Re: [Paddlewise] VHF

In a message dated 12/2/98 11:57:09 AM Eastern Standard Time,
sullivaned_at_pop.mts.kpnw.org writes:

<< 
 For Mr. Martin: How does an EPIRB compare in size and weight? Can it run
 on AA batteries (I try to standardize all battery appliances for
 swappage in emergency).

   <snip>

 Somebody else said: "EPIRB require much longer response times (24-36
 hours ?)" ???? Why so long? I really prefer same-day service when I am
 bobbing.
  >>

There are a lot of variants out there, but the manually activated kind of
EPIRB that we'd use --- unless you want to wait for your kayak to sink fifteen
feet before the beacon activates --- are similar in size to a typical VHF
radio.  Maybe a tad bigger.  Some have float collars, which increase the size,
and some have strobes built in which also raise the volume a little.  I'm not
aware of any that use AA batts; by specification, they all use high shelf life
(ten year) batteries --- mostly lithium --- that have to be replaced every
five to six years, depending on the specs of the battery and the system.  You
won't be using these things, running down the battery.  In the best of all
worlds, you'll never use it.  

As to the time delay, yes, the older 121.5 MHz units could be activated where
they would have to wait for a satellite to be in a position to hear them ---
unless, as was noted in another post, an aircraft overhead picked up the
signal, a definite possibility, but not an alternative for which the system is
designed; most likely, the signal will be first picked up by a satellite in a
remote location.  That time delay is up to two hours. From there, there are
potential delays in cross referencing the system and delays in a launch of SAR
services; 24-36 hours sounds extraordinariy high to me --- I was in the
business for many years --- but I suppose it's possible.

With the 406 systems, the alert time is instantaneous --- vice up to two hours
--- and the identification of the vessel is immediate.  Typically, cognizant
SAR authorities will receive notification in near real time and can make phone
calls in an attempt to confirm that the vessel is, in fact, underway and could
logically be in the area in which the COSPAS/SARSAT equipment says it is.  At
that point, SAR services are activated.  And if GPS data was incorporated, SAR
should be able to get an updated "fly-to" position within minutes.  No
guarantees, but the capability is designed into the system.

Jack Martin
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