Does anyone actually use DSC?

[loneshark64]

I have only used it once buddy boating .But I specifically got it and the MMS I number so that When I bring inexperienced guests on if I were to get incapacitated they can just push the red button. I always include that as part of my safety briefing along with basic instructions about how to use the VHF radio.

[Nepidae]

DSC is a tool that can be useful, helpful and was developed for emergencies.

MMSI is also a tool that can be useful, helpful and was developed for identification.

Wikipedia is also a tool that can be useful, helpful. Here is what Wikipedia has to say about both; Digital selective calling or DSC is a standard for transmitting pre-defined digital messages via the medium-frequency (MF), high-frequency (HF) and very-high-frequency (VHF) maritime radio systems. It is a core part of the Global Maritime Distress Safety System (GMDSS).

Further; DSC was developed to replace a voice call in older procedures. Because a DSC signal uses a stable signal with a narrow bandwidth and the receiver has no squelch, it has a slightly longer range than analog signals,[1] with up to twenty-five percent longer range and significantly faster.[2] DSC senders are programmed with the ship's Maritime Mobile Service Identity (MMSI) and may be connected to the ship's Global Positioning System (GPS), which allows the apparatus to know who it is, what time it is and where it is. This allows a distress signal to be sent very quickly.[1]

Often, ships use separate VHF DSC and MF/HF DSC controllers. For VHF, DSC has its own dedicated receiver for monitoring Channel 70, but uses the main VHF transceiver for transmission. However, for the user, the controller is often a single unit.[1] MF/HF DSC devices monitor multiple distress, urgency and sécurité bands in the 2, 4, 6, 8, 12 and 16 MHz bands. At minimum, controllers will monitor 2187.5 kHz and 8414.5 kHz and one more band.[3] However for automated monitoring a second, receive-only antenna is often needed (especially on non-commercial leisure boats) since a separate tuner is used apart from the main one;[4][5] this is separate from programming radios to monitor user-defined DSC frequencies (which would use the main antenna).

More; When sending a distress signal, the DSC device will at minimum include the ship's MMSI number. It may also include the coordinates if radio is connected to GPS system and, if necessary, the channel for the following radiotelephony or radiotelex messages.[3] The distress can be sent either as a single-frequency or multi-frequency attempt. In the former, a distress signal is sent on one band and the system will wait up to four minutes for a DSC acknowledgment from a coast station. If none is received, it will repeat the distress alert up to five times. In a multi-frequency attempt, the distress signal is sent on the MF and all the HF distress frequencies in turn. As this requires retuning the antenna for each sending, without waiting for an acknowledgment, a multi-frequency attempt should only be done if there are only a few minutes until the ship's batteries are under water. As the distress message can only be sent on one of the bands, many ships and coast stations may be listening to a band without the message, and will after five minutes relay the distress signal to a coast station.[8]

Distress calls can be both non designated and designated. The latter allows one of ten pre-defined designations to be sent along with the distress signal. These are "abandoning ship", "fire or explosion", "flooding", "collision", "grounding", "listing", "sinking", "disabled and adrift", "piracy or attack" and "man overboard".[8] To avoid false distress alerts, distress buttons normally have protective covers, often with a spring-loaded cover so two hands need to be used simultaneously. Alternatively, some devices have two-button systems.[9] Operators are required to cancel falsely sent distress alerts with a transmission on the channel designated by the distress signal.[10]

A coast station which receives a DSC distress alert will wait 2.75 minutes prior to sending an acknowledgment to allow other vessels in the nearby area to receive the alert. This helps shore stations narrow down where a vessel without GPS is located. The sending device will then both stop repeating the alert, and tune to the designated channel for the distress message to be sent. Ships receiving a distress alert who are outside coast station range or do not receive an acknowledgment, are required to relay the distress alert by any means to land.

And finally; The priorities for communication are, Distress, Urgency, Safety and routine. A Distress DSC call is called an Alert. Urgency, Safety and routine are called Announcements.

