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Old 14-09-2011, 07:44   #1
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What Receives 121.5 MHz ?

A new safety device says it broadcasts on the EPIRB frequency and 121.5 Mhz. Is that VHF? I'm looking for something that leads the boat back to the person overboard since we sail as a two person crew and a person could be overboard for a couple of hours before the off-watch noticed.
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Old 14-09-2011, 08:03   #2
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Re: What receives 121.5 Mhz?

I might be wrong--but I think that this is a distress frequency picked up by aircraft (older epirbs) I also think that this frequency will eventually be completely replaced by the frequency that can receive data (coordinates etc.). I like the idea of being able to track a personal beacon from the mothership for a situation like you mentioned. I have not looked into this yet though.
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Old 14-09-2011, 08:08   #3
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Re: What receives 121.5 Mhz?

Hannah, that's the "old" version. You want to go with a 406 MHz unit. Some more info here...NOAA - Search and Rescue Satellite Aided Tracking - Emergency Beacons
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Old 14-09-2011, 09:00   #4
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Re: What receives 121.5 Mhz?

Hannah,

It really IS confusing these days! There is a profusion of new "personal locator" devices and other small communicators designed for both land and water use.

Here's the scoop.

1. Yes, 121.5 mHz is VHF and, along with 243mHz, is an aircraft emergency locator frequency. It WAS the standard for EPIRBs as well, but has almost entirely been replaced by the 409mHz emergency frequency. All new EPIRBs operate on 409mHz. Many or all also broadcast a low-power signal on 121.5 mHz in order to help with direction-finding for close-in location. However -- and this is critical -- I confirmed with the head of USCG's SAR team recently that SAR aircraft mostly DO NOT listen on 121.5 any longer, especially since they are fitted with 409 mHz direction-finding equipment which they have found to be very accurate.

2. In order to make use of the 121.5 frequency, you'd need a special direction-finding receiver and directional antenna. Your regular boat VHF won't do the trick.

3. The 409 mHz signal is MUCH more useful since it allows for faster notification to SAR authorities and, if the EPIRB is equipped with a GPS, it can provide precise location data to SAR teams.

4. 121.5 EPIRBs have been "banned", that is, the satellites no longer listen for them. I'm not sure whether or not commercial aircraft still listen on 121.5.

Bottom line: be sure you have a 409 EPIRB, especially one with GPS. If you're worried about locating a crew overboard, you might think about a personal locator device for the on-watch person and even a waterproof VHF handheld w/built-in GPS (like the Standard Horizon HX-851). It floats, gives you a GPS position, and allows voice transmission on all the marine VHF channels. It also has DSC capability (you can plug in your MMSI number) for distress situations. I have one, and it lives with the on-watch person, attached to his/her inflatable life vest.

A final note: the USCG SAR head -- who is himself a very experienced SAR aviator -- said that one of the most valuable locating devices for night time use is a light. Any kind of light, even a cigarette lighter. SAR pilots these days wear night vision goggles and can see even a tiny light from many miles away. Many locator devices, EPIRBs, etc., have built-in strobe lights -- these are VERY valuable.

Bill
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Old 14-09-2011, 09:00   #5
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Re: What receives 121.5 Mhz?

121.5 is VHF. It is still being used as a homing frequency when inside VHF range. It is no longer being used as a satellite frequency.

If you have sailed on for a couple of hours, you may very well be out of VHF range for someone in the water with a low-power transmitter.
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Old 14-09-2011, 09:22   #6
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Re: What receives 121.5 Mhz?

Hi Hannah,
If you have an AIS receiver onboard, you can get these personnel AIS locator beacons.
We use them on the ship for the crew working the back deck in bad weather when the visibility is really bad.
If some one goes over the side with one of these, they need to be in a position where thet can activate it, ours have a pull cord to activate.
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Old 14-09-2011, 09:24   #7
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Re: What receives 121.5 Mhz?

If you're sailing in the PNW and someone goes over the side, I hope you find out about it sooner than a couple of hours later!!
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Old 14-09-2011, 09:27   #8
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Re: What receives 121.5 Mhz?

the device I'm lookign at is the McMurdo fast find, which has the 406 EPIRB frequency but, I can't for the life of me see how it is going to help me find the captain when he's overboard if my boats VHF won't receive his signal. Maybe I'm missing something.

Last summer I got excited about an personal AIS beacon but then it vanished from the market as far as I could tell. I would welcome any suggestions on how to solve this dilemma.
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Old 14-09-2011, 09:35   #9
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Re: What receives 121.5 Mhz?

The short answer : All aircraft.

Most of us listen out on 121.5 when oceanic or over remote areas and will advise whichever ground station we are speaking with when we first hear an EPIRB transmitting and again when we stop hearing it. Knowing the aircraft's position and altitude and if there are a few other aircraft who can provide similar reports, the ground stations will use this information to triangulate an approximate position of that EPIRB.

