice in the document made no sense at all. The USCG-recommended wiring suggested using a black and white wire from my Lowrance GPS device. The device does not have any black or white wires in its NMEA-0183 serial data connector cable.

It might be interesting to hear from other readers regarding if the suggested connection for their devices appeared to be correct in the USCG document.

tmann45 posted 09-25-2011 10:18 PM ET (US)     Profile for tmann45  Send Email to tmann45     
The Garmin 5000 series and my Standard Horizion wires are correct. My HDS-7 has blue and yellow NMEA 0184 wires, not black and white.
kmev posted 09-26-2011 10:00 PM ET (US)     Profile for kmev  Send Email to kmev     
I just connected my ICOM 504 to my Garmin 440s. The ICOM did not have an RCA plug as indicated by the USCG document, but instead had a [shielded] cable for both the IN and OUT on the radio.

[Details of connection process elided--jimh]

When I asked all my boating friends for their MMSI, they either didn't know what I was talking about or said they forgot what it was and weren't too interested in scrolling through their radio menu to retrieve it.

jimh posted 09-27-2011 09:36 AM ET (US)     Profile for jimh  Send Email to jimh     
Thanks for two reports of inaccuracy in the USCG data sheet on interconnections. I don't think it is really possible to provide sufficient detail about every radio and every chart plotter. The underlying problem with these interconnections is a lack of standardization. The NMEA missed the boat (so to speak) on this standard. If they had specified something as simple as a wire insulation color code for the serial data signal wires, it would make interconnection much simpler.

Any other reports of the accuracy of the USCG data sheet information?

jimh posted 10-27-2011 09:18 AM ET (US)     Profile for jimh  Send Email to jimh     
An updated coverage map of the RESCUE21 system now shows a substantial amount of the Great Lakes has beed added.

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