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Old 25-09-2013, 08:32   #1
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Man Overboard Devices

I bought an old system which has two 121 mhz wearable, water-activated transmitters, and an alarm/directional receiver.

If someone falls overboard, an alarm sounds, and you point the receiver to get the direction to the victim. Old, crude, but the basic functionality is more or less correct.

Theoretically the new AIS SARTs should be a great leap forward, since they give not only direction, but lat-long of the victim. Besides that, they require no special receiver -- any AIS receiver will do.

The only problem is that they are all manually activated. What if the victim is a frightened child, or an unconscious person? Then that's as good as useless.

I actually think VHF DSC might be the better technology for this use. How about a device which:

1. Is wearable, with water activation, and water-activated antenna deployment.

2. Sends a DSC distress message when activated, and repeats it with updated position.

3. Can be interrogated by DSC -- Position Request/Position Report protocol. So even if it doesn't go off automatically, you can interrogate it and get the position of the device -- and this doesn't set off alarms everywhere, either, in case it's not an emergency.


The last function particularly useful in case of children -- you don't know where they are, they may or may not be in trouble, you don't want to set off alarms if there is no emergency, but you really want to be able to see where they are.

What do y'all think? Maybe someone would make such a device?
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Old 25-09-2013, 15:43   #2
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Quote:
Originally Posted by Dockhead View Post
I bought an old system which has two 121 mhz wearable, water-activated transmitters, and an alarm/directional receiver.

If someone falls overboard, an alarm sounds, and you point the receiver to get the direction to the victim. Old, crude, but the basic functionality is more or less correct.

Theoretically the new AIS SARTs should be a great leap forward, since they give not only direction, but lat-long of the victim. Besides that, they require no special receiver -- any AIS receiver will do.

The only problem is that they are all manually activated. What if the victim is a frightened child, or an unconscious person? Then that's as good as useless.

I actually think VHF DSC might be the better technology for this use. How about a device which:

1. Is wearable, with water activation, and water-activated antenna deployment.

2. Sends a DSC distress message when activated, and repeats it with updated position.

3. Can be interrogated by DSC -- Position Request/Position Report protocol. So even if it doesn't go off automatically, you can interrogate it and get the position of the device -- and this doesn't set off alarms everywhere, either, in case it's not an emergency.

The last function particularly useful in case of children -- you don't know where they are, they may or may not be in trouble, you don't want to set off alarms if there is no emergency, but you really want to be able to see where they are.

What do y'all think? Maybe someone would make such a device?
http://www.briartek.com/products-ser...itters/orcadsc

Dave
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Old 25-09-2013, 16:54   #3
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Re: Man Overboard Devices

Quote:
Originally Posted by Dockhead View Post

(...)

Theoretically the new AIS SARTs should be a great leap forward, since they give not only direction, but lat-long of the victim. Besides that, they require no special receiver -- any AIS receiver will do.

(...)

The only problem is that they are all manually activated.

(...)

What if the victim is a frightened child, or an unconscious person? Then that's as good as useless.

(...)

I actually think VHF DSC might be the better technology for this use. How about a device which:
I think older AIS receivers do not show AIS MOBs.

I believe I have seen an auto one too.

I am 100% with you about a DSC device - I thought about this too - more boats have DSC radios than AIS receivers, and all the blocks are out there - we would only need THE device.

Standby.

b.
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