Ridderinkhof Wave Winch is a high dynamic escort winch, started as LNG winch, that keeps the line tight during all operations and all movements of the tug. At line forces higher than the setpoint of max line force, the line will veer out enough length at very high speed until the situation is safe again, without causing the line to break or become slack.
Until recent years the offloading of LNG tankers have taken place in relatively sheltered conditions in harbours and more shielded conditions around terminals. In the newest Offshore LNG import and export terminals, these operations are carried out in real offshore conditions. With related higher waves of 3 meter plus. Birthing operations by tugs provided with winches that are non compliant to these harsh conditions are costly, ( waiting time for better weather) and/or dangerous ( breaking towing lines causing uncontrollable tankers very close to LNG jetties ). The oceanic waves plus the effect of returned (reflected) waves cause a very unpredictable and choppy water surface in which the tugs have to guide the LNG tankers to moor safely to an LNG jetty.
The answer we defined to this, is the Ridderinkhof WAVE WINCH ®
With a normal drive system, a tug movement or roll towards the tanker is causing a slack wire and the hauling speed of a normal escort winch drive system is too slow to follow. Typical wave winch hauling speed is over 100 m/min, enabling to automatically follow any forward/backward movement of the tugmaster and keep the line tight.
The master can adjust and set the max line force proportionally, because all situations and tankers are different and not all the tankers are capable of withstanding the (high) line force that the tug and winch is designed for.
The WAVE WINCH types are available for 75, 105 and 130 tons dynamic full continuous render/ recover pull. The whole range is available with electrical frequency drives or with hydraulical drives. The winches can also be operated in the traditional way; manually hauling and veering and towing on the brake. The line force of the holding brake can be selected between 100 ton and 250 tons. The system is fully automatically, the master does not have to worry about the winch! Captains working with our wave winches stated that this will become the new standard, also for non LNG applications.