Patent ID: 8297597
Filing Date: 2012-10-30
Classification: B63B,B66C,B66D

Abstract:
1. A method for lift compensation of an item connected by a rope to a lifting device disposed on a vessel, wherein the lifting device comprises a heave compensator arranged to control a speed of a rope drum, the method comprising: with the heave compensator, controlling the rope drum of the lifting device according to a calculated contribution comprising a heave term and a deviation term, wherein the deviation term is calculated from a difference between a current position of the item and a selected position of the item; monitoring a force on the rope; and bringing in a correction term into the calculated contribution for the heave compensator when the force is above a first upper limit or below a first lower limit, wherein the correction term is determined to feed rope faster from the rope drum when the force is above the first upper limit and to tighten the rope when the force is below the first lower limit.