Personal Emergency GPS Beacon

[mjcoyne]

To be honest I thought I had just dreamed of these, its a good think to know that they actually do exist. I have not made a trip down to any tropical locations for a week of diving yet but I might just look into one of these when I eventually do - too many stories of lost divers on Caribbean dive boats if you ask me....

[MConnelly2]

This is a subject I know a bit about - as does Navy OnStar, my fling-wing, flying squid (all in good fun), counterpart, who I'm sure has good info to share.

Alrighty, all new EPIRBS transmit primarily on 406.025MHz. They transmit what we call a "hex code" to the COSPAS-SARSAT satellite constellation, which includes both GEOS (geostationary) and LEOS (Low Earth Orbiting Satellites) - in other words, satellites for the express purpose of resolving EPIRB positions, and packages onboard weather satellites for picking up 'first alerts' and initial positioning. This hex code is the unique identifier for that beacon - the device transmits it to the satellite, first chance the satellite gets to transmit it to a ground station, it does, from there to MCC in Suitland, Maryland (still, I think?), and then to the appropriate RCC (Rescue Coordination Center). RCC will enter the number into the NOAA database, and if the beacon is registered, they'll have the names, contacts, vessel name (if applicable), homeports, all kinds of information. If the beacon isn't registered - let's not go there. We're all smart enough here to register our beacons.

So, RCC gets this info, and either a preliminary or resolved position, passes it along to the appropriate SAR Mission Coordinator, SMC launches an appropriate SRU, whether it's a Motor Lifeboat (like mine) or a helicopter (like Navy OnStar).

Now, these beacons ALSO transmit a low powered signal on 121.5MHz. This is really, really cool, because once we get close to our commence search point, or to our datum (the most probable location of a search object corrected for movement over time), we can use a radio direction finder on that 121.5 hit, and run right down the bearing. If we keep that bearing steady, as soon as it flips, the helo would look down, and I'd stop because I just ran over my search object. (kidding)

Now, until recently, there were two types on the market - the older Class B jobbers, those that transmit solely on 121.5, and the newer 406's. 121.5's aren't legal anymore, as of a year or two ago, and the false alarm rate is so unbelievable, it's all about the 406's now. There are also some units with either an integrated GPS, or an interface for one, which will transmit the Lat and Long with the first alert. That's kind of cool, too, but if you consider the working time for COSPAS-SARSAT to resolve a 'standard' 406 hit vs. the alerting, processing, launch, and en-route time of the response - well, it's a feature worth considering before making the additional investment. We each have different measures we want to take with our equipment.

Best piece of safety gear for coastal floating around and waiting for the boat or flingwing? A strobe. Strobes are really really cool and make people really (relatively) easy to find. Not that I mind a challenge, but, really, who wants to be that challenging search object?

[chinacat46]

I've dove a few liveaboards that provided EPIRBs. One in Palau and the other in the Galapagos. Both have some extreme drift diving. In Palau they gave you one per buddy pair. Not to good if your buddy has it and you get seperated.

[Navy OnStar]

Originally Posted by MConnelly2

This is a subject I know a bit about - as does Navy OnStar, my fling-wing, flying squid (all in good fun), counterpart, who I'm sure has good info to share.

Now, these beacons ALSO transmit a low powered signal on 121.5MHz. This is really, really cool, because once we get close to our commence search point, or to our datum (the most probable location of a search object corrected for movement over time), we can use a radio direction finder on that 121.5 hit, and run right down the bearing. If we keep that bearing steady, as soon as it flips, the helo would look down, and I'd stop because I just ran over my search object. (kidding)

Best piece of safety gear for coastal floating around and waiting for the boat or flingwing? A strobe. Strobes are really really cool and make people really (relatively) easy to find. Not that I mind a challenge, but, really, who wants to be that challenging search object?

MConnelly2, our resident Puddle Pirate , has posted some great info. Here's the things I would like to add.
First, I like the 121.5 because we can DF (direction Find) down the bearing line as he pointed out. I'm not sure about What freqs the USCG can track, but this is the easiest frequency for us to DF on. (actually any VHF or UHF freq would be easy to DF if we knew you were transmitting on it) But as he pointed out the 121.5 has been phased out. (except the Military as I'm still using a 121.5) So If you had a water proof UHF or VHF radio with you, and you listed that in your dive plan that you left with a responsible adult, that info would be given to me and I could put that frequency into my DF and track right to you.

Second, Strobes or any other light at night....A must. If I am launched at night I will be on NVG's (as will the USCG) and those lights will increase your detection radius at least 10 times. I can pick-up aircraft position lights from 60 miles away on NVGs.

[MConnelly2]

Yup, 121.5 would be what I'd use to DF an EPIRB hit. If I had communications on a VHF, I could plug in any other channel, but with an EPIRB, I can assume a 121.5 transmission.

The biggest problem with the older 121.5 EPIRBS is the notification. It's just a tone, nothing more. With the 406's, we get awesome composite notifications, so we know that that 121.5 that we're looking for is, well, in need of being looked for. Military can get away with it because of the much tighter operational control - if someone splashes, someone knows when and where, usually immediately. Most other boats and aircraft don't operate on comm skeds and the various other 4C arrangements.

Strobes are awesome with night vision, though. Even from the surface in moderate weather, you still see the 'flare' from waaay out. Takes a lot of the art and panache out of it.

[No Misses]

I have a question regarding what is easier to see with NVG, xenon strobe or blue LED? I have a Xenon strobe that lasts for just a couple of hours on 2 AA batteries. The "Glo-Tube" that I just purchased has a burn time of 30-80 hours depending on the flash mode selected. In my unscientific testing, with a naked eye, I believe that the Blue LED is brighter than the strobe. How would they compare when using NVG? is blue one of the amplified light colors or would it be muted?

[highdesert]

I like the idea of Glo-Toob set to strobe mode permanently fixed to an eye at the top of my sausage. It's small enough that it doesn't really affect the size of the rolled sausage. Have to remember to test it on occasion ...

[tonka97]

I just had my EPIRBS mounted on my slung 30 c.f. pony tank. The cannister is good to 300 feet, but was quite pricey as I recall. EPIRB

The TSA inspectors found the cannister intriguing!

A little insurance for future drift diving.

[junzhang]

Originally Posted by tonka97

I just had my EPIRBS mounted on my slung 30 c.f. pony tank. The cannister is good to 300 feet, but was quite pricey as I recall. EPIRB

The TSA inspectors found the cannister intriguing!

A little insurance for future drift diving.

thanks for sharing but they are a bit too huge for me, won't be good for backpacking use though

[tonka97]

Originally Posted by junzhang

thanks for sharing but they are a bit too huge for me, won't be good for backpacking use though

My EPIRB is not huge, and it makes very little change in my configuration. I enjoy cruising slowly and hovering, and hardly know my slung pony and EPIRBS are there.

I take the EPIRB with me on motorcycle journeys too; fits easily in my tank bag.

So many toys, so little time!!