Paul Hayward wrote: <<It seems to me (with no vestige of authority ;-), that EPIRBs and PLBs must be expected - by their makers and by their certifying authorities - to be intended to be used very, very near to the surface of the sea.>> Haven't followed this thread carefully, so apologies if I'm repeating info from earlier posts, but, from Navy experience and a little professional technical knowledge, I can stipulate that Paul's spot on in his analysis. Having been in the combat search and rescue business for the U.S. Navy for a while -- if a while back -- and in the distress beacon business, I can confirm that personal locator beacons, generally, are designed to be operated effectively by a swimmer, occasionally submerged while in operation, and remain functional for the majority of the time. We have radio beacons installed in floating modules in Navy inventory that are designed to deploy from aircraft in crash scenarios and to broadcast distress messages; these modules are equipped with fixed antennas in their skin. Higher and drier is better, but in water and occasionally awash still works. Satellite reception and fixation is more problemmatic, but the systems still work, and would work better in Paul's scenario -- held high on a personal flotation device strap. (Many transmitters have spring-like antennas that deploy to an upright position when the system is activated, increasing the signal strength and minimizing attenuation caused by overwash.) To Paul's point, it's also likely that a swimmer in Aukland would have better GPS reception and distress signal transmission than a swimmer in a fjord off the South Island, and the South Islander would have better GPS reception and distress signal transmission than would a swimmer in McMurdo Sound because of lattitudinal limitations and satellite exposure. Offsetting this, the deterioration in signal strength in these scenarios would be more than offset by deterioration in the swimmer's environmental scenario and exposure, thus decreasing the amount of time each swimmer would have to worry about declining signal strength. Joq Martin *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Mon Nov 09 2009 - 08:30:26 PST
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