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

[Dan]

Time is NOT of the essence in relation to being RESCUED and being found ALIVE. In this instance, English is of the essence. By defination, if you are RESCUED, you will be found alive, instead of dead. You may not survive long after rescue (because of hypothermia, dehydration or other factors) but that is another matter.

Right. English as my second language, will always be my problem, but you know what I meant. As I mentioned earlier in the previous posts, the sooner they would find me, the higher my chance would be for being rescued than recovered.

I don’t expect myself to be found alive after 3 days lost at sea. So, I don’t plan to carry safety gear, that I’d hopefully never use (knock on wood), excessively. Streamlining vs Christmas tree.

I originally carried a 500mL water bottle & foldable snorkel in BCD pocket. I had to remove & replace them with MRG, Dye Marker, glow stick, leash & strobe. I figured that I could survive floating at sea for a day without water & snorkel.

 

[Dan]

I am neither a statistician nor an actuary so my probability estimates may not be correct to even one decimal place, nevertheless I find that ball park figures assist me to think of the situation. Let me elaborate on some of the probability estimates that I think about.

Probability that a diver will be involved in a boat seperation incident and SAR is called: 0.2%
1% (probability of being involved in a boat seperation incident in your lifetime) x 20% (probability of not being found in the initial search resulting in a call to SAR) = 0.2%. The probability of SAR finding you if you do not have a PLB or MRG is probably nearer 0% than it is to 100%. Therefore this approximates the probability that you will be floating in the ocean thinking, "I can see you searching for me, but you can't see me."

Probability that a diver with an electronic beacon is involved in a boat seperation incident in which SAR is called and the electronic beacon fails: 0.002%
0.2% (from above) x 1% (probability that the electronic beacon fails when activated) = 0.002%. I assume that the probability of being found when you have a PLB is 100%, and when you have the MRG is 99.999%. Essentially, if you have either of the two electronic beacons, you will be found. Therefore the probability of 0.002% approximates the probability that you will not be found because you are in a boat seperation incident, SAR has been called, but your beacon has failed. In this situation, you will also be thinking, "I can see you searching for me, but you can't see me."

If you have both the PLB and the MRG, this probability diminishes to 0.00002% because of the redundancy factor when you have two electronic beacons.

I may have inaccuracies and errors in the above calculations, but this does not really matter. They are ball park estimates to help me think about the situation. To me, the estimates tell me that every diver should get at least one of the two electronic beacons. If you dive remote third world locations where SAR may not get to you within 24 hours, then having both a PLB and MRG may be desirable because they have different characteristics that are highly complementary in such a situation.

Good thinking excercise. You are probably more prepared than most ocean divers.

 

[Dan]

When do you plan to use your dye? In the initial phase within 30 minutes of surfacing, or ary you saving your dye till after SAR is called?

What @tursiops says.

When I hear & see an airplane coming towards me, that is when I spread the dye to help them spot me floating on the vast sea. I may not use it during the night. That’s when I deploy the twirling glow stick & strapping the strobe on top of the DSMB.

Hopefully I’d never use it. There is too much pollution in the sea already. I don’t want to add it if I don’t have to.

 

[Dan]

The more I learn about the MRG, the more I like it. The man overboard AIS signal is used by mariners and there are devices designed for mariners that use the AIS platform. See AISLink Personal Man Overboard Beacon | ACR ARTEX To me, this reduces the probability that mariners will ignore the MRGs AIS signal. The MRGs 80 - 90 hour transmission window is highly desirable to me if this is correct. There are AIS products such as the ACR AISLink that claim a more modest 24+ hours. I suspect that the Nautilus claim that, "man overboard distress message will be broadcast to all AIS equipped ships up to 34 miles away" overstates the broadcast range, it will nevertheless be measured in terms of miles and is still significant. Note that the ACR AISLink claims a range of 5 miles. A circle with a radius of 5 miles is enormous.

I believe that satellites can detect ship AIS. See Automatic identification system - Wikipedia This does not mean that they can detect the MRG. However, if the MRG has a horizontal range of 34 miles (or 5 miles) to ships, then its signal will penetrate miles into the heavens where satellites reside.

To me, the differences between a PLB and the MRG suggests that they are highly complementary and I'm happy to have both because I will be diving locations where I do not expect SAR to show up within the transmission window of my PLB (roughly 24 hours).

That’s another reason I didn’t get the old Nautilus Lifeline with radio. This huge device doesn’t send out alert to AIS.

