Figure F12. Diagram of a borehole instrument string deployed in Hole 1253A (4376 meters below sea level). The string is –206 lb when released from the ship. At the seafloor the drop weight (see SINKER in CORK in “Supplementary material”) is removed, and the string is –56 lb. If the string needs to be heavier, floats can be removed from the top of the string. Once the string is safely placed in the wellhead, the floats are released and the string descends. This example lacks a transponder and directional transponder (homing device) on the drop weight. These instruments add more weight to the system, help locate the string on the seafloor, and are recovered once the string is located. In later deployments the lead wire is replaced with a middle sinker bar (–50 lb in seawater), requiring an additional float.
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