MMSI question for MOB transponder, need fast answer

[dlochner]

There is zero confusion regarding what happens next with a satellite SARSAT device. None. Just saying.

So what DOES happen with this AIS thing and it’s duplicate MMSI when the Chinese fire drill begins? It calls your boat? What if you are singlehanding? What if mom is sleeping? What if everyone on board went overboard?

Suppose it triggers a DSC rodeo: Does the radio light up with the usual cast of characters asking for radio checks who somehow figure out that an emergency situation is ongoing and it involves your sailboat...and yes, it appears that your boat is motoring just fine? Does the USCG get involved, asking that all mariners be on the lookout for your 23’ vessel with leopard-skin topsides which has declared an emergency? What happens then? Does a radio committee form up ad hoc, would anyone have a clue that this isn’t a boat emergency, it is a MOB emergency? Suppose the radio committee had no AIS capability. Suppose the radio response committee had a ships radio with some add-on AIS screen with blinking dots. Remember, these are the radio-check guys, this is the modern USCG watchstander service model, and this is DIY rescue.

Ultimately there is no fool proof risk free system. Which system is right for you depends on where you are sailing and with whom you are sailing.

A personal AIS beacon is pretty worthless while crossing an ocean solo. An EPIRB satellite system is far better.

However, sailing in a relatively high traffic coastal area on a crewed boat will make the AIS based system a better system. The crew will immediately know a member has fallen overboard and the location will show up on the chart plotter virtually instantaneously. In addition every AIS enabled chart plotter within 5 miles will light up with a distress signal.

The Rescue 21 system set up by the CG has coverage out 20 miles from shore. It is able to receive distress calls from 1 watt radios at sea level. See the charts here: https://www.navcen.uscg.gov/?pageName=mtNds

In the Chesapeake and on the coastal waters most of us sail, an AIS is a much better choice.

Of course if you sailing in and around Point Nemo, an EPIRB is the way to go but it will still be a long wait for someone to find you.

 

[Gunni]

This is not a discussion about the Cospas-SARSAT, GMDSS marine rescue system, that is a different subject. But you should understand how it works before assuming that you have a better way to get a rescue.

I’m asking questions about this AIS / VHF rescue device that any user should be able to fully detail, since you are essentially running a DIY rescue. You don’t get do-overs in this business, and you need level-headed competent operators with the right equipment. I’ve yet to read a comprehensive description by anyone on how this personal AIS thing is going to be executed anywhere near 100% assurance.

And don’t kid yourself about who is coming to rescue you outside the warm confines of the U.S.A. Short of a few industrialized nations, very few places have a SAR capability, and none of them are using your DSC thingy. You will more likely see a commercial flagged to a nation party to Cospas-SARSAT on the horizon.

 

[Sailbaum]

I agree that every piece of safety gear is situation specific - and you don't get do overs. If I am solo, in the middle of an ocean, and I go overboard, a satellite PLB is my only hope - but frankly, I have no illusion that anyone will reach me in time. In my opinion, people who expect third party rescue in those circumstances are kidding themselves and should not go offshore.

On the other hand, if I am going offshore with a crew (as I have on several occasions), I will know them and trust them to be able to react in a MOB situation. The AIS/MOB beacons operate on a simple principle. They broadcast an AIS signal that there is an MOB and the location. In addition, they affirmatively call one pre-programmed MMSI to raise an alarm. This is not a dual MMSI issue- it broadcasts one signal (broadcasting MOB and location) - and calls another.

If the device is programmed correctly (and you can and should test it before leaving port), it alerts the vessel that the MOB came off of. Offshore, virtually by definition, that is the closest option for rescue. If "mom" (or other crew) is sleeping below, the MMSI call wakes her (them) up and they can commence immediate MOB measures, with a beacon on the chartplotter that updates the MOB position in real time directly to the boat. If I am 1,000+ miles offshore with a competent crew, that is my best - and in my opinion only - chance of rescue. Sure, I can also carry a Sat PLB - and if my crew can't get me, I might even turn it on so someone can find my body --- or not.

In my opinion when offshore, responsibility for safety starts on the boat - first with each individual, next with the crew. If - and only if - those fail do I consider third party rescue (if and when that's possible). The AIS/MOB beacons are consistent with that philosophy. Are they for everyone - certainly not. They are useless to singlehanders or those who venture offshore without competent crew. But with competent crew, they very clearly add a level of protection worth the nominal price.