As @tursiops mentioned in this thread Nautilus Lifeline Radio (on page 14, post # 140) that during the alert transmission, AIS system of the boat will display the MRG’s MMSI. The first 3 digit of the MRG’s MMSI, 972, signifies Man Over Board. The last 4 digit, 6005, signifies the last 4 numbers of S/N of my MRG.

I’d give the LOB’s captain my MRG’s MMSI prior to go on a diving trip with the LOB. Later on during one of those high voltage current dive, I get blown away and don’t see any skiff at the surface, I could just launch the MRG’s SOS. The boat AIS would receive an SOS from MMSI 972-69-6005. The captain will know that there is a Man-Over-Board (972) and that person is me (6005).

 

[MargaritaMike]

@Dan_T

I'm curious. Do you have a dollar figure for the cost of your "Save A Lost Diver" kit? Texas currency is ok.

Cheers -

 

[Dan]

@Dan_T

I'm curious. Do you have a dollar figure for the cost of your "Save A Lost Diver" kit? Texas currency is ok.

Cheers -

I just made a quick look up at Amazon.com & get the following price:
Safety Kit
1. 6’ DSMB with 100’ line in spool - $73
2. Dive Alert - $80
3. Signal Mirror- $10
4. Nautilus Marine Rescue GPS - $190
5. PLB1 - $245
6. Dive light - $15
7. Strobe - $50
8. Glow stick with 6’ string - $12
9. Leash with carabiners - $30
10. Dye Marker - $20
Total to about - $725.

You could save money by shopping around for less. Some include free shipping with my Amazon Prime. I got the PLB1 with $50 rebate. The item 9 (leash with carabiners) can be replaced with reef hook for less cost ($15)

 

[CWK]

I don’t expect myself to be found alive after 3 days lost at sea. So, I don’t plan to carry safety gear, that I’d hopefully never use (knock on wood), excessively. Streamlining vs Christmas tree.

I guess Spare batteries in a pocket counts as streamlining, but exactly when do you plan to do your almost dry battery change if the MRG can transmit for 80 to 90 hours?

 

[Dan]

I guess Spare batteries in a pocket counts as streamlining, but exactly when do you plan to do your almost dry battery change if the MRG can transmit for 80 to 90 hours?

The 2 CR123 Lithium batteries are small, cost about $3 and take hardly any space in the waterproof pouch. Since they are easily replaceable, why not? You just never know how long the ones in MRG would last after a few tests. It’s a cheap insurance / backup on the battery life.

Isn’t it a good practice to carry spare batteries in a long (1-2 week) dive trip vacation anyway? I usually carry spare dive computer & camera batteries. So carrying spare batteries for the MRG should be any different than the other electronic devices.

What if I got blown away in the 2nd day of a 10-day LOB dive trip, launched my MRG alert, then the boat found me after a hour or two tracking the MRG GPS location using their AIS system. At least it’s good to have spare batteries to replace partially used batteries for the rest of the trip. I can swap the batteries while I’m back in the boat and keep the partially used ones as backup batteries until the trip is completed. Then swap the partially used batteries with new ones when I’m back home.

 

[CWK]

I originally carried a 500mL water bottle & foldable snorkel in BCD pocket. I had to remove & replace them with MRG, Dye Marker, glow stick, leash & strobe. I figured that I could survive floating at sea for a day without water & snorkel.

There are places where snorkelling with mantas, whales, or whale sharks is permitted but not scuba so I like to have a snorkle with me. In some circumstances you may need to do a long surface swim to shore. This would be easier with a snorkel. Check out: Where the hell did our boat go?

 

[CWK]

Good thinking excercise. You are probably more prepared than most ocean divers.

I started diving again in April 2017 after a lapse of some 20 years. In May 2017 I went to dive Sipadan and buddied with a visiting Padi Instructor for about 4 days. He had some equipment attached to his BC that one normally does not see. I recognised them to be a pony and a strobe. We talked some and he told me that he had experienced boat seperation in Bali as the result of being caught in a washing machine. I geathered that he was contemplating life whilst drifting in the sea for several hours. He showed me this funny gadget called the Nautilus Marine Rescue GPS that he had in his BC pocket. I figured that as I was going to be diving Bali and other places that he was diving, I could do worse than getting the MRG, so I bought one on Amazon in June 2017.

Later, I found this board and discovered that the consensus was that the MRG was inferior to a PLB primarily because many marine vessels in the third world, such as fishing boats, do not have marine radio. So I bought my PLB in August 2017.

I became more prepared than most because I kept meeting divers who had experienced boat seperation - 4 in the last 12 months.