The Baltic Sea island to the north-east of Bornholm is facing a mammoth project: the historic natural harbour between the main island of Christiansø and Frederiksø is being completely renovated. Work has already begun and is expected to last until the second half of 2026. Sailors must be prepared for significant restrictions during the renovation. There will only be limited berths available for leisure boats.
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Meticulous dismantling and reconstruction
The renovation of the harbour, which is over 340 years old, is being carried out with the utmost care. Every single stone of the old piers is numbered, marked and temporarily stored. The rotten wooden planks below the waterline are then replaced with new oak. This involves the use of so-called fleet oak, which is between 120 and 210 years old. Oak wood in this age category is particularly suitable for long-term use under water. When rebuilding the harbour, meticulous care is taken to ensure that every stone is placed exactly in its original position and at the same angle. This meticulous approach is intended to ensure that the harbour retains its historical appearance once the work is complete.
Restrictions for sailors
At the moment, the working pontoon is not yet a major hindrance to operations. But Søren Thiim Andersen, the manager of the Ertholmene Islands, to which Christiansø belongs, warns: "In a month or so, it will be moved to the other part of the harbour, where the leisure boats normally moor. As a result, the number of berths for yachts will be severely limited this year." This restriction will hit the popular island harbour hard. According to official figures, around 2,000 sailors visit Christiansø every year with their own boats. The harbour is accessible from both the north and the south in all weather conditions, making it a popular port of call in the region.
Technical challenges and schedule
The renovation work represents a special challenge for the contractor MT Højgaard. Project manager Thomas Mathiasson explains: "It's an extensive project and a little different to what we're used to. But it's exciting and makes sense when you're working in a place as historic as Christiansø." A huge work pontoon was towed to Christiansø for the work. Specialists are working on it with cranes and excavators to save the centuries-old harbour from decay. The renovation is scheduled to take one and a half years and should be completed in the second half of 2026.
A look into the future
Despite the temporary restrictions, the islanders are optimistic about the future. They are looking forward to their harbour shining in new splendour - exactly as it looks now, but in a modernised and more stable version. The careful renovation will ensure that the historic character of the harbour is preserved, while ensuring its functionality and safety for generations to come. For sailors and visitors, this means that once the work is complete, they can look forward to a completely renovated harbour with an unchanged appearance.
