DSC Works

Friday, as we went from Reid Harbor to Spencer Spit, I was startled by an alarm on my boat's VHF. At first I did not know what it was but I realized it was a DSC (Digital Selective Calling) distress call. My VHF displayed the latitude and longitude of the sender. Before I could figure out if I was close to the sender, Victoria Coast Guard replied. It was a pair of kayakers that had gotten in real heavy water somewhere in Vancouver Island and needed help. Within 10 minutes a passing boat came to their assistance. Apparently the kayakers had a handheld VHF/GPS like the Uniden Mystic.

I thought DSC was a great idea and now I'm convinced it is. With a push of the button you can send a distress call along with your position. As a matter of fact, if your boat is registered in the US and has an MMSI number from Boat US (US waters only) or the FCC (US and international waters), the distress call will include this number which will allow the CG to identify your boat, the owner, etc. I assume a Canadian registered boat can also get an MMSI through different channels.

I understand that Canada CG has implemented DSC and the USCG will implement it soon. In addition, many commercial boats are required to have it and many pleasure boats also have it.

Raul

[SomeSailor]

Yeah, it's pretty slick stuff. You're the first I've heard say they'd seen it working in the real world. You can do other cool things with it too. You can do "selective calling" on some radios that allows you to "call" another MMSI directly on any channel, and they'll automatically channelize and receive your message. Effectively eliminates hailing.

Here's a cool link from the Coast Guard. Scroll down to the Class D units.

USCG DSC Standards (http://www.navcen.uscg.gov/marcomms/gmdss/dsc.htm)

It is pretty cool stuff. The only downside I see is that most recreational craft VHFs use the same transceiver for DSC as the rest of the VHF radio. If a DSC call comes in while the radio is is transmit mode, it won't be received. Standard Horizon now has a new radio with a dedicated DSC receiver that will get a DSC call regardless of whether the radio is in use or not. I get around this by having two DSC VHFs, one stays set on Ch 70.

Also, I've spoken to a number of boaters with a DSC VHF that have no clue what DSC is, let alone know how to hook up the NEMA output from their GPS to the VHF.

Raul

[SomeSailor]

You don't need to stay on channel 70 though. DSC will be recieved regardless of what channel you've got selected. My understanding is also the minute you hit the DSC button, it channelizes to 70, and transmits the nature of your emergency. Its capable of sending lots of stuff, but part of the continuous broadcast is your current channel. It keeps you from getting lost in the "knobology".

As far as missing a transmission, the minute you stop talking, you're going to receive the DSC broacast, regardless of what channel you are on.

Hooking them up properly is going to be a whole different story. Most folks get lost even with the three wires required :)

That's not what either of my radios' manuals say. I agree that transmitting a DSC signal will occur on Ch 70, regardless of the channel you have selected.

The issue is receiving a DSC signal. If you are not transmitting when a DSC signal comes in, your radio will switch momentarily to Ch 70 and receive it. If you are transmitting while the DSC signal is coming in, you will not receive it. This is why manufacturers are coming ot with radios such as Standard's GX3500S: http://www.standardhorizon.com/indexVS.cfm?cmd=DisplayProducts&ProdCatID=83&encProdID=gBGFfp2v4RY%3D&DivisionID=3&isArchived=0

Raul

[SomeSailor]

Yes. But as long as the DSC is activated on the vessel in distress, their call will get through. It's going to broadcast continuously and updates position data on the fly. Depending on the quality of your unit, there are lots of cool things they can do, but just because you are briefly transmitting, it doesn't mean you wouldn't hear their call a second later.

Also... channel 70 is repeated (as 16 is in most places) so the first responders will get get their info and hail for other boats in the vicinity. Even if you were talking, their MMSI data is transmitted in less than one second, so the odds of missing any alarm are pretty much nil.

So why is Transport Canad requiring commercial vessels over 8m long to install a separate VHF for DSC or a VHF with a dedicate, separate DSC receiver built in?

Raul

[SomeSailor]

Commercial vessels fall under a completely different set up guidelines. Safety of Life at Sea (SOLAS) regulated ships are required to utilize Class A / B radio equipment and have been using DSC for some years now. SOLAS compliance also requires manned watches and EPIRB and other more stringent stuff.

