Constant tension hoisting member

A constant tension hoisting system having a single-lever control for a winch having a drive torque variable from minimum to maximum in a constant tension mode and that is operable to be switched between a normal mode and a constant tension mode for raising and lowering an object supported by a cable on the winch between a relatively stable platform and a surface undergoing vertical wave motion relative to the platform, said lever control being capable of switching the system between the normal and the constant tension mode, comprising:

• a single, manually actuated control lever means positionable for controlling the winch for (1) hoisting and lowering in the normal mode, (2) varying the cable tension of the constant tension mode, and (3) activating a constant tension mode selection circuit to allow switching between the normal mode and the constant tension mode;
• said control lever being positionable into a commit-to-constant-tension position when activating the constant tension mode selection circuit;
• means responsive to the control lever being placed in the commit-to-constant-tension position for activating the constant tension mode selection circuit to allow switching between the normal mode and the constant tension mode;
• and
• means responsive to a change to minimum cable tension for automatically switching the winch from the normal mode to the constant tension mode when the constant tension mode selection circuit is activated.