PLB Personal Locator Beacon Explained

[Paul L]

Originally Posted by Dockhead

That's right. Very spotty SAR coverage in the Carib. But even with first world SAR service -- note carefully that due to the procedure, it takes at least several hours, to get a response.

I'm with you on this. Eprib style PLBs are useless for MOB situations.

[Paul L]

Originally Posted by Kenomac

Understood. Do you know if an extra battery for the MOB1 is available and can be easily changed by the user? Is it possible to have a "practice battery," so the full charge in the beacons can be maintained?

" The DSC test should only be carried out a maximum of two times a year to
minimise battery consumption."
"The AIS/GPS test should only be carried out a maximum of three times a year to
minimise battery consumption."
"The MOB1 contains Lithium metal batteries for long operating life. Your battery must be
replaced either prior to the expiry date or after the MOB1 has been used, even if only
activated for a short period of time. Battery replacement must be carried out at an Ocean
Signal authorised battery replacement centre."

All from the download manual

[Singularity]

Originally Posted by Dockhead

I can't answer the question about WHICH devices it works on. I would think all of them. In any case, my own pretty old AIS transceiver certainly picks up AIS MOB signals, and these are shown as MOB! on my pretty old Zeus chart plotters.

I really thought/assumed that all these PLBs talk to local AIS. Not so. Must check your internal equipment (per routine). But if you're the type that likes to make sure that you can hear other peoples' MOB signals...might require some research into your equipment to see if you can. The MOB1 people don't list on their website [screenshot] which AIC receivers that are "suitable" (though presumably modern plotters).

This linked story makes for a very interesting a read. Looks like they had one of the little Mcmurdo devices get all excited about an adjacent magnetic field, bringing in the Coast Guard while highlighting other weaknesses in the entire system.

"How could a boat as elaborately equipped as Gizmo not see an active AIS MOB alert that was very nearby? How did I miss USCG calls on VHF, by phone, and even via Facebook? And right at the top of my list: How the hell did the well-stowed and untouched S10 turn itself on?"

[Paul L]

Originally Posted by Singularity

I really thought/assumed that all these PLBs talk to local AIS. Not so. Must check your internal equipment (per routine). But if you're the type that likes to make sure that you can hear other peoples' MOB signals...might require some research into your equipment to see if you can. The MOB1 people don't list on their website [screenshot] which AIC receivers that are "suitable" (though presumably modern plotters).

This linked story makes for a very interesting a read. Looks like they had one of the little Mcmurdo devices get all excited about an adjacent magnetic field, bringing in the Coast Guard while highlighting other weaknesses in the entire system.

"How could a boat as elaborately equipped as Gizmo not see an active AIS MOB alert that was very nearby? How did I miss USCG calls on VHF, by phone, and even via Facebook? And right at the top of my list: How the hell did the well-stowed and untouched S10 turn itself on?"

Any AIS receiver that isn't ancient should pickup the AIS Sart message sent out by the MOB1. There is more issues with the DSC signal. The FAQ lists VHF devicex that are knos to work

Which DSC radios are compatible with the MOB1?

Ocean Signal recommends using one of the radios from the list below with the rescueME MOB1. The following class D DSC radios have been tested in cooperation with the manufacturer and confirmed to receive the Individual Distress Relay call.

ICOM:
Current models; M91, M323, M423, M506
Older models; M411, M421, M505, M603

Simrad: RS90

Standard Horizon: The factory has confirmed the following models are compatible:

GX5500S
V4.xx (GX5500S only),

<GX2200/GX2150/GX2000>
V5.xx (ALL)
V4.xx (GX2150/GX2000 only)
V1.xx (GX2200 only)

<GX1700/GX1600>
V4.xx (ALL)
V2.xx (ALL)

<GX1300>
V2.xx (ALL)
V1.xx (ALL)

<GX1200>
V1.xx (ALL)

Class A DSC radios have always been able to receive this call and all models are believed to be compatible.

This list is not exhaustive and will be added to as more compatible models are confirmed.

Ocean Signal welcomes enquiries from other manufacturers wishing to have their radios listed here.

[Kenomac]

I just figured out a new way to recover and crane a MOB safely back onto a boat using a halyard which can be safely done by one person even in fairly rough seas.

‘Don’t know how to present it on this forum.

[Dockhead]

Originally Posted by Singularity

I really thought/assumed that all these PLBs talk to local AIS. Not so. Must check your internal equipment (per routine). But if you're the type that likes to make sure that you can hear other peoples' MOB signals...might require some research into your equipment to see if you can. The MOB1 people don't list on their website [screenshot] which AIC receivers that are "suitable" (though presumably modern plotters).

This linked story makes for a very interesting a read. Looks like they had one of the little Mcmurdo devices get all excited about an adjacent magnetic field, bringing in the Coast Guard while highlighting other weaknesses in the entire system.

