DSC, MMSI & Rescue 21

[Craig Illman]

Puget Sound Fleet 5 C34 Owners –

A couple years ago, I had to replace my VHF radio after accidentally hitting the 12V DC power with 120V shore power. (Yes, turn things off when messing behind the panel). The new radio I bought, the cheapest at WM at the time, had a feature called "DSC". After reading the manual, I discovered DSC, among other features, provided unique identification of my vessel when the distress button was pressed. All that was required was to enter a MMSI number into the VHF radio's static memory. I also found I already had a MMSI number on my FCC station license. You can also be assigned a MMSI number from an organization such as BoatUS. Step one was complete, they'll know Craig on Espresso was sinking, but where? The VHF also had a NMEA 0183 input that would allow Lat/Lon data from a GPS to be included with the distress call, but I rarely used the old black & white Garmin unit at my Nav table, so I didn't pursue getting them interconnected.

Last spring, I got real serious about interconnecting all the NMEA capable equipment on my boat and invested in a new chartplotter and more capable VHF. I'll focus on just my chartplotter and VHF interfacing.

I picked up a Garmin 492 on closeout, it being superseded by a unit that supported XM satellite weather. I also purchased a Uniden UM525 Loud Hailer. There's a plethora of chartplotters on the market and many VHF options, I just want to share the opportunities when you can connect them together. Both devices both input and output NMEA data. I'll list a bunch of web links at the end of this.

Among its many features, the Uniden UM525 will not only use DSC for distress transmit and receive signaling, but will allow directed calling of other VHF stations to their MMSI number.  You can build a directory of friends' boats MMSI numbers and save them by boat name. If the radio receives a DSC call, it will automatically switch channels, if desired. Lastly, when a DSC call is received, it will put an alert on the NMEA data bus. The Uniden also uses GPS information for more than distress Lat/Lon. It's capable of automatically picking US or Canadian channels and displaying the appropriate local time. It will also repeat from the GPS, course and speed information.

The Garmin 492's DSC features allow an alarm to display on the screen and emit an alarm tone. It will log and display the calling vessel's position. You can then display the caller on your chart and/or create a waypoint.

DSC need not be only used in an emergency. It's limited only by the range of your VHF. You can use it to directly contact another vessel without trying to hail it on channel 16 or the VTS channels. If you have AIS installed and integrated to your chartplotter, the MMSI number is included in the AIS data stream. You could contact that approaching tug and verify its course.

Rescue 21 is an initiative by the Coast Guard to upgrade their facilities to more quickly and accurately respond to emergencies. For more information, see:

http://www.piersystem.com/go/doc/21/141255/
http://seattletimes.nwsource.com/html/localnews/2003725556_coastguard29m.html

I don't intend to endorse any specific product, just encourage you to take advantage of existing capabilities on your equipment and consider these features when you need to replace or upgrade your gear. Of course, I'm open to share my experiences with other boat networking topics.

Craig Illman
C34 #1150 Espresso
MMSI: 367022920

Uniden UM525

http://www.uniden.com/products/productdetail.cfm?product=UM525

Garmin 492

https://buy.garmin.com/shop/shop.do?pID=369

DSC – Digital Selective Calling

http://www.boatus.com/husick/c_dsc.asp
http://www.navcen.uscg.gov/MARCOMMS/gmdss/dsc.htm
http://www.navcen.uscg.gov/marcomms/gmdss/dscworks.htm
http://www.boatsafe.com/nauticalknowhow/dig0101.htm
http://www.ybw.com/ybw/vhf/dsc.html

MMSI

http://www.navcen.uscg.gov/MARCOMMS/GMDSS/mmsi.htm
http://www.boatus.com/mmsi/

NMEA 0183/2000

http://en.wikipedia.org/wiki/NMEA_0183
http://www.gpsinformation.org/dale/nmea.htm
http://www.tronico.fi/OH6NT/docs/NMEA0183.pdf
http://en.wikipedia.org/wiki/NMEA_2000
http://www.jackrabbitmarine.com/Categories.bok?category=NMEA+0183

AIS

http://en.wikipedia.org/wiki/Automatic_Identification_System
http://www.navcen.uscg.gov/enav/ais/default.htm
http://www.boatingsf.com/ais_explain.php
http://www.milltechmarine.com/

[Craig Illman]

To all - The March issue of 48 Degrees North has an article on DSC, possibly a little more information than I provided above.