Class A VHF's, used on commercial ships, have the ability to send distress, distress relay, all ships urgency, all ships safety, individual, group, geographic area and telephone alerts/announcements on DSC channel 70 (Digital channel reserved for DSC only.). Class D VHF's, used for most leisure vessels, can send distress, all ships urgency, all ships safety and individual alerts/announcements on VHF channels on DSC channel 70. On both class A and D you can be directed to Ch 06, 08, 72, 77 or other simplex channel for the follow up RT (radio telephony [voice]) call. Class D has only one antenna and thus can only watch Channel 70 when not transmitting. For routine alerts, which are used to establish communication with another station on a working channel, the receiver acknowledges to confirm that communication can be done on the appropriate channel.[11]

While there are reserved frequencies for distress HF DSC calls, there is no prohibition against broadcasting non-distress, "routine" calls on other DSC-designated frequencies, which are defined in ITU.

Now, MMSI is; A Maritime Mobile Service Identity (MMSI) is a series of nine digits which are sent in digital form over a radio frequency channel in order to uniquely identify ship stations, ship earth stations, coast stations, coast earth stations, and group calls. These identities are formed in such a way that the identity or part thereof can be used by telephone and telex subscribers connected to the general telecommunications network to call ships automatically.

Check Wikipedia and reference MMSI to get a lot more info.

You asked.

Google sometimes, has a wealth of info. Try it out.

Stay safe & healthy out there.

[bobgarrett]

Yes, I have used it to contact boats we know within our club and also to call ships when necessary using their MMSI number - and have found that more reliable than a call on Ch 16.

[Sailmonkey]

Originally Posted by Happ

It’s called AIS! Yes I use it every time I leave the dock. I was sailing back from Annapolis and a 40’ powerboat was going along at about 7 knots. I saw them on AIS hailed them and he altered course. AIS gives the boat’s name, speed and direction. Also how close you will come to other boats.



You need to know what you own and how to use it. A GPS does you no good if you don’t know how to use it.

AIS is not DSC.....just to be clear.

[Joh.Ghurt]

Originally Posted by Sailmonkey

AIS is not DSC.....just to be clear.

True, but the beauty is the combination, when you can initiate easily a DSC call from your AIS. I don't see myself entering MMSI on the VHF via the fly-wheel except in dire need, but from the AIS target list, it's just a button-press away.

I guess this is the most common way to make DSC-Calls and it has the biggest chance to make DSC used more.

[Sailmonkey]

Originally Posted by Joh.Ghurt

True, but the beauty is the combination, when you can initiate easily a DSC call from your AIS. I don't see myself entering MMSI on the VHF via the fly-wheel except in dire need, but from the AIS target list, it's just a button-press away.

I guess this is the most common way to make DSC-Calls and it has the biggest chance to make DSC used more.

That’s true.

This also the only way I’ve used DSC, other than scrolling in the uscg radio check mmsi...then screwing up the save function!

[CyKlop]

background: On rare occasions, when we all know how to operate DSC, our sailing club may make DSC calls. Outside of that, never have used it with anyone.

However...

If my radio and chart plotter were talking to each other such that I could pick out a boat on my chart plotter and say, "call THAT one" and if an incomming DSC call would light up the originating boat on the plotter, that might increase the amount of DSC use.

[David Mathis]

In my many years of boating, only one DSC call was received. It was a windy day with very few boats out due to the sea conditions. A panic call was overheard calling USCG but they did not have a boat in the area. Since the radio signal was strong, it was obvious that the boat in distress was not more than a few miles away although we couldn't see any other boats due to wave height. I made VHF contact with the boat and learned that a person was overboard without a PFD or any other type of flotation and the wind had blown the boat far from the MOB. The person in the boat could not get it started and was unfamiliar with boating. The person was instructed to push the red button on the radio and hold it down for at least five seconds or until it beeped. It worked like magic; our plotter showed the exact position of the boat and logic dictated that the MOB would be directly upwind. We headed there as fast as practical given the wave conditions. As we neared the location, my son went on deck to look for the person in the water. Soon he yelled to turn hard left then within a few seconds, dove over the rail. The MOB was recovered in a totally exhausted condition. My son (a former certified life guard) said that the MOB was going down just as he dove into the water for the rescue and indicated that within another minute he would have drowned. Due to the wonders of DSC, the MOB is alive.

