EPIRB versus AIS PLB

[Graham_Wright]

I thought this had been hacked to death but things change.

Naively, it seems to me that if you suffer a MOB, the PLB will allow you to find and hopefully recover.

The EPIRB, if attached to the MOB, will not.

This seems a compelling choice to go for the PLB.

What is wrong with this simple view?

 

[RichardS]

That's why we carry PLBs rather than an EPIRB but we're never more than 100 miles off the coast at night. If we were crossing oceans I would also have an EPIRB.

I think improved combinations of devices are becoming available since we bought ours so there might be better options now.

Richard

 

[lw395]

There are PLBs, which work by SARSAT and there are AIS MOB devices.
There are things which do both.
I've used the AIS only sort for locating divers, which is obviously not an emergency situation.
You can't home in on a basic PLB unless you have a 121.5MHz DF set and you will be alerting the coastguard etc.

 

[Graham_Wright]

My post references AIS PLB.

Will that not let me home in on the MOB?

 

[lw395]

My post references AIS PLB.

Will that not let me home in on the MOB?

In between taking phonecalls about 'isit another false alarm?' and warding off lifeboats and helicopters... provided your AIS and GPS work etc.
In the jargon, if it's not a SARSAT 406 Beacon, it is NOT a PLB. It might be an AIS MOB device or AIS Beacon.

This is an AIS/PLB:
seaangel.at

 

[bedouin]

I think there are good arguments for either.

For my own use I prefer the 406 because I often sail singlehanded or with a crew I would not trust to (be able to) pick me up again. For crew I would prefer them to have AIS ones (but I don't have any yet).

 

[prv]

My post references AIS PLB.

Will that not let me home in on the MOB?

It will - but your terminology will continue to confuse the whole thread and dilute the answers you seek, because "PLB" is generally understood to refer to a 406MHz SARSAT device.

An AIS MOB beacon makes sense for a boat with multiple crew, where those remaining on board can home in on the MOB and recover them. The remaining crew constitute the most immediately-available source of help, and if external assistance is needed they can call for it by VHF or PLB/EPIRB.

A PLB gives a singlehanded MOB a chance of rescue; an AIS beacon isn't a good choice because of its short range and lack of reception capability on all boats (even if suitable equipment happens to be fitted, crews may not recognise the alert or understand how to use it).

This choice - for crewed boats vs single-handers - is fairly well-understood and uncontroversial at this point.

EPIRBs are not relevant to the question, being generally too bulky for constant wear and not designed for it in any case. They belong to the boat rather than an individual and are either manually deployed or launched from a hydrostatically-operated housing.

Pete

 

[Graham_Wright]

My feeling is that offshore, a plb will be of no use as, by the time the system has wound into action, the MOB will probably be dead from hypothermia.
Having been involved in many MOB exercises, with a two man crew, the chance of keeping an eye on the mob is remote. There is just too much to do.
A position fix will help but drift devalues it. The slightest chop obscures a head very rapidly.

It seem to me, that an AIS signal and a DSC alert offers the best chance of recovery.

It would seem there is no avoiding both. The plb (AIS variety), would increase the chances of rescue by the crew and the epirb would provide a global back up.

It would all be different in range of the shore.

I believe the reason an AIS plb does not transmit on 406 is down to legislation referring to mode of actuation. Does not seem to be insurmountable.

 

[lw395]

My feeling is that offshore, a plb will be of no use as, by the time the system has wound into action, the MOB will probably be dead from hypothermia.
Having been involved in many MOB exercises, with a two man crew, the chance of keeping an eye on the mob is remote. There is just too much to do.
A position fix will help but drift devalues it. The slightest chop obscures a head very rapidly.

It seem to me, that an AIS signal and a DSC alert offers the best chance of recovery.

It would seem there is no avoiding both. The plb (AIS variety), would increase the chances of rescue by the crew and the epirb would provide a global back up.

It would all be different in range of the shore.

I believe the reason an AIS plb does not transmit on 406 is down to legislation referring to mode of actuation. Does not seem to be insurmountable.

IF IT DOES NOT TRANSMIT ON 406 IT IS NOT A PLB!

 

[Roberto]

At the last enquiry (a couple of weeks ago), the combined PLB/AIS at seaangel.at still needs -in the manufacturer s words- "12 to 18 months before getting approval".
As the product has been announced a few years ago (2016 IIRC), a reasonable question is will it ever be available.

 

[RichardS]

IF IT DOES NOT TRANSMIT ON 406 IT IS NOT A PLB!

Mine is called a PLB with AIS functionality. I've no idea what frequencies it transmits on but I assume that it's the sort of AIS/PLB that Grahame is referring to. It seems unnecessary to keep picking him up on his nomenclature as we all understand the question he is asking.

Richard

 

[ctva]

Mine is called a PLB with AIS functionality. I've no idea what frequencies it transmits on but I assume that it's the sort of AIS/PLB that Grahame is referring to. It seems unnecessary to keep picking him up on his nomenclature as we all understand the question he is asking.

Richard

Which make / model is it as I have never seen one? Interested to know.

As far as I am aware;

PLB / EPIRB are basically the same in that they alert MRCC via satellite and give position. They differ in their deployment method and battery life.

AIS MoB device transmits a VHF AIS signal which is line of site and receivable by all in range.

