underwaterjackstay search is a search and rescuestrategy conducted by two divers swimmingalong a fixed search line.
There are two techniques for performing a jackstay search.
The first method involves the divers starting at "opposite" ends of the search line, which has been set along the edge of the search area. The two divers swim towards each other, each holding the line in (conventionally) their left hand, thereby each search the area immediately to either side of the line, passing each other at the middle. Once they have each completed the sweep, they then each reset the line on a parallel course, but a few meters further into the search area. They they repeat the sweep, again crossing at the middle, and repeat the pattern until the object of the search is located, or until they cover the entire search area.
The second method involves the divers starting at the "same" end of the search line, which is similarly set along the edge of the search area. The two divers swim together, one on each side of the line, thereby searching the area immediately to either side of the line. Once they have completed the sweep, they then reset that end of the line a few meters further into the search area, so that the line now runs at a slight angle to its original course. They then both sweep back across the line, either searching much of the same ground over again, or simply returning to the start point. Once they reach the start point, they then move the other side of the line a few meters further into the search area so that the line is once again parallel to its original course. They then repeat the pattern until the object of the search is located, or until they cover the entire search area. The second method is longer and slower, and is used more frequently either in extremely limited visibility, where the divers do not wish to lose contact with each other, or where the object sought is particularly small, and they wish run the pattern twice, once from each side, in case the object is masked by a larger object on the sea bed when approach from one side.
Most public safety divers and many
recreationaldivers use the following line signals while conducting searches underwater.
Tender to diver
*One pull on the line: okay, okay?
*Two pulls: stop, take out slack, reverse direction
*Three pulls: come to the surface
*Four pulls: stop, don't move (there could be danger ahead or a boat entering the search area)
Diver to tender
*One pull on the line: okay, okay?
*Two pulls: advance line
*Three pulls: object found
*Four or more pulls: assistance needed
With the exception of the "okay" signal, the pulls are not acknowledged by the recipient. If the proper response is not noticed after a line signal, it is repeated.
It is important to note that divers should be well trained before attempting this type of search. Because of the potential hazard, many public safety dive teams prefer to have the line tender on shore and modify the search to an
archshaped pattern as opposed to full circles. This is especially important when visibility is poor.
* [http://www.ucidiver.com/jackstay.html Underwater Criminal Investigators - Jackstay search]
* [http://www.bsac.org/uploads/documents/Resources/SDC_Notes/srins.pdf British Sub-Aqua Club - Search & Recovery, Instructor Notes]
* PADI Search & Recovery Manual,
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