Additionally, in some parts of the world, 121.5 is called the guard frequency which every aircraft listens out on, on their 2nd VHF. In this instance, it is very loosely the "equivalent" of our Channel 16.
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Old 14-09-2011, 09:37   #10
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Re: What receives 121.5 Mhz?

We won't launch a helicopter or other SAR asset for a 121.5 signal anymore, but if we are actively flying on a case most of us do monitor that frequency for any signals. We have the ability to turn it off in the helicopter, listen to it, or simply have an visual "Check 121.5" alert on our computer screen while flying. 121.5 should not be your primary way of alerting the world to your distress. If you have a device that transmits on 121.5 though, do not discard it. If you are in an emergency situation you can still activate the device and know the people looking for you will use the beacon to assist their search.

I carry a 121.5 beacon with me every time I fly or boat. I also have an EPIRB on my boat (and the helicopter as well of course) but I'd hate to think I had one less method of being found because I deemed it old technology and left it home.

Btrayfors is right though, a normal VHF won't do the trick for you- you'd need to find a direction-finding (DF) radio. A strobe light at night or orange smoke during the day would be a more fitting solution for your application. Also, consider purchasing a couple waterproof handheld VHFs to attach to your belt/lifejacket/etc. While it can be hard for a boat to find a person in the water, it can be far easier for a person in the water to find a boat. 2 way communications allows the person in the water to direct a boat towards them with "Turn left/right, stop turn" type directions.
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Old 14-09-2011, 09:40   #11
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Re: What receives 121.5 Mhz?

121.5MHz was until recently used as a distress signal via the satellite system but has now been discontinued. Satellite processing of 121.5 MHz emissions ceased on 1 February 2009.
121.5 Phase-Out

Very high frequency (VHF) is the radio frequency range from 30 MHz to 300 MHz.
121.5 MHz falls within the Aircraft band.
The Marine Radio VHF band is between 156158 MHz, with the Maritime Emergency Frequency at 156.8 MHz (Chanel 16).
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Old 14-09-2011, 09:48   #12
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Re: What receives 121.5 Mhz?

Quote:
Originally Posted by Hannah on 'Rita T' View Post
Last summer I got excited about an personal AIS beacon but then it vanished from the market as far as I could tell. I would welcome any suggestions on how to solve this dilemma.

Something like this
Seamark Nunn Limited AIS Beacons
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Old 14-09-2011, 10:22   #13
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Re: What Receives 121.5 Mhz ?

Was looking at the OP's original device, saw this:

Personal AIS

Edit: Sorry, followed your link and see it is the same device from a different vendor. Seems like a good idea, sorry to hear they have disappeared.
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Old 14-09-2011, 10:27   #14
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Re: What Receives 121.5 Mhz ?

To the OP's question, seems like you are looking at the Fast Find 200/201? This from their website:

Quote:
Like the 210 model, Fast Find 200 transmits two signals simultaneously, one to the subscription free global 406 MHz satellite system, and the other (121.5MHz) is a homing signal which will speed up the local recovery response process. Once activated, FAST FIND's signals will continue to transmit for at least 24 hours, at a powerful 5 watt output, the 406 MHz transmission ensures that a call for help gets through whatever the conditions.

FAST FIND also includes a unique SOS LED flash light facility which is manually activated to further assist in speeding up the users recovery during night time rescues.

FAST FIND will operate in temperatures down to -20c and its integral battery has a user storage life of 5 years, so there’s no need for constant battery changes and re-charging.
So, this is essentially like almost all middle-aged EPIRBS, it transmits to the satellites on 406 and transmits to SAR crews on 121.5 for homing. Unless you also purchase a 121.5 direction finding radio for the boat it won't do you much good in the MOB case. Your MOB will be able to tell the rest of the world where he/she is (using the 406 feature), but won't be able to tell you.

Seems like what you are talking about is something like this:

MOB VHF DSC locator

Have no idea on the cost, haven't looked at them myself.

Quote:
The Crewsafe V100 is a water-activated Maritime Survivor Locating Device (MSLD) that transmits accurate and regular GPS coordinates of a man overboard directly to rescuers via VHF marine radio.

This palm sized radio distress beacon can be integrated with a lifejacket or Personal Flotation Device (PFD), clipped to webbing or harness, or carried in a pocket and secured with a lanyard.

When its water sensors detect the wearer has gone overboard, the Crewsafe V100 automatically transmits a “Mayday, man overboard” distress alert using VHF DSC (Digital Selective Calling) [channel 70]. It can also be manually activated.

It quickly acquires a GPS lock, then transmits its GPS coordinates to all vessels in the vicinity, including the parent vessel, and to any onshore VHF receivers in range.

The distress alert is also broadcast on the VHF marine radio emergency channel 16 in a synthesized voice* to maximise the number of people who can receive the alert and respond to the emergency. Alerting range is VHF line-of-sight: 2 to 10NM surface-to-surface and up to 40NM surface-to-air.
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Old 14-09-2011, 11:21   #15
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Re: What Receives 121.5 Mhz ?

There are several MOB devices, Raymarine does one, ACR does one.

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