MEASURING: THE PULLING LOAD AND PAID-OUT LENGTH OF WINCH WIRES

In 1980, the Netherlands company Observator B.V. had to devise a means of measuring the pulling load and paid-out length of the wires of positioning winches in vessels to be used, under difficult conditions, for placing with utmost accuracy pier foundations and seabed mattresses for the Eastern Scheldt storm surge barrier. Four of these winches were in the pier-lifting vessel Ostrea and two were in the block-mat laying pontoon DOS 1. The article gives brief information on the measurement of the pulling load and paid-out length which serve as standards for manoeuvring when hauling the Ostrea. This is followed by a detailed description of the similar arrangements for the two 900-kN winches in DOS 1. Each winch has a preamplifier box collecting the sensor signals, which are transmitted to a central unit (in the engine room> where they are processed, the data being distributed to the various indicators and to a computer system in an accompanying dredger. The load is measured by two pressure load cells on each winch, which also has a wire-length measurement device based on counting the revolutions of the seizing installation guiding-sheave and the activation of a pulse generator. The systems are described with the aid of block diagrams, drawings and photographs.