DSC- Digital Selective Calling MMSI numbers - not just for emergencies

[Vincentc]

The boat came with an ICOM 504 connected to the Garmin plotter. Other than thinking the red distress button was a nice feature and finding the VHF read out showing my lat/lon interesting, I did not give it much thought, until I came across an article in an old issue of Practical Sailor.

I did not know that you could use DSC for routine calls to other boats and it appears to work like a cell phone text message. If you have the other boat's MMSI number, You can send a message just to that boat, request that he call you and also give him your location.

To do this, you and the intended recipient must have MMSI numbers, available from BoatUS online. The online process took less than 10 minutes.

My VHF had never been programed, and it was pretty simple to do and just that step should enhance the distress feature of the VHF, since your distress call would also identify you to the CG.

I am also intrigued with the idea of setting up a station at our home to receivce DSC calls from the kids when they are out on boats. Cell phone coverage at the islands here is uncertain and the ability to get a boat's position is particularly attractive. I can think of a lot of non-distress but problem situations that would benefit from DSC messaging.

Any comments with experiences with DSC and or the use of a VHF station at home?

Regards,
Vincent

 

[Canuck Dennis]

Illegal.

 

[Vincentc]

Dennis,
Less is more, but sometime it becomes cryptic.

 

[GJH]

I think he is trying to say, that in the US at least, you must have a special license to operate a land-based VHF. These are typically for marinas, tow services and other commercial ops. You would have a very difficult time getting an MMSI for it as well.

By the way, an MMSI is really an essential part of having a DSC radio, glad you completed the process. The same MMSI can and should be identified with an EPIRB too.

 

[Fanfare]

You can get an MMSI for free from BoatUS. However, if you travel internationally on your boat and/or you have an SSB you will need an FCC station license. They will issue you an international MMSI on the license which won't be the same as the BoatUS one. I had to send my VHF back to the manufacturer to have them change from my old to new MMSI. And even though both were "legal" only the FCC one came up when I checked their database.

 

[pmurphy]

I have recently gotten into the DSC functionality of my VHF radio. Obviously, as a back-up to an EPIRB, it is a great thing to have operational.
I've been an advocate of getting my friends set up with MMSI numbers and making sure their VHF's and GPS's are wired properly. Out of about a dozen people I checked with, only one had it working, most didn't even know what DSC was.
Last week a bunch of us were in the Florida Keys for mini-lobster season (most on smaller boats) so I had a good test bed for how well it works for non-emergency calls. On a scale of 10 I'd give it about a 5 for reliability. Hopefully in emergency mode it works better.
We did both individual calls and position requests between the boats. There were times the position request came back with the last three GPS digits as zeros. Other times when I was certain the radios were in range, the position request didn't go through.
The DSC set up from radio to radio is very different so you'll most likely need the manual to get it set up. Also, be sure that both the GPS in and GPS out wires from the radio are properly connected to the GPS.
When it works, it is great. When you ping another boat thier position pops up on your GPS.

 

[lumina]

Hi All,

Vincent,

A few weeks ago we had new VHF antennas installed and at the same time I had them integrate the VHF radio to the Garmin. I had hoped to have them program in my mmsi number but I didn't have it with me. Now I'm waiting for them to come back and do it.

Is it easy to do ? (for a non technical guy)

Could you provide instructions ?

I understand that if you attempt it and do it wrong twice you've got to send the VHF unit back to the MFG for a reset ? ?

 

[Vincentc]

When it comes to electronics I am semi literate. I have the children set up my cell phone.

Since they are not into boat electronics, I downloaded the Icom VHF manual off of the internet and followed the instructions in the manual. With the Icom 504 on Lilly Marie, no problem for me, it has a large read out and I programed the MMSI number first time.

On the 25 Wellcraft, we have an Icom 402 which has a small screen and and the read out is very limited, it only shows 5 digits of the 9 digit MMSI. I don't know if I did it right or not. According to the manual, you can only program it twice, so I am going to check it and try again when I have plenty of time.

If I did it, you should be able to, but a big display helps. I do not think it necessary to hire someone to input the MMSI.

