NavList:

In another thread, I found that the EPIRB / PLB message that is transmitted to the satellites is only to WHOLE MINUTES.  Fractional minutes (tenths) are not transmitted. I stand ready to be corrected on this point, but the data is fairly clear.  I was surprised by this, as the search area is now a one arc minute by one arc minute box.  That may be okay if you are in a big orange lifeboat, but a head bobbing in the water will be much tougher to see.

The purpose of the 406MHz message is to "alert" SAR.  This will put air search over your location.  If your EPIRB/PLB has the 120MHz homing signal, this should help SAR in the "locate" phase.  There are other means to assist in "locate"(flares, smoke, etc).  The "find" phase will always take mark one eyeballs.  Alert, locate, find.  Each phase of your strategy should be considered.

A small, waterproof, handheld VHF radio should be a part of your go bag.  A Digital Selective Calling (DSC) Distress message also transmits your position, but again, only to WHOLE MINUTES.  Fractional minutes are not transmitted.

It seems obvious that when speaking with SAR, that this is your only chance to narrow a search area by a factor of 100!  That is, instead of one by one arc minutes, it is now 0.1 × 0.1 arc minutes, provided you tell them and they can utilize that data.

I am waiting patiently for James Campbell, an instructor at the National SAR School, to provide us some data points.  He spoke up in that other thread.  I can only hope that he does so again, or some other authoritative source will contribute.  

Brad

PS Yes, I do have an EPIRB/PLB.  It is a link in my strategy.  I agree that if you want to be found, it is an excellent tool.  Reliance on a single device, with a single point of failure, may not be the wisest strategy.