Latest thinking on AIS DSC personal beacons please?

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pcatterall

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Ocean Signal RescueME MOB1 is for example one that I am considering.
I want to take one out with me on my upcoming trip to the boat in Spain.
I want to test it with my NASA AIS and the DSC. If all is well I will recommend it to the regular crew
so we all have the same device and all know how it works and what to expect in the way of DSC AIS signals.

Just wondered what the current most favoured model was.

Thanks for your input
 
Are they not two separate things? An AIS SART broadcasts over the AIS channel. I believe they use message type 14 so you may want to check it can be received and displayed by your kit.

I think the DSC alert on the beacon simply sends a VHF DSC mayday as you would from a radio. I guess they can skip the bit where you select the nature of the emergency and just assume MoB.
 
I don't think the OP suggested the Ocean Signal RescueME MOB1 is a SART. It sends an AIS MOB signal and a DSC distress to provide two ways of alerting the crew that there's a MOB

I'm planning on buying a couple of these.
 
Hoolie said:
I don't think the OP suggested the Ocean Signal RescueME MOB1 is a SART. It sends an AIS MOB signal and a DSC distress to provide two ways of alerting the crew that there's a MOB

I'm planning on buying a couple of these.
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Just to the crew? i.e just to the MMSI of the boat? I thought it was a general DSC mayday.

I have to admit that as they're quite a few devices like this whose functionality overlaps I'm waiting for things to stabilise before purchasing.
 
lpdsn said:
Just to the crew? i.e just to the MMSI of the boat? I thought it was a general DSC mayday.

I have to admit that as they're quite a few devices like this whose functionality overlaps I'm waiting for things to stabilise before purchasing.
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Reading the specs (here http://oceansignal.com/products/mob1/#specifications) beacons sold in the UK are only able to transmit an Individual Distress Relay DSC call: that is a DSC call to the mother vessel radio only, not an All Ships Distress Alert. That seems to be because of OFCOM rules. So, the beacon automatically transmits an AIS distress signal, using a 972 MMSI that is built into the beacon plus a DSC call using the mother vessel MMSI which can be changed as required if moving from one vessel to another.
Given that limitations, I'd probably not bother with the DSC functionality unless I was able to source a beacon from a country which allows an All Ships DSC alert: but that might be blocked by the programming software which requires you to input an MMSI for the DSC function to work.
 
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Rule No 1. Fit a U bolt in the cockpit, fit jackstays and buy harnesses with one long a one short tether always clip on at night and in bad weather. We had a EPIRB and didn't need anything else. We also viewed life jackets as something you put on before getting into a life raft. Stopping a MoB we viewed as a priority.

One example of a MoB problem is we were sailing upwind up current in winds 20 to 25 knots off the Portuguese coast with big waves ands swells taking lots of water over the boat. It tore off the inflatable danbouy on the starboard stern quarter, even though much bigger than a head and with a flag on top it disappeared in four minutes, there was absolutely no chance of turning the boat in those conditions and finding it.
 
KellysEye said:
One example of a MoB problem is we were sailing upwind up current in winds 20 to 25 knots off the Portuguese coast with big waves ands swells taking lots of water over the boat. It tore off the inflatable danbouy on the starboard stern quarter, even though much bigger than a head and with a flag on top it disappeared in four minutes,
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..... and that is exactly why an automatic AIS beacon on the crew life jacket is worth considering - the location is easy to find, even if recovery thereafter is not trivial.
Nobody is suggesting these are instead of using harnesses. And “life jackets only when getting into life raft” is certainly a policy I don’t support on board.
Don’t forget that AIS MOB beacons have saved lives on offshore boats with 100% harness rules - whether due to harness breakages or human factors when been unclipped for a few seconds. Most of us are human and can make mistakes, this may help recover from a mistake
 