 

[Gunni]

They broadcast an AIS signal that there is an MOB and the location. In addition, they affirmatively call one pre-programmed MMSI to raise an alarm.

So this device is setting an AIS target and uses the home vessel as a repeater to fire off a DSC alarm? How long / far does the MOB location stay current and accurate? Does the DSC lat/Lon show the boat or the MOB? Does the AIS / DSC target evaporate when the signal is lost, or is it durable? Does any of this function if your DSC radio shares an antennae with your AIS? (There will a lot of VHF radio squawking).

FYI: Like 90% of boat radios my boat has no active DSC, no DSC alarm, and my independent AIS (dedicated antenna), while connected to a cockpit MFD chart overlay has an alarm that would not wake mom if she was sleeping in the cockpit. I am out of the rescue mix until you (or the USCG) radio me with a pan-pan and tell me Uncle Sparky went in. This thing is a custom install for your boat, will maybe alert the USCG, a few DSC-enabled US boaters, and provide useable AIS targeting to me if I was X miles away. Anyone actually executed this thing in the fog of an emergency?

 

[dlochner]

So this device is setting an AIS target and uses the home vessel as a repeater to fire off a DSC alarm? How long / far does the MOB location stay current and accurate?

Almost. The device sends out an Emergency AIS signal that is received by all nearby active AIS receivers. The device sends a DSC signal the motherships DSC equipped VHF. The crew has to then hit the panic button on the VHF. That will broadcast an emergency signal to all other DSC equipped VHF radios including the CG's Resuce 21 service. The device sends out the AIS signal 2 or 3 times a minute. Presumably it updates the location each time.

Does any of this function if your DSC radio shares an antennae with your AIS? (There will a lot of VHF radio squawking).

Yes. The AIS data bursts are very short. AIS and VHF can share an antenna but they need a good antenna splitter so the two devices don't interfere with each other.

Like 90% of boat radios my boat has no active DSC, no DSC alarm, and my independent AIS (dedicated antenna), while connected to a cockpit MFD chart overlay has an alarm that would not wake mom if she was sleeping in the cockpit.

DSC has been a required feature in VHF radios for many years, so any newer VHF radio will have DSC capabilities. I suspect the number DSC equipped VHF radios is far greater than 10% of the boaters out there. However, if the radio is turned off, DSC obviously won't work.

When a DSC radio hears a distress call, the radio automatically switches to Channel 16 when the CG acknowledges the distress call.

This thing is a custom install for your boat, will maybe alert the USCG, a few DSC-enabled US boaters, and provide useable AIS targeting to me if I was X miles away.

It is not a custom install. The device is worn by the crew and if it used with an inflatable PFD it will automatically activate when the PFD inflates. The sequence is:

Crew falls overboard.
PFD inflates
AIS Locator activates, establishes GPS position, broadcasts AIS distress signal, broadcasts emergency signal back the the mothership.
DSC enabled VHF receives signal and sounds alarm
AIS receiver receives the AIS distress signal and displays the MOB position on the Chartplotter.
Onboard crew hit the panic button on the DSC enabled VHF and CG is notified of a vessel in distress.
CG acknowledges the distress signal and responds
VHF radio automatically switches to Channel 16 for standard voice communication
Crew steers boat to the AIS MOB target, other nearby boaters can also respond to the distress signal.

There are a lot of steps, but human error is limited to the first step (falling overboard) and hitting the panic button. Pretty simple.

The system will work best if the boat has an MMSI number and the VHF is connected to a GPS. The DSC distress signal will contain the boat's MMSI, the nature of the distress, and the GPS coordinates.

Here are 2 good references on DSC and Emergency Calling:
https://www.jamestowndistributors.com/userportal/document.do?docId=1110
http://www.boatus.com/foundation/dsc/player.html?WT.mc_id=400090: target=

If the VHF is not DSC enabled or if it has not been programmed with a MMSI number the system won't work. It is most effective when the VHF is connected to a GPS because the distress call sends out the boat's gps coordinates.

 

[jssailem]

I was on the boat about a week ago, fiddling with the boat and checking the radio for weather gettign ready to go for a sail, when the DSC alarm went off.

• Next thing I hear is the inquiry by USCG asking the skipper of the boat with the emergency to identify it self and the nature of the emergency.
  
• A minute or two later the skipper comes on the radio to the CG and states he is in the river channel off the Everett Port Docks. His engine has stopped. He is adrift.
  
• CG asks for any available boat go to the RipTide's aid. Within 5 minutes the skipper is back on the radio announcing that he has snagged the dock and that the emergency was over.
  
