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AIS and DSC Man Over Board

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    AIS and DSC Man Over Board

    Does anybody have any of the AIS and DSC Man Over Board personal beacons?

    In our area if you go overboard you will be long dead before a satellite based system brings help. A AIS and DSC baserd system will bring immediate help though, since it alerts people in your vicnity.

    KEVIN SANDERS
    4788 LISAS WAY
    SEWARD, ALASKA

    #2
    Kevin,
    i carry a DanBouy which is good if you know about a MOB. For the unknown MOB, ie cruising at night or when crew are resting, have you seen the OLAS system? Pairs to your phone causing it to alarm if a MOB event occurs. Additionally, your phone gives you the bearing to the MOB.

    http://www.ybw.com/expert-advice/ola...ble-time-53348
    Jim Gandee
    1989 3888
    Hino 175's
    Fire Escape
    Fyrflyer@ca.rr.com

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      #3
      I just bought a ACR PLB-375 ResQLink.
      Unfortunately, what I really need is something that can put out a beacon if I were to hit the water unconscious (I spend a lot of time fishing alone)
      97 2859

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        #4
        Originally posted by JThiessen View Post
        Unfortunately, what I really need is something that can put out a beacon if I were to hit the water unconscious (I spend a lot of time fishing alone)
        I doubt you'll find one. GPS signals are very weak and only penetrate a few mm into the water - I think the math goes that only 1% of the signal strength remains after about an inch of penetration into seawater. The fact that GPS works at all is a testament to how sensitive we've been able to make electronics, not how powerful the GPS signals are. So it's be extremely difficult to design any automatic GPS beacon which works reliably if it's attached to an unconscious person. You just can't guarantee a clear GPS signal in that case. And since AIS and DSC rely on GPS for a position fix...

        Strobes and radio beacons would work however. Longer radio wavelengths will penetrate deeper into seawater. GPS is at 1.2 and 1.5 GHz. Marine VHF is around 160 MHz, so the waves are nearly 10x longer than GPS. And the fact that receiving VHF antennas are oriented vertically means you can design an emergency VHF beacon antenna to stick up out of the water. (Because satellites are mostly above us, GPS antennas have to be oriented horizontally for best reception.)

        I know that's not what you wanted to hear, but this is a limitation of physics. It's part of the reason why the self-deploying EPIRBs are so much more expensive than PLBs - the manufacturer has to design a reliable release and floating mechanism which will allow the EPIRB to surface and stay far enough above seawater to get a position fix.

        Edit: Maybe you can strap a handheld VHF radio with DSC to your life vest, and figure out a way to rig a water-activated switch to the DSC transmit button. If it's left on all the time, the radio would pick up your GPS location while you're out of the water, and remember it when you're in the water. Of course if you're unconscious and the radio antenna is underwater, the signal is not going to go very far.
        1994 2556, 350 MAG MPI Horizon, Bravo 2

        Comment


          #5
          Originally posted by JThiessen View Post
          I just bought a ACR PLB-375 ResQLink.
          Unfortunately, what I really need is something that can put out a beacon if I were to hit the water unconscious (I spend a lot of time fishing alone)
          Read the info on the OLAS system . .. . sounds like it might be what you're looking for . . . only you would need to have it alert someone else. Don't know if those capabilities are in there or not but might call and see.
          1998 Avanti 3685 - "Dad's Dream" w 454 Mercs - just a rockin' an'a rollin'
          Former - "Home Aweigh" 2003 - 2452 Bayliner Cierra Classic Hardtop Cruiser
          WQQM835 MMSI: 338147209
          James H. Stradling

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