System including a dead weight and equipment on a trolling line released from and retrieved to a receiving structure of a vessel, the dead weight including a controllable element for blocking and unblocking the line, so as to immobilize the line relative to the dead weight in the blocked configuration, and to allow the line to run relative to the dead weight in the unblocked configuration; a first detection element for detecting whether or not or not the equipment has moved to a predefined distance from the dead weight; a control element configured, in case of an order to release: —in a step 2L, to release the equipment from the structure, —in a step 3L, when the first detection element detects the equipment has moved to the predefined distance, to then release the dead weight and control the blocking and unblocking element to shift to the blocked configuration.