What I can tell you is when you hit that DSC button and then transmit, your NMEA data is gathered from your GPS, and that along with MMSI and other such data (course, speed, time of last report, channel, nature of emergncy, etc) is transmitted as a digital word in less than 1 second. That information hits the DSC monitoring vessels (commercial, air and Coast Guard), where it is repeated to all vessels in that area.

Its just like when talking to Coast Guard Group Seattle, from the San Juans. They're being repeated over landlines and the transmission covers tens of thousands of square miles instantaneously. The same goes for channel 70 and DSC (when they come on line next year).

[Dawn Dreamer]

Norton Rider,

I am pleased to see your positive comments on DSC. I was certainly impressed with the concept when I first ran into it, but since all of our boating for the past few years has been on the canals of France, where VHF is very little used by recreational boaters (I have used Lady Jane's VHF only twice in five years), I have had no experience with DSC.

But we're getting back into boating on the west coast, and in refitting and re-equipping Dawn Dreamer, a DSC radio was one of my priorities. I chose the Standard Horizon Class D GX3500S, and we both took the Power Squadron's new DSC Endorsement course. There is a bit of information on all of this on my site at: http://www.dawndreamer.ca/making_her_ours.htm

We're getting pretty close to our first sea trial and shake-down cruise after a rather lengthy make-over, and hope to spend all of August, September and early October on the water.

Nice boat and website, Michael.

I've got what was the top of the line Standard Horizon radio 2 years ago. It also has all the bells and whistles and I'm pretty happy with it except for a couple of things: 1- The fog horn is pretty feeble. I think I'm going to buy a horn timer and use it instead. 2- The Ram mike's speaker volume is too low for an open flybridge. I'm going to install a remote speaker to boost the volume a bit.

Standard may have addressed these issues with your unit because it has higher hailer/fog horn output and the new Ram mike has a larger mike/speaker.

Raul

[Dawn Dreamer]

Raul,

Thank you for the comments on our site and boat.

The Ram mike's speaker volume is too low for an open flybridge.
Since we intend operating Dawn Dreamer almost exclusively from the fly bridge, I installed the radio there to give us full access and maximum speaker capabilities. When we tested the radio after we were back in the water, we found the ram speakers easily overcame the machinery noises on both the quarterdeck and in the lower helm, so it appears that Standard has properly addressed the volume issue.

We haven't tested the bells and whistles yet.

[SomeSailor]

I couldn't help but smile when you said quarterdeck Michael...

Never heard of anyone refer to their boat's having a "quarterdeck" :D

I REALLY need to get a bigger boat... :(

[Dawn Dreamer]

Quarterdeck is a much more appropriate term in my mind than is sundeck; it is after all, the deck in the quarters of the vessel. The term sundeck brings to mind a patio or deck out the back door of the house. :D

[SomeSailor]

I just spent 23 years in the Navy and many long hours standing actual Quarterdeck watches... your proper terminaology would be more along the lines of the "Bridge" if talking about the flybridge area, or maybe "Pilot House" if talking about the area you steer from below. The "quarterdeck" would be more like the swimstep... :shock:

It's generally considered the aft quarter of a ships upper deck (not really to do with where your quarters are" :) , sometimes called the "poop deck". It's all lost in the translation along the way I suppose though. Heck on a nice big boat like yours they could call it the "Promenade Deck"... :P

[bradvo]

How about aft deck, it is an aft cabin boat. Heh?
Brad

[SomeSailor]

Actually...

In the REALLY olden dayz... :)

There were two "castles" on a ship. A forward "castle" and and after "castle". Hence the term "Foc'sle". This was later changed in the design of the ships and this after area dimished in size. To about 1/4 of the ship's deck area... hence the "Quarterdeck".

The ships brows, were extended from this area and the crew was allowed to embark and dsiembark from here. This is where my watches came in the Navy... as "Officer of the Deck", we got to stand Quarterdeck watches and protect the and control the ships boarding parties.

[bradvo]

But not before dmcb days Mike? :)

[Dawn Dreamer]

During my eighteen years in the Navy I never had to stand a quarterdeck watch; my watches at sea were on bridge as a watchkeeping officer. In port, as Officer of the Day, they were stood in the comfort of my cabin or in the wardroom with the necessary rounds each watch. In all of the ships the Queen gave me to play with, the quarterdeck was the aftermost weather deck. Webster defines it as, "the after section of a ship's upper deck".