• Asks if the CG can help him tow the boat back to the marina launch ramp.
  
• A few minutes later the CG asks for the boater to declare if there had been any spills. Is there a sheen on the water?

The whole evolution was maybe 15 minutes.

I completed prepping my boat and headed out for a sail. As I passed the opening of the marina the skipper was on the radio in his boat. His crew was on the dock. Looked happy to be on the dock.

 

[Gunni]

Next thing I hear is the inquiry by USCG asking the skipper of the boat with the emergency to identify it self and the nature of the emergency.

That was one of the 90% of boaters who do not have their DSC set up. He can initiate a emergency signal with his panic button but the signal has less useful data than a voice pan-pan on Ch16.

 

[dlochner]

That was one of the 90% of boaters who do not have their DSC set up. He can initiate a emergency signal with his panic button but the signal has less useful data than a voice pan-pan on Ch16.

@Gunni I'm not sure I'm following your argument here. Are you saying that we shouldn't bother with AIS locator beacons because many boaters have not set up their DSC radios correctly? Or are you saying that those who have not set up their DSC radios correctly are being foolish?

If I set up my DSC VHF correctly and then use the panic button everyone with a DSC radio within range will get a message giving my GPS Coordinates, a broad descriptor of my emergency, and the boat's MMSI number. That information is logged in the VHF and remains accessible. The digital transmission of this information is far more accurate than trying to hear someone speak over the VHF while trying to copy down gps coordinates on a piece of paper.

If you stay in US waters, there is no cost to get a MMSI number and to connect the VHF to a GPS. Or better yet, spend a few extra dollars and get a VHF with an integral GPS and AIS.

 

[Gunni]

@Gunni I'm not sure I'm following your argument here.

What I posted in #24, the vast majority of DSC capable radios are not set up to operate correctly. That isn’t an argument, it is a fact provided by the USCG.

 

[LeslieTroyer]

Gunni I don’t care if most aren’t setup correctly, if mine is setup correctly it will correctly display on their display (radio and chart clutter if connected)

There is no setup required for a receiver of the DSC MOB info.

Your logic is like having a car with ABS in the 80 and turning it off because most other cars dot have it and they’ll crash into you regardless if yours is on or off.

 

[Sailbaum]

@Gunni proves the point here. Don't rely on external factors you can't control.
I agree, most DSC radios are setup wrong (including, apparently, Gunni's. According to him "Both my AIS and my ship's radio have their own MMSI" - if set up correctly a shipboard AIS should broadcast the same MMSI as its VHF).

With the AIS MOB device you rely primarily on your own resources. Your ability to program the device to call your ship and your crew's ability to rescue you. I'm comfortable with that.

 

[Gunni]

Gunni I don’t care if most aren’t setup correctly, if mine is setup correctly it will correctly display on their display (radio and chart clutter if connected

Good, then we can dispense with all this talk of DSC as some mulitiplier to your rescue. You are running a DIY rescue using an AIS device and some theory that other people have chartplotter AIS and know how to work a DSC radio. Hope you find your MOB before they drift out of your range.
As someone who has actually participated in a real EPIRB SARSAT response, there are much more assured ways to get your MOB back. The PLB is a real good one.

 

[LeslieTroyer]

If a DYI gets me out of the water faster than the CG can respond to the DSC MOB I’m all for it. I’ve been been sailing prams and submarines before a race. The rescue boat didn’t see. I was in the water maybe 10 minutes before a T-bird daysailing plucked me out of the water. I don’t think I have ever been as cold before or after. The water here kills you and the difference between starting a rescue immediately vs waiting for a 496 signal to filter thru a bunch of folks miles away from me is just too long. You may have different water and different needs so don’t think one solution is superior in all cases.

I’m done with this thread.

 

[dlochner]

What I posted in #24, the vast majority of DSC capable radios are not set up to operate correctly. That isn’t an argument, it is a fact provided by the USCG.

Do you have a reference for that fact?

 

[Gunni]

The survival rates for MOB are not good. I have done two in both cases conditions were optimal, daylight, clear conditions with a full crew on deck. Everyone was back on deck in minutes using traditional MOB practiced protocols. In the dark, open ocean, stormy, skeletal watches the chance of recovering people are real low. That is why everyone is wearing a harness and tether. We practice MOBs with a seat cushion float. So every watch wears a satellite PLB and lanyards a handheld VHF. The instructions are simple and clear - go in the water, light up channel 16, no answer in one minute, light up the PLB and await instructions, stay calm. By the way, the response time from satellite emergency trigger to a coast guard pan-pan in the US is just as quick, if not quicker that whatever the DSC thing is capable of.

