ACR EPIRB vs Resqlink PLB

[Wotname]

Originally Posted by CarlF

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In a liferaft, the PLB doesn't need to be held upright. The antenna just has to be out of the water.
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Interesting / surprising comment!
Do you have any factual justification for this belief?

[Wotname]

Originally Posted by CarlF

.........

You don't need a 48 hour battery because SAR knows your location in about 20 minutes. If the signal continues for a couple of hours, they've also plotted your drift and will keep that plot going without more signals. Unless you are in the 1% who sail in high latitudes or the most remote areas, a plane or chopper will reach you within 12 hours
.........

Presumably you are referring coastal North American waters.

For other cruisers please be aware there any parts of the trade wind ocean areas that aren't remote but are well outside a 12 hour response time and mostly outside any chopper range.

Additionally in south east Asia, SAR assets can be basic and in short supply.

That 48 hour battery could be quite handy!

[Wotname]

Originally Posted by a64pilot

Well, I guess I’m showing my age, ......

You are in good company and it never gets better

[JustCroozin]

Originally Posted by a64pilot

I haven’t article, but your correct the 121.5 signal would be for homing, the 406 is a data burst, and nearly impossible to home on.
Homing takes time, that is why the USCG and others will ask you for a long count and likely several if they are trying to DF your VHF.

However the satellites using I guess Doppler can triangulate a 40t signal, this is not DF or “homing” but they can get a rough idea as to location and I believe after several succeeding passes they can reduce the circle of error.

121.5 Mhz is the aircraft emergency signal frequency, so its still very useful to have it operating in EPIRBs as all aircraft flying overhead monitor it. We are always listening to this on our rescue craft as well, so any EPIRB activation nearby will squawk on our RDF and we'll start homing in on it, reducing the response time. The problem with the old system was that it could take several satellite passes before a position could be triangulated, which is a negative for non-GPS equipped EPIRBs as well. Depending on where you are in the world, it could take hours for a reasonable search area to be determined, as satellites pass overhead at varying frequencies and it may take several sat passes to get a fix on you.



GPS equipped EPIRBs cut the time down as your coordinates are known straight away, which is why anyone with an old EPIRB without GPS should hand it in and get a new one. The difference in accuracy is huge; 5km for non-GPS 406Mhz, down to better than 120m with GPS. If you've ever searched for someone in the water, you will know how hard it is to find them, especially in rough water and at night. If that person is no longer able to hold onto a PLB then it can become impossible, which is why I would never rely on a PLB alone in a marine emergency. I have one on my PFD, along with an AIS beacon, but they are for MOB situations, not for vessel emergencies.


As for keeping a PLB upright, all of my training has taught me that the antenna of PLB or EPIRB must be upright to be effective; throw it on the floor of your liferaft at your peril. The cord supplied with EPIRBs is there so you can attach it to your liferaft or still floating vessel and let it float upright.

[RUSTYNAIL]

To WOTNAME... I am glad to hear that they use the Rockwell/Collins direction finder in Australia also. We started using that in the USCG aircraft about 2007 and it quickly took the search out of 406 beacons. My first testing was with the Becker DF unit and it also worked perfectly on 406.025 MHz. We got over 100 nm locks at 20,000 ft alt with 406 df'ing. Helos did very well also. The 121.5 was very easy to attenuate the signal and caused lots of long searches if the EPIRB wasn't properly deployed or the antenna was not out in the open.The 406 signal is a 5 watt strong burst. I'm sure the PLB would get the same results if properly deployed. If I had unlimited funds I would have everything that previous captains had recommended. After 42 years working for the USCG, I'll stick with an EPIRB first.

[Quadrille in JB]

All of this great grraat collection pf wisdom convinced me. I cancelled my order for an ACR PLB and instead purchasied an ACRGlobalfix V4 EPIRB.
Thanks
Bill in Jensen Beach

[a64pilot]

121.5 did in fact used to be the aircraft ELT frequency, but as of years ago it’s not even monitored anymore.
I wouldn’t count on 121.5 for anything, it’s still there but almost no one is listening anymore.
If you happen to have an aviation handheld, 123.45 may get you someone, it’s the International BS frequency, a lot of aircraft when over water will have one radio tuned to 123.45, but it’s not guaranteed, and I don’t know if a hand held can reach an aircraft at 30,000’ even if it’s right overhead?

[Wotname]

Originally Posted by a64pilot

121.5 did in fact used to be the aircraft ELT frequency, but as of years ago it’s not even monitored anymore.
I wouldn’t count on 121.5 for anything, it’s still there but almost no one is listening anymore.
If you happen to have an aviation handheld, 123.45 may get you someone, it’s the International BS frequency, a lot of aircraft when over water will have one radio tuned to 123.45, but it’s not guaranteed, and I don’t know if a hand held can reach an aircraft at 30,000’ even if it’s right overhead?

