| 摘要 |
A carrier for cargo or personnel is transferred between an offshore platform and a landing platform on a vessel while subject, one with respect to the other, to vertical and lateral movements due to waves and wind within an envelope of motion. When the carrier is on the offshore platform, it is lowered by a cable from a constant tension level lifting winch to a point above the envelope of motion by the landing platform on a vessel. A trailing end of this cable is coupled to the cable of a downhaul winch having variable constant tension levels on the vessel. Slack is eliminated in the coupled cables and the carrier is caused to rise and fall with the movement of the vessel through a preestablished constant tension level by the lifting winch. Constant tension is developed in the coupled cables when the vessel moves toward the carrier within the envelope of motion while the downhaul winch is set at a higher tension level and zero winding speed. The carrier is then drawn onto the landing platform by energizing the downhaul winch to a desired winding speed at the higher constant tension level. Slack is eliminated from the coupled cables by energizing the lifting winch when the carrier and the lifting platform approach each other. The carrier is retained on the landing platform by energizing the downhaul winch to the higher constant tension level. The downhaul winch is then energized to a tension level less than the tension level of the lifting winch when the carrier recedes away from the lifting platform and when the carrier is lifted from the landing platform by the lifting winch. The cable take-up velocity is maintained at a value exceeding the vertical relative motion between the platforms.
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