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-   -   EPIRB's (http://www.sailnet.com/forums/general-discussion-sailing-related/42047-epirbs.html)

Jaxxon 04-07-2008 04:55 PM

EPIRB's
 
I have a question for some of you salts out there. A couple of years ago I crewed on a sailboat from the Canaries to Barbados. Besides myself, there were three other crewmen, the Captain (an Aussie) and his wife. We were about half way across and were all in the cockpit late one afternoon and the discussion of EPIRB's came up. The Captain said he had one, but that if anything dire happened to us this far out, even if we set it off, it was unlikely that anybody would respond. He claims that these things are mainly for coastal cruising, and that nobody would even respond to a signal that far out in the ocean. I argued that there might be a ship just beyond the horizon, and that they could dispatch that ship to come check it out. He said that was possible, but a pretty remote chance.
Anyway, he say's they're useless in the middle of the ocean. Anybody know anything about this for sure?

sailingdog 04-07-2008 05:56 PM

The captain is full of it IMHO... the EPIRBs are useful anywhere you might be sailing. While the response is far more likely to be fairly timely when you're coastal cruising, since you're closer to the responders.

The EPIRBs report to satellites, not coastal ground stations, so are useful, even in the middle of the ocean. Several rescues in the last few years were due to timely use of 406 MHz EPIRB.

Be aware that the older EPIRBs, not the 406 MHz ones, are no longer legal for use.

Idiens 04-07-2008 06:00 PM

Maybe he had a very old EPIRB that only worked on VHF 121.5 MHz. Most of the new ones (probably all) transmit on both 406 MHz and VHF. The 406 is picked up by the COSPAS-SARSAT satellites and relayed to the rescue services. The satellites can locate the EPIRB to a nautical mile or so, anywhere on the globe. The posh EPIRBS carry GPS receivers and transmit their position in the 406 message, so that makes location much better. The 121.5 is used by civil transport aircraft, who will report the position they heard the EPIRB and it is also used by rescue services when closing in to direction-find the EPIRB at short range.

So you friend is partly wrong, even if he only had a 121.5 MHz EPIRB, passing civil aircraft would hear and report its transmissions in mid ocean. - If they were passing.

sailingdog 04-07-2008 06:12 PM

Idiens-

IIRC, the new ones broadcast on 406 MHz, and 121.5 MHz. The 406 MHz is for satellite information transmission. The 121.5 MHz is for SAR RDF purposes. The older EPIRBs could be detected by satellite, but did not give as much information as the newer 406 MHz ones do.

From the DHS website on EPIRBs:

Quote:

Types of EPIRBs

Emergency position indicating radiobeacons (EPIRBs), devices which cost from $200 to about $1500, are designed to save your life if you get into trouble by alerting rescue authorities and indicating your location. EPIRB types are described below:

Class A
121.5/243 MHZ. Float-free, automatically-activating, detectable by aircraft and satellite. Coverage is limited. An alert from this device to a rescue coordination center may be delayed 4 - 6 or more hours. These devices have been phased out by the FCC and are no longer recognized.

Class B
121.5/243 MHZ. Manually activated version of Class A. These devices have been phased out by the FCC and are no longer recognized.

Class C
VHF ch15/16. Manually activated, operates on maritime channels only. Not detectable by satellite. These devices have been phased out by the FCC and are no longer recognized.

Class S
121.5/243 MHZ. Similar to Class B, except it floats, or is an integral part of a survival craft. These devices have been phased out by the FCC and are no longer recognized.


Category I
406/121.5 MHZ. Float-free, automatically activated EPIRB. Detectable by satellite anywhere in the world. Recognized by GMDSS.

Category II
406/121.5 MHZ. Similar to Category I, except is manually activated. Some models are also water activated.

Inmarsat E
1646 MHZ. Float-free, automatically activated EPIRB. Detectable by Inmarsat geostationary satellite. Recognized by GMDSS. Currently not sold in the U.S.; however, the Federal Communications Commission is considering recognizing these devices. This service will end 12/31/2006.

Idiens 04-07-2008 06:14 PM

SD- Yes, I was trying to say just that, obviously badly :)

However, I think the 406 MHz signal is still used the same way by the satellites, the more recent change is the addition of GPS and adding its information to the 406 message. The satellites relay the message but still provide their own position measurement on the EPIRB, I believe based on Doppler.

The INMARSAT ones have been discontinued recently (not enough sold) and replaced by the 406 MHz versions. That leaves Cat I and Cat 2 devices on sale.

rennisaint 04-07-2008 08:29 PM

Can't remember the name of the, but there was a book about a guy who managed to (mostly) sink his catamaran in the middle of the Pacific. When his EPIRB went off ships were diverted immediately and aircraft sent to flyover with supplies etc.. He lost his crew (a cat) but made it out alright himself. Now my guess is he would have been fish food if not for his EPIRB. But, if you've read the book he did try his damnedest to kill himself repeatedly by leaving his fricking boat. Anybody know the name of the book?

Plumper 04-07-2008 09:02 PM

It can't hurt to have one, that's for sure.

Classic30 04-08-2008 02:32 AM

The old EPIRBs are not even available for sale over here any more - you can only get the 406MHz ones.

The 406MHz EPIRBs still use Doppler but, unlike the older ones, contain a unique code that identifies the type and name of the ship or person it is registered to so the SAR people know what they are searching for. AFAIK, they are not linked into the GPS system, although some of the more expensive ones can transmit a GPS position.

Another rescue gadget that can get people confused is a SART which looks exactly like an EPIRB, but is designed to show up on a passing ship/aircraft radar as a very hard to miss distress signal and give them a precise bearing to your location.

artbyjody 04-08-2008 03:26 AM

I have a EPIRB and I have two of the personal devices...

Personally, it doesn't matter whether you are only sailing 500 feet outside your marina or sailing around the world...You take your cell phone with you even tho the odds of you having coverage may be slim to none. Nope you take it "JUST in CASE"...

One can argue safety at sea is mainly a result of experience or luck of the draw. But if you have ever been in a experience where your luck was drained out.. You can not argue about not having one... As Properly installed - its one item that when it all goes downhill - that COULD save your life... there are no guarantees (it may not work or maybe no one picks up the distress), but wouldn't you want to be stranded in your car with at least a cell phone knowing it MAY help you? The same goes with EPIRBs and other MOB devices...increase the odds..

Seems the prudent thing to do and one safety item that should actually be mandated in my opinion...After all flares are mandated - they only work if someone is around to see them...one has much better chances with a digital signal announcing the situation than one does when in the middle of nowhere shooting off flares, hoping someone see it...

Its expensive and that is the only prohibitive argument I see against it - but we spend more for less most of the time in our lives and decisions on purchases...IE: Having full sized spares for our vehicles in the event a tire goes flat - what are the odds that you need a full sized spare - not great but lots of us buy them for the peace of mind...

:)

sailingdog 04-08-2008 08:11 AM

Hartley-

Most 406 MHz EPIRBs work as SAR transponders, as they also broadcast on the 121.5 MHz frequency that the SAR craft will be looking at.


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