Craig

[Ray & Sandy Erps]

Craig,

If I wanted to hail you using your DSC id #, would I have to know what frequency you're monitoring and then hail on that frequency?

We're going to be out for the long weekend too.  I don't know where yet, but I thought I'd enter you into our VHF address book and perhaps give you a shout to get some practical experience with DSC.

Ray

[Craig Illman]

Ray - The way I understand it, if you direct call me via my DSC MMSI number, my radio will automatically switch over to channel 70 to receive your call. Send me your MMSI number. We're not getting out until Sunday.

Craig

[Ray & Sandy Erps]

I entered your number into my directory just the other day.  I don't remember my number though.  I'll see if it's accessible online where I registered and get back to you.

[Ray & Sandy Erps]

Craig,

We left town Friday just before noon to see if we could get the dock at James Island.  It was already full.  We're over at Spencer Spit now and may try James again tomorrow.  My MMSI is 338069638.  It's hooked to my GPS.  I'll have both on Sunday around noon if you want to try polling us for automatic location.

Ray

[Craig Illman]

Ray - We'll probably be off the dock around 10-ish on Sunday. If Linda will assent to some helm time, I'll try to give you a call.

Craig

[Ray & Sandy Erps]

We broke down Saturday and had an exciting trip back south down Rosario with no wind and no motor.  We drifted like a log at 5 knots past Black Rock.  I got the engine patched up before Bird Rocks and then idled back into Skagit Bay.  We're at Hope Island now.  I'll still have the radio on tomorrow between 10 and noon.

Have a good trip.

[Ray & Sandy Erps]

Well, nutz!  I apologize Craig.  I started working on my teak and forgot all about turning the radio on.  Around 3:00 I realized my mistake and turned it on and pinged your radio for a position report.  It looks like my radio does two broadcasts on 70, the first on low power, the second on hi power then it goes back to the working channel.  I think I got the DSC stuff figured out after reading a bit more on the boat.  Neat technology when it's used by more people.

[Craig Illman]

Ray - So, when you called with the "position request" Did you get my position, lat/lon? It seems like it would really be best to practice with someone close to understand what the radio display is trying to communicate. We were motoring at the north end of Lopez when you called this morning. I didn't have my WHAM mike out in the cockpit and it was a bit loud in the cabin.

I'll send you an email on my adventures yesterday.

Craig

[Ray & Sandy Erps]

A WHAM mic is on our list too.  The VHF down below isn't very useful when we need it at the helm.  I bought a little external speaker to wire out in the cockpit, but after this weekend, Sandy and I both agree that a WHAM mic would have been nice.

I wasn't sure whether I got your postion report or not.  I was messing around with the radio and shortly after I did a position report POL, I pushed another button on the radio, I think it was marked display, and a lattitude and longitude started scrolling across the bottom of the display.  That puzzeled me, and I wasn't quite sure if it was my location or perhaps yours. I looked at the lattitude real quick and compared it to the lattitude displayed on our gps and it seemed that they matched, so I figured it was my postion being displayed. 

I think I got some of the features figured out this weekend, but I agree, it would be nice to be nearby and confirm that all the features are working.

[Randy and Mary Davison]

Craig,  I'm working on cables and interfacing so we should be able to try it out in the next week or so.

[Craig Illman]

Randy & Ray - I also didn't get an alert on my chartplotter like I expected. I didn't have the PC running with the NMEA log going, so I don't know if the Garmin didn't display the message, the VHF is mis-wired or something didn't pass through my NMEA Mux.

Lots of opportunities, but it would be nice to test with someone just down the dock with a cell phone. I'll probably be up at the slip both Saturday & Sunday.

Craig