"How could a boat as elaborately equipped as Gizmo not see an active AIS MOB alert that was very nearby? How did I miss USCG calls on VHF, by phone, and even via Facebook? And right at the top of my list: How the hell did the well-stowed and untouched S10 turn itself on?"

And then he wrote:


"In retrospect, I’m quite sure that I did get an AIS MOB alert, a very loud one, but I shut it down without looking at what it was!"

As I wrote, I receive AIS MOB alerts on my fairly old equipment, from people testing their equipment mostly. I received one today, in fact.



I guess that more or less all reasonably modern AIS boxes will receive these alerts, and alarm.

[Dockhead]

Originally Posted by Kenomac

I just figured out a new way to recover and crane a MOB safely back onto a boat using a halyard which can be safely done by one person even in fairly rough seas.

‘Don’t know how to present it on this forum.

Why not? Just start a new thread.

[Tillsbury]

Originally Posted by Kenomac

I just figured out a new way to recover and crane a MOB safely back onto a boat using a halyard which can be safely done by one person even in fairly rough seas.

‘Don’t know how to present it on this forum.

It doesn’t matter. However you present it a few posters will tell you how impossible or useless or irrelevant your idea is, and the rest of us will read it with interest...

[Kenomac]

Originally Posted by Tillsbury

It doesn’t matter. However you present it a few posters will tell you how impossible or useless or irrelevant your idea is, and the rest of us will read it with interest...

OK, I need to get some sleep prior to heading into work the third shift, look for it in about 6-7 hours with a link to this thread.

Ken

[Singularity]

Originally Posted by Dockhead

And then he wrote:

"In retrospect, I’m quite sure that I did get an AIS MOB alert, a very loud one, but I shut it down without looking at what it was!"

As I wrote, I receive AIS MOB alerts on my fairly old equipment, from people testing their equipment mostly. I received one today, in fact.

I guess that more or less all reasonably modern AIS boxes will receive these alerts, and alarm.

It took guts to write the article. Probably tens of thousands of airline passengers have been killed in the past by easily defeated safety systems (e.g. the normative practice of pulling the breaker on some alarm systems). Tens of millions of patients harmed as medical people "click through" alarm notification pop-ups. Accordingly, in those disciplines, certain "I really mean it" alarms were developed that cannot be easily defeated.

I suppose I'm naively disturbed that a MOB doesn't trigger some different type of alarm that's not easily clicked away. It's easy to say "pay attention" but that's just not how it always works...lots of things conspire to task saturate/distract/etc.

[Dockhead]

Originally Posted by Singularity

It took guts to write the article. Probably tens of thousands of airline passengers have been killed in the past by easily defeated safety systems (e.g. the normative practice of pulling the breaker on some alarm systems). Tens of millions of patients harmed as medical people "click through" alarm notification pop-ups. Accordingly, in those disciplines, certain "I really mean it" alarms were developed that cannot be easily defeated.

I suppose I'm naively disturbed that a MOB doesn't trigger some different type of alarm that's not easily clicked away. It's easy to say "pay attention" but that's just not how it always works...lots of things conspire to task saturate/distract/etc.

I think that's fundamentally not an equipment problem, but a procedures problem.

[s/v Jedi]

Reading this thread, I think not everybody understands the difference between a VHF radio receiving a DSC MOB signal and a (AIS enabled) VHF radio or AIS receiver/transponder receiving an AIS MOB signal.

These are two separate mechanisms. We used to have gadgets for each one separately, but now they have beacons that combine the two.

If a DSC equipped VHF radio receives a MOB signal, it will sound an alarm but it will also send a message to the chart plotter which then shows the MOB on the map.

If an AIS receiver gets a message from an AIS MOB device, it shows it just like any other AIS target but most modern AIS receivers understand it is a special MOB signal and use a special icon on the screen and sound the alarm. Chart plotters that display AIS targets will also show the MOB and most modern ones again understand it's a special target and act accordingly.

[slipaway]

Am not going to get into the debate over AIS beacon vs PLB for MOB...there are advantages (and disadvantages to both). Just wanted to point out an interesting article that addresses this issue: https://www.soundingsonline.com/voic...-ais-satellite (note the article uses EPIRB and PLB to mean the same system).

[Singularity]

Originally Posted by s/v Jedi

Reading this thread, I think not everybody understands the difference...

Thanks for this...I really muddied the water.

[Kenomac]

Originally Posted by Kenomac

I just figured out a new way to recover and crane a MOB safely back onto a boat using a halyard which can be safely done by one person even in fairly rough seas.

‘Don’t know how to present it on this forum.

Here’s the thread: MOB Recovery Technique - Cruisers & Sailing Forums