In both of our current boats, the one in France and the one in Point Roberts, we have aft cabins with a weather deck above them, so the term quarterdeck is not only the correct one, but I find it much more appropriate than the generally used "sundeck".

I recall often hearing the USN incorrectly refer to the quarterdeck as the fantail, and whenever we heard a pipe such as "... to muster on the fantail", it always got a laugh from us. In nice weather, we used to muster the crew on the quarterdeck for grog, and we assumed the U-alls were mustering on the fantail for iced tea. :lol:

[SomeSailor]

In port, as Officer of the Day, they were stood in the comfort of my cabin or in the wardroom with the necessary rounds each watch.

Ah... the Canadian Navy. :D

Inport we shift our OOD watch from the Bridge to the Quarterdeck. I wouldn't want to be the Officer of the Deck who got caught in the Wardroom during his watch :)


In all of the ships the Queen gave me to play with, the quarterdeck was the aftermost weather deck. Webster defines it as, "the after section of a ship's upper deck".


The Queen never gave me any... but the Command Duty Officer (2nd in command while CO/XO are ashore) defined it as our Officers brow :) About halfway down the stbd side on an aircraft carrier. (you know the big ones with the pretty airplanes up on the sundeck.... none like that in the Canadian Navy I suppose) 8)


In both of our current boats, the one in France and the one in Point Roberts, we have aft cabins with a weather deck above them, so the term quarterdeck is not only the correct one, but I find it much more appropriate than the generally used "sundeck".

Like I said... you can call it the Promenade Deck or the Lido Deck for all I care. Just never heard a pleasure boat (not a ship) refer to a quarterdeck.


I recall often hearing the USN incorrectly refer to the quarterdeck as the fantail, and whenever we heard a pipe such as "... to muster on the fantail", it always got a laugh from us. In nice weather, we used to muster the crew on the quarterdeck for grog, and we assumed the U-alls were mustering on the fantail for iced tea. :lol:

I see... but you've misunderstood it seems. The "faintail" is the very aft of the ship... No where near the quarterdeck... literally hundreds of yards away. Usually that's where we'd muster our working parties for the day. I guess on those smaller Canadian ships the terminology blurs a bit. (jab)

It's all in fun Michael. I rode the HMAS Canbera into Perth many years back and was quite happy to tip back a pint at the end of the day. That's one thing I was convinced we were doing wrong in the USN :)

[Dawn Dreamer]

I see... but you've misunderstood it seems. The "faintail" is the very aft of the ship... No where near the quarterdeck... literally hundreds of yards away. Usually that's where we'd muster our working parties for the day. I guess on those smaller Canadian ships the terminology blurs a bit.

According to the Random House Dictionary, which I use here rather than a real English dictionary, the definition of fantail is given as ... "7. U.S. Naut. a. the part of a rounded stern extending abaft the aftermost perpendicular; a rounded counter. b. the area within this." With the exception of USS Ticonderoga, none of the USN ships in which I spent time had a fantail by definition. Yet they all mustered their hands there. :roll:


I rode the HMAS Canbera into Perth many years back and was quite happy to tip back a pint at the end of the day. That's one thing I was convinced we were doing wrong in the USN :)

We ofted discussed the dramatic differences in the behavior ashore between Canadian sailors and USN sailors. The first thing the US sailors looked for ashore was alcohol, and lots of it, while the Canadians seemed much less drunken and rowdy. :?

[SomeSailor]

With the exception of USS Ticonderoga, none of the USN ships in which I spent time had a fantail by definition. Yet they all mustered their hands there. :roll:

Spent many a year... on many a ship... Without exception... they all have fantails. Here's a pic I took on the fantail one night off just outside Victoria:

http://somesailor.homestead.com/files/Test_Cell_-_110_in_Burner.jpg


The first thing the US sailors looked for ashore was alcohol, and lots of it, while the Canadians seemed much less drunken and rowdy. :?

Actually... they're usually looking for was Canadian women... and then alcohol... but you're pretty close on that one. :)

(just teasin' ya of course... always fun to tease another sailor... Doug (GoAweigh) is also retired Navy and there are a couple other former squids on here as well... And a few Air Force and Marines so be careful there :D)



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