Best signaling devices from the searcher’s point of view - update

[tursiops]

Still waiting reply from Ryan. He said a couple days ago that he would need to check that info with the Nautilus Lifeline engineers and would get back to me ASAP. It's now weekend, so I won't expect a reply until Monday at the earliest.

All GPS receivers work pretty much the same way. They listen for the signals from several GPS satellites and triangulate from those signals. The location provided by the Doppler shift from a transmitted signal (from a PLB, for example) is less accurate and is not a "GPS" position.

 

[Rred]

From the Nautilus "2" manual?
It is NOT A PLB. A PLB is generally defined as being a junior version of an EPIRB. The PLB usually is smaller and has half the battery life. Both transmit a 406MHz signal to the COSPAS SAR/SAT program, which monitors for distress transmissions.

The newer model Nautilus is a marine radio. While it has a standard GPS receiver in it, and it uses that to determine where it is, it does not "talk" to any satellites. Instead it uses the standard AIS DSC(marine VHF) local radios, and it broadcasts a LOCAL signal that nearby vessels should pick up.

One system is local. The other is international, with a global infrastructure.

If you are in an area that is not infested with boaters who have their VHF radios turned on, or commercial traffic who may be required to have it on, the new Nautilus will not help you. You'd need a real PLB, or an EPIRB, for that.

While most modern GPS receivers can acquire a position lock in half a minute, also be aware that they need a good sky view. If the satellites are low to the horizon and you are surrounded by mountains? Not so good, not so fast. If you have taken a plane flight, and the receiver was last turned on 1500 miles away? Eh, yeah, it will take longer because it is looking for satellites in the OLD location. So, you might want to turn it on and let it settle down after your flight. And wherever you are it doesn't REALLY get a good signal lock until it has seen the refresh signal on the GPS system, which is only passed to the satellites once every 17 minutes. So, for EPIRB and PLB, leave it on once you turn it on. For AIS systems? If you think there's no shipping in the area...maybe save it.

 

[Wingy]

When you want to know if there is shipping in the area - check AIS - MarineTraffic: Global Ship Tracking Intelligence | AIS Marine Traffic

Looks like the area is fairly well covered - but - zoom in around Ambon and Banda Islands for those of us having done/doing Banda Sea Crossings MarineTraffic: Global Ship Tracking Intelligence | AIS Marine Traffic

Note your best bet would be if Mermaid and the other (presumed) dive boat have all their equipment on, are on board not out with divers in the water and your EPIRB is heard. Theyre still a fair few miles away and as Rred mentioned...while it is called real time tracking, you are at the mercy of satellites.

Note I discounted the two freighters in the area because while they likely would have GPS on...its difficult for a bulker to participate in a search for a diver for many reasons. Size being the main one....economics also seems to factor in somewhere down the line.

 

[Rred]

"Note your best bet would be if Mermaid and the other (presumed) dive boat have all their equipment on,...and your EPIRB is heard. ...while it is called real time tracking, you are at the mercy of satellites.
"
No. No other boats can or will hear your EPIRB or PLB. None. Only the satellites here that, and then the call goes out to SAR assets, who MAY also contact shipping in that area by VHF radio or other means. But the direct EPIRB/PLB signal does NOT reach local craft.

That's what the other system, the Nautilus "2" is for. Using AIS/DSC, it will not reach the satellite rescue system at all, but it WILL directly reach local shipping.

Both types of equipment will use a GPS signal to determine their position, but even if they are a hundred yards off, the alert will go out. Degraded accuracy is usually not an issue.

It should be noted that GPS is NOT always a reliable position source. Within the US and other countries, military and government authorities routinely put out advisories that they will be "affecting" the system from time to time with testing, sometimes killing it for hundreds of miles.

There are also a fairly large number of intentional and accidental GPS spoofs and hacks every year (hundreds to thousands, the numbers are not easy to find) and growing worse, as various folks find reasons to locally shut down GPS for their own purposes.

So, if I were a pirate in Malaysia or Indonesia...I could scramble the positions of local shipping, making it harder for them to call for help. This is also a fairly dangerous game to play, as the military said twenty years ago "We have antiradiation missiles. You turn on the jammer, we push the button, you go away."