 

[Gunni]

Do you have a reference for that fact?

Yes.

 

[Ward H]

Very interesting thread. While my current sailing area and style would not benefit from such a system, this may be in my future as I expand my horizons.
Thanks Dave for the detailed explanation.

It is not a custom install. The device is worn by the crew and if it used with an inflatable PFD it will automatically activate when the PFD inflates. The sequence is:

Crew falls overboard.
PFD inflates
AIS Locator activates, establishes GPS position, broadcasts AIS distress signal, broadcasts emergency signal back the the mothership.
DSC enabled VHF receives signal and sounds alarm
AIS receiver receives the AIS distress signal and displays the MOB position on the Chartplotter.
Onboard crew hit the panic button on the DSC enabled VHF and CG is notified of a vessel in distress.
CG acknowledges the distress signal and responds
VHF radio automatically switches to Channel 16 for standard voice communication
Crew steers boat to the AIS MOB target, other nearby boaters can also respond to the distress signal.

There are a lot of steps, but human error is limited to the first step (falling overboard) and hitting the panic button. Pretty simple.

The system will work best if the boat has an MMSI number and the VHF is connected to a GPS. The DSC distress signal will contain the boat's MMSI, the nature of the distress, and the GPS coordinates.

 

[dlochner]

Yes.

Thanks. Here's a take home message:

As Kunz at Furuno points out, the primary benefit of DSC — distress calls at the push of a button — is essentially intangible. Hayden at the NMEA agrees, saying that American boaters in general are not very safety-conscious. Our boaters don’t get up in the morning thinking that today is the day they might need rescuing.

The manufacturers and NMEA do need to get their act together on making integration easier. I was one of those with a DSC VHF that had an MMSI number but was not connected to a GPS because I couldn't figure out how to make it work. NMEA 0183 was too confusing.

My current VHF has a gps and AIS receiver built in. All I had to do was program the MMSI number which was quite easy. I have a separate AIS transponder that is integrated with the MFD. A bit of belt and suspenders approach. One of the reasons I bought the radio was to have the ability to contact commercial vessels via DSC. If I see a ship that I need to contact all I have to do is select the ship on the AIS list and press call. They will get a DSC alert that is automatically logged on their radio. From what I"ve heard commercial boats are more likely to respond to a DSC call or a call using the vessel's name. It is easy to ignore a hail to "the big ship over there".

While I appreciate your concerns about the low level adoption level and the desire to notify the authorities quickly, for the sailing I do the AIS based locator is a better system. The boat that is most likely to rescue me is my boat and on most days she can get there quicker than any CG boat. That another nearby vessel might also be notified and respond to an emergency is a bonus.

 

[Gunni]

You have all he AIS gear you need to identify commerials by name and make a call to the bridge on Ch13. Which makes more sense than getting through the yip-yap on Ch.16 with DSC. Or you could simply call out ‘commericial vessel off location X, bearing YYY degrees, this is the sailing vessel Z, bearing YYYdegrees’ and wait for the pilot to respond. I have NEVER had a pilot not respond. If a vessel does not respond to a hailing call, switch to Ch. 16 and be a bother to them! Keep it professional and classy, but know that that the CG watchstander is monitoring. My theory is their boating expertise ended with the boat bill of sale. Recently I have begun insisting that all crew learn how to properly make and receive VHF calls. Surprising how many people are shy of the radio. So they practice.

Boaters in general need to step up their game in regards to radio protocol and communications. I will often hail a boat that is behaving erratically just to see if they are standing a radio watch. Most are not. If they have an AIS signature, I will call it, for the record. Then you have the guys like John experienced. They don’t really have a true emergency, they have a panic attack and hit the red panic button, tie up the radio and the CG watchstander for half and hour, eventually fix themselves. This goof then comes back and wants the CG to give them a tow. Hilarity! What should have happened is the guy got himself a boarding inspection and a citation for all the other loose ends aboard.

 

[dlochner]

Which makes more sense than getting through the yip-yap on Ch.16 with DSC.

One of the goals of DSC was reducing the nonsense on 16. When a call is made to a vessel with DSC a reply channel is included. Many (all?) radios upon receiving the DSC call will then change to the reply channel.

Take a look at the link I provided earlier to the BoatUS presentation. It goes through the whole DSC system in great easy to understand detail.