A pop-up float recovery system for coastal oceanographic tripods

Abstract

The recovery package described here was used as the primary retrieval system to recover tripod instrument platforms from a depth of 90 meters. The device uses dual in-line burn wires, one of which is acoustically commanded from the surface ship. The other is set to release by back-up timer, ensuring recovery in the event of a poor acoustic command channel. The burn wire activates spring loaded cam latches which release the float package and pull a ~ inch Dacron line to the surface. The float package is recovered and the line is used to winch the tripod to the surface for recovery by the ship's crane. Major benefits of the system are reliability, low cost, light weight, and use of many off-the-shelf components. The float package provides 50 pounds of buoyancy and is fabricated using commercial fish trawl net floats. The retrieval line container is separate from the float assembly, and is fabricated from plastic storage containers. The line is coiled and restricted to prevent unpackaging due to waves or current action. The system described here is not appropriate in areas of high current or great depth due to drag and dead weight of the lift line.