Circular search

An underwater circular search is a search and rescue strategy conducted by a diver swimming around a fixed pivot point. In some cases a second diver can anchor himself to the bottom and act as both the pivot point and line tender. The diver and line tender communicate with each other using line pull signals. When the diver has completed a full revolution of the search, the tender signals the diver and advances another section of line so the search can be expanded further from the pivot point.

Communication
Most public safety divers and many recreational divers 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

Safety
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 arch shaped pattern as opposed to full circles. This is especially important when visibility is poor.

The last consideration is that the diver is responsible for maintaining tension on the search line so the signals can be transmitted and received. An illustration of this pattern and directions can be downloaded from the webpage maintained by the International Association of Dive Rescue Specialists (IADRS). Visit International Association of Dive Rescue Specialists and check the "download" section for a PDF with illustrations.