 

[ShinyShoe]

Graham

Perhaps be clear what you want it to do or specify a model.

 

[lw395]

Mine is called a PLB with AIS functionality. I've no idea what frequencies it transmits on but I assume that it's the sort of AIS/PLB that Grahame is referring to. It seems unnecessary to keep picking him up on his nomenclature as we all understand the question he is asking.

Richard

What make is that?
I assume it also has 406 functionality?
You can get locating device devices working on mobile phone bands, bluetooth, licence free and all sorts, but that does not make them PLBs in any maritime or useful sense.
You might as well say your mobile phone is an EPIRB, because you could be located by it in an emergency.

I have not taken much interest in the latest offerings in this market for a while, last I knew several manufacturers were very close to launching combined AIS-PLB devices onto the market. I know the chap who designed one of them quite well, but we've both moved on to different work since then. Thinking about it, it's a long time ago now, I've bought and sold several boats and a house in the meantime.

There are other man-overboard location systems which are neither AIS nor PLB based.

 

[requiem]

Mine is called a PLB with AIS functionality. I've no idea what frequencies it transmits on but I assume that it's the sort of AIS/PLB that Grahame is referring to. It seems unnecessary to keep picking him up on his nomenclature as we all understand the question he is asking.

I too would like to see some model numbers called out. To me, nomenclature is important, particularly with safety-critical devices. Just because it's electronic and people may be less familiar with the details doesn't lessen that; it's still akin to calling a halyard a sheet.

For example, if you don't know what your device transmits on, you have a potential problem. Suppose it only transmits on 121.5 and AIS but you're still thinking the MRCC get the signal "because PLB"?

 

[Graham_Wright]

Graham

Perhaps be clear what you want it to do or specify a model.

I think this post and its responses have led me to a decision.

If I have a MOB (or, in my case, a WOB) I believe I would have a better chance of recovering them alive with an AIS PLB than waiting for rescue services if I am more than a few miles from help. It seems that a 406 only PLB would not directly help me. However a PLB (it stands for Personal Location Beacon with only implied and historical modus operandi in reference to 406) with AIS would offer the best chance of finding the casualty. If it also transmits on 406 (we are all waiting for Richard's reply!), that would be the best of both worlds. Those I have seen, alert on DSC which may wake an off watch crew member and which could then be retransmitted to other vessels.

I am also driven to the conclusion I need an EPIRB for the possibility of the ship foundering or some other emergency not capable of being sorted alone.

Thanks for all the feedback.

 

[RichardS]

I think this post and its responses have led me to a decision.

If I have a MOB (or, in my case, a WOB) I believe I would have a better chance of recovering them alive with an AIS PLB than waiting for rescue services if I am more than a few miles from help. It seems that a 406 only PLB would not directly help me. However a PLB (it stands for Personal Location Beacon with only implied and historical modus operandi in reference to 406) with AIS would offer the best chance of finding the casualty. If it also transmits on 406 (we are all waiting for Richard's reply!), that would be the best of both worlds. Those I have seen, alert on DSC which may wake an off watch crew member and which could then be retransmitted to other vessels.

I am also driven to the conclusion I need an EPIRB for the possibility of the ship foundering or some other emergency not capable of being sorted alone.

Thanks for all the feedback.

Sounds like the same conclusion, more or less, that I came to as in post #2. My AIS PLB is on the boat so I've no idea which one it was as I bought it 6 years ago. It's probably due for new batteries or replacement and I've never used it.

Richard

 

[ShinyShoe]

I think your conclusion is probably right in your described use case. Best Chance of survival when (w)MOB from a well crewed boat, especially as distance from shore increases is likely to be recovery by own boat in which case AIS will be helpful.

But a satellite message feels useful (although - if you were in sat message only territory you'd want to be able to cancel it positively after recovery, so presumably sat comms,...)

Couple of extra thoughts -

Sounds like you sail as a couple. If you have a WmOB AIS may be your best hope. Without being sexist, what if you have a MOB - will she even be able to get you back on board.

While clearly going for a swim in the middle of the Southern Ocean is not a great plan, it's the kind of thing you try to prevent. I suspect more UK sailors die in local waters falling off dinghies or while boarding on a mooring etc. If you do that alone AIS may be unhelpful. (A DSC version *may* help but check how they really work - different country modes allow different alerts - I don't think UK allows direct to CG DSC alert)

I'm increasingly unconvinced of the need for a true EPIRB. Difference from sat PLB being - 48hrs Vs 24hrs of position data and automatically activation in water.

In reality you probably get more than 24hrs from PLB, if you are in the water that long you are are shark food. If you have the PLB on you, you don't need automatic activation unless you are unconscious in which case chances of survival are not great.

 

[Ohlin Karcher]

PLB's need the casualty to hold the flexible aerial up out of the water with one hand, which seems unachievable in many situations or for very long. You might need that hand for something else, and it would be numb soon anyway?
How long would that be needed to be 100% sure your distress had gone up?

 

[ShinyShoe]

PLB's need the casualty to hold the flexible aerial up out of the water with one hand, which seems unachievable in many situations or for very long. You might need that hand for something else, and it would be numb soon anyway?
How long would that be needed to be 100% sure your distress had gone up?

Mine is spring loaded. All you need is to hold the PLB upright. It wedges between the left and right part of inflated LJ very well