Rest assured, an aviation handheld will easily communicate with an airliner at 30,000'. Aviation handheld's are typically 5W (similar to a marine handheld) and 30,000' is about 5 to 6 miles so that is well with the range of the radio. It is also perfect line of sight - rule of thumb, it you can see or hear an aircraft, you can probably talk to it with an aviation handheld . FWIW, the Tx power of a typical small general aviation aircraft fixed comm is only around 10W or less.

However, it should be noted that the 121.5 Mhz transmitter in modern EPRIBs and PLBs has been reduced to 50mW. It used to be much higher - greater than 100mW. I have forgotten the actual figure and am too lazy to research it .

The reduction of the 121.5 Tx power has allowed for more of the battery capacity to be available to drive other circuits in the beacon - GPS engines, strobes and so on. This has naturally reduced the range of the 121.5 homing signal but that is of course offset by the location accuracy available to SAR / RCC of the 406 transmitter (even without an embedded GPS chip).

[Wotname]

Originally Posted by RUSTYNAIL

...... My first testing was with the Becker DF unit and it also worked perfectly on 406.025 MHz. We got over 100 nm locks at 20,000 ft alt with 406 df'ing. Helos did very well also. The 121.5 was very easy to attenuate the signal and caused lots of long searches if the EPIRB wasn't properly deployed or the antenna was not out in the open.The 406 signal is a 5 watt strong burst. I'm sure the PLB would get the same results if properly deployed. If I had unlimited funds I would have everything that previous captains had recommended. After 42 years working for the USCG, I'll stick with an EPIRB first.

Yes, the current generation of the Becker DF units are excellent and are very price competitive compared to say Rockwell Collins (understandably) thus allowing more to be installed for the available dollar.

Just something to fill one's mind when tooling about in a life raft in some tropical far flung sea

[barryglewis]

We carry several epirbs, 1 is packed in the liferaft.

[Wotname]

Originally Posted by CarlF

......

In a liferaft, the PLB doesn't need to be held upright. The antenna just has to be out of the water.
.............

Originally Posted by Wotname

Interesting / surprising comment!
Do you have any factual justification for this belief?

In the absence of any further justification from CarlF, I would urge other readers to disregard his advice.

AFAIK, no manufacturer of PLB's support this assertion and as an ex RF professional, neither do I. However I'm always happy to be corrected if there has been new developments in antenna design .

You will get best results by keeping the PLB antenna vertical with a clear view of the sky and ideally sitting it on an horizontal piece of metal or foil. As someone once said, if you are down to your last chance, it had better be a good one.

[FlyingScot]

I think you should have multiple ways to communicate/seek help.

We have an EPIRB category 2. It's ACR iPro with the display. It is designed to activate when it gets wet, as long as it is not still held tight in it's bracket. It feels well made.
Why not a category 1? What part of my catamaran will be 6 feet underwater?
We mounted it within reach of the helm, just inside the sliding glass door.

We also have one ACR ResQLink+ PLB. I like it. The display model (Aqualink View) is too large IMO.

We recently obtained an Icom M93D handheld VHF with DSC. It seems well made.

We are now considering AIS MOB type devices. Anyone know of any that automatically activate when getting wet, as opposed to the typical activation with inflatable PFDs.

We also have a Garmin Inreach Explorer+.

If the situation warrants setting off one EPIRB, I'll be setting off everything. The more signals coming their way, the more likely they will take it as a serious situation and not a false alarm.

[paralog]

Originally Posted by CarlF

As others have mentioned, once you are swimming it doesn't really matter if your PLB sinks or you hold it wrong. Your chances of surviving hyperthermia the 4-6 hours until rescue arrives is vanishingly small. Fortunately, almost all EPIRB activations are from the boat or from a liferaft.

In a liferaft, the PLB doesn't need to be held upright. The antenna just has to be out of the water.

You don't need a 48 hour battery because SAR knows your location in about 20 minutes. If the signal continues for a couple of hours, they've also plotted your drift and will keep that plot going without more signals. Unless you are in the 1% who sail in high latitudes or the most remote areas, a plane or chopper will reach you within 12 hours

I believe anyone considering a EPIRB or PLB should also consider an InReach. In most situations, an InReach will get you rescued more quickly and more effectively than an EPIRB or PLB.

This is because over 95% of EPIRB and PLB signals are false alarms. Rescue efforts are delayed by hours while SAR tries to contact the people in the database. The two-way communication of the InReach usually allows immediate confirmation - as well as critical information for SAR such as number of people, nature of distress, and injuries.

That said, any piece of technology can fail - be it an InReach or an EPIRB. That's why I carry an EPIRB as a backup to the InReach.

The issue I would have with SPOT, InReach etc is that they are there to make a buck and as we know they can be here on day and gone the next with no backup so you could possibly find your self with no safety system.
Epirb and PLB is the ideal way to go but for me a PLB was the cheaper choice while coastal sailing but in the event I do go offshore It will be with and EPIRB and PLB. I have registered and changed registration information on quite few EPIRBs and this is one of the key things, keeping the information of the vessel etc up to date and the contact details correct. Time comes when the batteries expire and it is not really worth is getting new batteries as the technology has changed and now the newer EPIRbs give out a gps signal as well.