It was a rare and impressive sight: Two mighty lock gates from the ports of Bremen stood one behind the other in the dry dock at Lloyd Werft over the past few weeks. Now one of them is ready for use again: The reserve gate of the Kaiserschleuse lock has completed its extensive “cure” at the shipyard and is back in place - with modernized technology and new sustainable conservation, it is now ready for its next literal deployment in the Kaiserschleuse lock.
The 2,500-ton steel gate - 57 meters long, 11 meters wide and 21 meters high - has been extensively overhauled since January. In addition to replacing all four hydraulic cylinders, each of which weighs around 12 tons, the seals in the filling gap were renewed, sliding plates replaced and new cables for the undercarriage load measurement installed. A lot of work was also invested in the preservation of the colossus - to prepare the door for the next round of harsh operating conditions.
Millimeter work in XXL format
To manoeuvre the gate out of the dock and transport it to its usual waiting position, the water level in the overseas port was deliberately raised to around 4.30 meters (chart datum) on Monday - a measure that was carefully coordinated in advance with all port residents so that they could, for example, loosen the ship ropes slightly when the water rose and then tighten them again. Floating out the gate itself, which weighed several tons, was ultimately millimetre work on an XXL scale: “You don't just move a lock gate like that,” says Michael Staar, Team Leader Technical Installations at bremenports: “This is precision work on a large scale: even despite the water level increase, we had just 18 centimetres towards the jamb of Kaiserdock I, i.e. almost exactly the proverbial hand's breadth of water under the keel or under the gate. That's exactly how the whole project was calculated beforehand and agreed with everyone involved in the project - but 18 centimetres with a total gate height of 21 meters doesn't necessarily give you much leeway.”
Break for the senior lock gate
While the younger Kaiserschleusen gate, after being hooked by the BHV Athlet floating crane and 2 tugboats due to the wind force and transported from the dock back to its original position, is now ready for its next use, the much older reserve gate of the northern lock - built in 1931 - will remain in the dock for the time being. Work on the historically valuable component, which weighs around 1,100 tons, will continue after an interim break: The Polarstern will now be docked directly in front of the gate and put through its paces. Work on the research vessel and the north lock gate is now being carried out at the same time. The short delay caused by the interim docking is not a problem: the next literal use of the north lock gate is not planned until late summer - enough lead time to complete all the necessary work here too.
Regular maintenance for safe lock operations
With the scheduled replacement and thorough maintenance of the lock gates, bremenports ensures the long-term operational safety of the lock facilities in Bremerhaven. By regularly switching between operating and reserve gates, necessary inspections and repairs can be carried out with the necessary technical effort and in a controlled environment - an investment in the reliability of the maritime infrastructure and the efficiency of the ports of Bremen.