A lot of ais receivers are not able to recognize 972xxx mmsi as distress, that is the ais mob beacon target appears on the screens as a new target only, one has to click over it to read the "target details", where it shows "mob" as its name
During testing in France, the Cross/Mrcc saw the target appear on its screens about 10minutes after launch, with no indication of it being a distress signal
Also, after they were dropped in the water, the actual signal was sent on average 4minutes later, possibly because of gps fix delays.
In substance, they seem essentially useful only for the boat whence the person fell, *and* if people onboard knew someone fell overboard, hardly useful for a couple where one of the two is sleeping inside..
If things have not changed/ improved since, very very unimpressed with the device.
When singlehanding in coastal waters, I add my portable dsc vhf to the kit I have on me, which makes me look like a Michelin puppet :D
 
KellysEye said:
Rule No 1. Fit a U bolt in the cockpit, fit jackstays and buy harnesses with one long a one short tether always clip on at night and in bad weather. We had a EPIRB and didn't need anything else. We also viewed life jackets as something you put on before getting into a life raft. Stopping a MoB we viewed as a priority.

One example of a MoB problem is we were sailing upwind up current in winds 20 to 25 knots off the Portuguese coast with big waves ands swells taking lots of water over the boat. It tore off the inflatable danbouy on the starboard stern quarter, even though much bigger than a head and with a flag on top it disappeared in four minutes, there was absolutely no chance of turning the boat in those conditions and finding it.
Click to expand...

Thanks and, yes, prevention is better than cure. We do have the equipment you recommend but I requested views/opinions on the device rather than other safety options.
 
A friend of mine sells rechargeable torches. He had one returned that was less than a year old with the owner stating it would not hold its charge. He sent the torch to the distributor who said "No wonder. The battery is over 3 years old."
So one thing that puts me off buying a PLB/AIS beacon is the age of the battery. Bit like buying a lifejacket from a chandler only to find the firing capsule is out of date because it's been sitting on shelves either at the source, the distrubutor or the retailer.
So if I was to buy one I would want to check the dates before I did so. A large chandler may buy a significant stock in order to get the discounts but could take a significant time to shift the stock.
 
Just how effective are these beacons when used for real. Does the mob have to hold the beacon above their head? I'm pretty sure it will be close to useless in a submerged pocket. Do they float free on a lanyard? If so how good are they in a 2m sea? If they only transmit to the mother vessel, you immediately restrict the level of assistance from other vessels and aircraft
 
boomerangben said:
... ... If so how good are they in a 2m sea? If they only transmit to the mother vessel, you immediately restrict the level of assistance from other vessels and aircraft
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Get on to Ofcom about that. AFAIK the UK is the only country in the EU that has that restriction. All other countries allow broadcast distress signals.
 
boomerangben said:
Just how effective are these beacons when used for real. Does the mob have to hold the beacon above their head? I'm pretty sure it will be close to useless in a submerged pocket. Do they float free on a lanyard? If so how good are they in a 2m sea? If they only transmit to the mother vessel, you immediately restrict the level of assistance from other vessels and aircraft
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They float free and I guess with aerial out of water will transmit ok but improved if MOB can elevate it. The AIS is transmitted to all boats in the vicinity the debate is only about DSC being restricted to mother boat, however the mother boat could raise other craft via the radio.
 
boomerangben said:
Just how effective are these beacons when used for real. Does the mob have to hold the beacon above their head? I'm pretty sure it will be close to useless in a submerged pocket. Do they float free on a lanyard? If so how good are they in a 2m sea? If they only transmit to the mother vessel, you immediately restrict the level of assistance from other vessels and aircraft
Click to expand...

The idea is to mount them on top of the lifejacket bladder with the aerial pointing up:

reddingsvest+ais.jpg


They transmit in bursts, and the burst length is designed so that at typical wave periods you will rise over the top of a wave at some point during every burst. In McMurdo’s testing they actually found greater range in higher sea states because of the casualty being lifted up by the waves, carrying his aerial higher.

The AIS beacons broadcast to all, but the intention is to reach the mother vessel in particular because it’s the one that’s guaranteed to be nearby. These beacons were originally developed for offshore racing in the Southern Ocean, so there might not be another vessel for hundreds of miles.

The addition of DSC is still evolving - the design I looked at said the intended use case was to use the louder and standardised DSC alarm on the mother vessel’s radio since the plotter’s behaviour is less certain, hence the directed message. But of course once you have the ability to transmit DSC messages then thoughts turn to other possibilities.

Pete
 
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