Thanks for the input regarding DSC performance. Sad to hear it is not that relaible. I agree that it is important to get folks you know to obtain and program an MMSI number. It is a feature and need I do not think many people are familiar with.

Regarding a land station, I wonder if it is OK to monitor/recieve signals from a shore based VHF and will be OK if you do not transmit. It would be nice to have a means for the kids to check in via DSC and advise of a problem. I could then go down to the boat and transmit.

 

[GJH]

The method of entry varies from radio to radio. It was very easy to do on my two different Standard Horizons, you can only screw up if you rush through it. I recommend getting the FCC license MMSI, you never know when cruising plans might change. Plus you get a call sign as well, you're already to cruise anywhere. It was an easy process.

George
"Incentive"
WDE7997
367400250

 

[DeeRow]

...There were times the position request came back with the last three GPS digits as zeros....

NMEA is a text based message system. Unfortunately, the format of the lat-long can vary with devices. Garmin MFDs let you select the format of the lat-long as well as the precision. When connecting a VHF to a chartplotter, you need to verify that the position displayed on both units are the same. Garmin is the only chartplotter that I know of that can be configured to match other connected devices.

Mark

 

[Trojan]

It's not illegal to receive any radio frequency for the most part. Cell frequency's are a no on. It is illegal to use or tell what you hear on some frequency's. Land marine radios are illegal, but many people living near the shore have and use them. If you don't abuse them, I don't think you will be bothered. It would be as if you were at your dock in you boat.

The CG is using this system in very few places. It's used I think only in the south at this time. With the money crunch I don't think it's going to expand much. They just refurbished almost all of the old RDF stations and then shut them down due to lack of money to monitor them. At this time there are no provisions to have use of the system on the Great lakes, ever. I have the capabilities on my boat but never requested any numbers. I think it's a good idea.

BILL

 

[GJH]

Beg to differ Bill, they have already done a rescue in Michigan and are continuing to roll out the system. The saltwater coasts of the US is 99% covered, as well as the Hudson and Columbia rivers. Here is a current coverage map showing where the stations are (the little circles are not the actual area covered):

http://www.uscg.mil/acquisition/rescue21/images/R21nationwide.jpg

And here is additional information:

http://www.uscg.mil/acquisition/rescue21/pdf/acceptanceschedule.pdf

http://www.uscg.mil/acquisition/rescue21/default.asp

 

[pmurphy]

I've set up almost a dozen of these in the last few months. Some radios give you one chance to get your MMSI number in correctly, most give you two chances. You just have to follow the radio owners manual instructions carefully. Once that is done, you can then put in your friend's MMSI numbers so you can call them or find out thier locations.
On the GPS side, once the wiring is done correctly to the VHF, most radios received the boat's position without any issues. I did have a lower end Garmin GPS that I had to change the signal format on. It was set to a Garmin proprietary string and the VHF radio wouldn't accept it.
On the wiring side, you know you have the first part right if your radio shows your GPS coordinates on the face of the radio (most radios). Some that I did (lower end models) had an icon on the face of the VHF radio to indicate a GPS fix.
A second wire from the VHF radio needs to be attached to the GPS for the "GPS out" from the radio to the GPS. The reason you need this wire hooked up is that when you ping a friend for his location, the location will appear on your chartplotter. Also, if someone hits the emergency DSC button, that person's location will appear on your chartplotter.
Another thing that can be programmed in most chartplotters is entering in names for MMSI numbers. When the chartplotter receives a gps location associated with a certain MMSI number, instead of the chartplotter just showing the MMSI number, the person's name will appear.

 

[Trojan]

Beg to differ Bill, they have already done a rescue in Michigan and are continuing to roll out the system. The saltwater coasts of the US is 99% covered, as well as the Hudson and Columbia rivers. Here is a current coverage map showing where the stations are (the little circles are not the actual area covered):

http://www.uscg.mil/acquisition/rescue21/images/R21nationwide.jpg

And here is additional information:

http://www.uscg.mil/acquisition/rescue21/pdf/acceptanceschedule.pdf

http://www.uscg.mil/acquisition/rescue21/default.asp

That's great. My info was a year old so I didn't follow up on it. I will have to check our area and see if it operational. Thanks for the up date. With out leader you never know what systems are working or not.

BILL

BILL