Damen Shiprepair Amsterdam (DSAm) has concluded major modification works on the Sea Installer. The principle scope of work involved the extension of the main crane boom, giving the A2SEA-owned offshore wind farm installation vessel increased reaching capacity: a pertinent point considering the trend of the increasing size of offshore wind turbine components. Other work comprised structural modifications as a consequence of the larger crane.
Photo courtesy: Damen
DSAm, part of Damen Shiprepair & Conversion, began the work by removing all crane-related components including the boom, boom rest, A-frame, winch and hook block pockets from the vessel. A2SEA supplied the new A-frame and boom extension. Niron Staal, also part of Damen Shiprepair & Conversion, supplied the new boom rest, hook block pockets, trolley rail and support stools.
“Then, after slight cooling, the welding itself needs to take place at the correct temperature in a protected environment. For this, we constructed air-tight welding tents.”
Once complete, the weld in question was cooled prior to non-destructive testing after 48 hours. “We also performed our own initial checks after 24 hours in case any additional welds were needed. The main point with S690 is that you cannot rush things. If you go too fast, it can set you back 3 days.”
Two mobile Mammoet cranes lifted the extended crane boom back onto the vessel. To create a stable lifting foundation – allowing for a maximum of 0.3 degrees of tilt – the quayside was levelled prior to the vessel’s arrival at the yard. This required laying no less than 800 cubic meters of sand, topped off with 750 dragline crane mats.
The bigger crane also needed a bigger winch: DSAm replaced the existing winch with a larger, 900-ton capacity, winch. This included all the necessary adjustments of the electrical, hydraulic and cooling systems. The vessel’s main mast also needed structural modifications.
With the 132-meter long vessel at the yard, DSAm also executed various standard maintenance jobs such as painting, pipe renewal and thruster inspection.
The smooth running of the entire project was facilitated by the joint efforts of the DSAm and A2SEA personnel. “It has been a pleasure to work with the ship’s crew,” concludes Mr Van Dam. “There has been good communication throughout and this has helped us in many ways. For example, their involvement in adjusting the ship’s ballast tanks during such a heavy lift was crucial.”