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

[Dan]

Looks like if you had a Halcyon bpw, and matching MC storage pac attached to the backplate, this raft can fit neatly in there.

BC Storage Pak

PERSONAL LIFEBOAT
Modeled after the Air Force and Navy Single Man Life Boat, the DLR provides unprecedented safety at sea. The DLR can be integrated into the MC system, hidden neatly behind the diver's back in the MC Storage Pak, or folded into an optional external pouch. Spend the night, salvage rainwater, and broaden the "visibility dot" on the sea literally ten-fold with this six-foot, 300+ pound inflatable boat. The device can be inflated orally or with your BC hose.

I do suppose they mean 300+ pounds of lift and not that it weighs 300+ pounds!

Honestly I think it’s a discontinued product as I couldn’t find it on the Halcyon website.

Yep, unfortunately I don’t have Halcyon bpw. I just have Cressi TravelLight BCD. I try to carry 1 < 50lbs divebag and carryon backpack for my camera. That’s it. So, I need to be choosy on what safety kit I’d carry & not going to remote <60F (15C) water.

 

[CWK]

My thought is time is of the essence. The sooner I get rescued, the better my chance to be found alive.

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.

 

[CWK]

I don’t do probability estimates.

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.

 

[CWK]

I plan to turn on my MRG right after the boat fails to see my DSMB (within 30 minutes of surfacing). Will keep it ON at all time. Don’t want any boat to miss my alert signal.

Once no boat is seen in the horizon, ...

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?

 

[tursiops]

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?

You use the dye when you see an airplane. It serves no purpose otherwise.

 

[CWK]

Once no boat is seen in the horizon, then I’ll launch my PLB1. Having 1 watt VHF (30-300 MHz) for surface-surface SOS transmission by MRG & 5 watt 406 MHz surface-satellite SOS transmission by PLB1 for the first 24 hour will greatly increased my chances to be found alive.

After the PLB1 is dead, I’d still have the MRG to emit the VHF signal. Once it runs out of battery, then, I’ll replace the batteries with fresh ones. My BCD will be fully inflated to keep my head, chest & arms above water to do “dry-enough” battery change procedure above water surface.

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).

 

[Jay]

I don’t do probability estimates. My thought is time is of the essence. The sooner I get rescued, the better my chance to be found alive.

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.

Not really because from the lost person's perspective they will never know it's now a recovery and not a rescue. Even pre-death in the hospital they were rescued.

I have this 'funny' image of you saying 'how now brown cow' to aid the rescue!!!!

 

[CWK]

You use the dye when you see an airplane. It serves no purpose otherwise.

The alternative view that it will be of assistance for boat rescue has been expressd by Jay_Antipodean. Quoting from earlier in this thread:

I think it would be very handy if there are swells ... beautiful coloured wave crests (for how long I don't know).

 

[tursiops]

The alternative view that it will be of assistance for boat rescue has been expressd by Jay_Antipodean. Quoting from earlier in this thread:

The dye spreads out normal to the wave crests, not along them.

 

[CWK]

The dye spreads out normal to the wave crests, not along them.

OK. Got that. FWIW, I expressed the view that dye would only be useful for air.

I was interested to find out when the OP would deploy his dye. He may have a different POV.