EPIRB Search and Rescue Patterns: Part 2
Above: the that-morning patterns run by Coast Guard and Navy aircraft in their search for survivors of a Massachusetts commercial fishing boat whose EPIRB activated offshore in the dead of a New England winter. Note that the Coast Guard's dirft model sent them on a pattern that extends far southeast and east/northeast of where the EPIRB was initially spotted by an overflying Coast Guard jet.
If Coast Guard or other search-and-rescue air and seacraft are in search of us after receiving word, via personal locater beacon, SPOT, VHF radio maday or friend [link forthcoming], that we are lost or in trouble, they'll make many assumptions about where we'll drift as time wears on.
Their predictions come from drift models (formerly JAWS, now SAROPS) that take into account surface current, tide and wind.
Created by tides and winds, surface currents tug us, along with our gear and kayaks, in reasonable-to-assume directions, which gives search-and-rescue personnel a leg-up on where in a vast ocean or bay to concentrate their resources. But we drift differently than a sailboat, which drifts differently from a person in the water, which drifts differently than a sinking fishing vessel, etc.
The Coast Guard takes into account all those differences - which drives home the point of identifying in a mayday what kind of boat we're in.
The Coast Guard factors all of those differences into how they calculate their search model for us or whoever has gone missing.
In the image above , you'll notice that the Coast Guard in New England (US, Boston area) made easterly assumptions about where the crew of Lady Luck, a 55-foot Newburyport, Ma. commercial fishing boat, had drifted in the several hours after the sunken vessel's EPIRB emitted its distress signal.
Were the search for one of us, equipped with a personal locater beacon [link forthcoming] or not, the Coast Guard would assume something similar about our drift.
Since time is of the essence in all rescues, and especially in this case, given that the Lady Luck sank during the winter, the Coast Guard concentrated their densest search patterns where they assumed the crew, in either survival suits or a life raft, would have drifted.
The image below shows the later, that-afternoon search. Note how the drift model has begun making different predictions now that time has worn on and conditions have changed: the densest searches now took place far northeast, and southeast, of where the EPIRB was initially located.
By now a Coast Guard cutter and Canadian helicopter have joined the search. The search patterns take on an even more easterly aspect, as well as north and northeast, of the of the initial sighting of the EPIRB:
Later in the day the search shifited further east, with the densest patterns running north and east, but trending southeast, of the original sighting:
The search would grow ever wider in the coming 36 hours. Neither survivors nor the Lady Luck -- aside from assorted pieces of commercial fishing gear that floated off the sinking boat -- were recovered.
The search pattern evolved further, as you'll note in the third post.
To read more about the personal locater beacons which act as stand-ins for EPIRBs for kayakers in remote waters, and about the newest addition to emergency electronics, the SPOT beacon, which sends text or email messages and Google Maps showing your exact location, to friends or emergency personnel, wait a few days while I post up photos and video I shot of one of the former, available from plbrentals.com
copyright 2007Just Another Guy Named Dave
images courtesy USCG
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