 

[CWK]

One system is local. The other is international, with a global infrastructure.

I would always expect local SAR to show up. The probability of the international Compas-Sarsat guys showing up to fish you out of the water is probably about 0.0000000000000000000001%

If you are in an area that is not infested with boaters who have their VHF radios turned on, or commercial traffic who may be required to have it on, the new Nautilus will not help you. You'd need a real PLB, or an EPIRB, for that.

If you use a PLB, local SAR will be alerted by Compas-Sarsat and your dive boat/resort should also alert local SAR as part of their lost diver protocol. If you use a MRG, local SAR will be alerted by your dive boat/resort as part of their lost diver protocol. In terms of having a local SAR operation initiated, it should not matter whether you use a PLB or SAR.

If you use a PLB no local boaters or commercial traffic will be alerted. If you use the MRG, local boaters and commercial traffic with AIS enabled marine radios will be alerted. The MRG offers the possibility of rescue by local boat traffic, the PLB does not.

In order for local SAR to find your GPS location and avoid an unexpected meeting with submerged reefs, their boats will almost certainly be fitted with a chartplotter which is the electronic equivalent of a paper based nautical chart. From Wikipedia (Chartplotter - Wikipedia):

"A Chartplotter is a device used in marine navigation that integrates GPS data with an electronic navigational chart (ENC).

The chartplotter displays the ENC along with the position, heading and speed of the ship, and may display additional information from radar, automatic information systems (AIS) or other sensors."

Irrespective of whether you use a PLB or MRG, you depend on local SAR to fish you out of the water. The question that is pertinent is whether local SAR has AIS enabled marine radio or AIS enabled chartplotter. AIS is the platform used by mariners for man overboard situations. I believe that, even in the third world, SAR boats will have AIS enabled marine radio or AIS enabled chartplotters.

 

[Wingy]

You are absolutely correct Rred - this is what happens when you post after a night with a household full of twenty year olds. I should have posted they would be your closest boats that could potentially be directed to you. When we sunk off Hillary's a Qantas jet flying overhead picked up our Epirb signal, contacted Canberra who contacted SAR Perth who turned up slightly after channel 7 did.

 

[Dan]

When you want to know if there is shipping in the area - check AIS - MarineTraffic: Global Ship Tracking Intelligence | AIS Marine Traffic

Looks like the area is fairly well covered - but - zoom in around Ambon and Banda Islands for those of us having done/doing Banda Sea Crossings MarineTraffic: Global Ship Tracking Intelligence | AIS Marine Traffic

Note your best bet would be if Mermaid and the other (presumed) dive boat have all their equipment on, are on board not out with divers in the water and your EPIRB is heard. Theyre still a fair few miles away and as Rred mentioned...while it is called real time tracking, you are at the mercy of satellites.

Note I discounted the two freighters in the area because while they likely would have GPS on...its difficult for a bulker to participate in a search for a diver for many reasons. Size being the main one....economics also seems to factor in somewhere down the line.

I have Marine Traffic app in my iPhone. As mentioned in page 8, post #78, I found BASARNAS' boats are equipped with AIS. Best signaling devices from the searcher’s point of view - update Whether one of the boats will be there to search for you after you launch your MRG's alert, that's another story that I'd like to know.

There are actually several liveaboards that have AIS in Indonesia. Besides Mermaid, Blue Manta that I plan to go to Banda next year, also has AIS.

 

[Dan]

Anyway, when you are lost at sea, it’s better to have PLB & MRG to send alert signals to every possible directions (up to the SAR satellites or to boats with AIS / DSC capabilities) than not having any of them and hoping for a boat to pass by & see you floating.

 

[Wingy]

Assuming they have their call signs turned on

 

[Dan]

I emailed Max Hand, Operation Manager of White Manta Diving to verify the Blue Manta call sign and able to track the boat whereabouts.

I can’t find any Mermaid boats, however. What are their call signs / MMSIs?

When I come on board the Blue Manta next year, I plan to discuss MOB situation with the captain & test my MRG signal with the boat.