Don't discount DSC because calls haven't been received. We've been paying fire district taxes for years but haven't yet needed the fire department to respond to a fire at our house.

[Jim Cate]

Re use of DSC by commercial vessels: While nothing like the English channel or other extreme traffic areas, the East coast of Australia has a fair amount of ship traffic, and we interact with them on a regular basis. AIS has, of course, made this easier and much safer, both for them and for us. I have noticed that despite the availability of DSC to the big guys, when they need bridge to bridge comms, they seem to use calls on 16, switching to 06 rather than DSC. Of course, I wouldn't hear the DSC calls, but I do hear enough voice calls to be sure that this is still a common usage.

Jim

[torrmundi]

Originally Posted by B_Hunter45

Usually DSC is used with AIS system when you get the mmsi number from the AIS system. If you do not have AIS then dsc is almost useless.

It is useful for groups of boats, e.g. a rally or smaller group, with or without AIS, as long as the MMSI’s of the boats are pre-shared. I also put our MMSI on our boat card.

[torrmundi]

Originally Posted by CyKlop

background: On rare occasions, when we all know how to operate DSC, our sailing club may make DSC calls. Outside of that, never have used it with anyone.

However...

If my radio and chart plotter were talking to each other such that I could pick out a boat on my chart plotter and say, "call THAT one" and if an incomming DSC call would light up the originating boat on the plotter, that might increase the amount of DSC use.

B&G Zeus 2 (and 3, I guess) do exactly that with Simrad radios. It is very easy, and I have used it.

[Kamen]

Originally Posted by torrmundi

B&G Zeus 2 (and 3, I guess) do exactly that with Simrad radios. It is very easy, and I have used it.

All Navico brands do it. Also "buddy tracking", which sends position polling requests periodically and plots the other boat on your chart.

[Donald Bryden]

I've seen and used DSC to hail friends on other boats. Rather than calling on voice VHF hailing frequency and either talking on the hailing frequency as some do, or agreeing to switch to a referenced frequency where half the boats and all the thieves in the area follow to eavesdrop, DSC can be used to alert a target vessel and give a frequency for a meet. No one is disturbed by the process and privacy of conversation while not guaranteed is improved. Also, as has been mentioned, when hailing an AIS target has not worked, sending a DSC that sets off an alarm on the bridge is the next resort.

[Nicholson58]

We use the DSC function for hailing friends to keep the conversation somewhat private.

If you live aboard and develop a large circle of friends it is very useful

[armand.seguin]

Originally Posted by BillKny

I know how DSC on a marine VHF works, it is set up on my radio, I have tested it.

With the exception of a few (always false alarm) DSC distress calls NEVER has anybody placed a DSC call to my radio.

NEVER have I placed a VHF DSC call to anybody else’s radio.

NEVER have I talked to anyone who has actually placed a DSC radio call, or received one.

NEVER have I been in a real world situation where I thought, “Gee, DSC would really help right here...”

Am I just not one of the cool people who hang with the “in” crowd? Or is this a VHF radio feature that has never received any actual user traction?

Is there a broad base of use in the commercial shipping world I have just never heard of?

BillKny,

The DSC to the USCG is totally good and glad to have it. And, while the basic functionality is built in to contact a group, etc., the interface to do so totally sucks. That is why very very few use the "capabilities." While a tad unfair, think of what a cellphone can do....without even a manual supplied!! I say unfair as VHF radios likely sell a comparative handful as compared to cellphones in the billions.
The Cortex unit by Vesper Marine takes the VHF (and other features) takes VHF calling to another level. Like, you touch a boat/ship on the screen and call them!

Armand