January/March - Export Cable for the Baltic 1 offshore wind farm

After a delay on the Baltic 1 export cable, due to a delay in the production of the cables in 2010, JD Contractor A/S was able to finish the cable installation in the final months of 2010 and the beginning of 2011.

Date: September & November 2010, January-March 2011

Client: NKT-cables GmbH

Export Cable for the Baltic 1 offshore wind farm

The German TSO 50 hertz awarded NKT-cables GmbH the contract for the supply and installation of the export cable for the first German commercial offshore wind farm, Baltic 1, in the Baltic Sea off the coast of Germany. At the time of installation the 245 kV AC cable was both the largest and heaviest subsea cable in the world with an outer diameter of 235 mm and a weight per meter of 114 kg.

Initially JD-Contractor A/S was contracted by NKT-cables as the lead subcontractor responsible for pre-excavating, cable installation and post-burial of 4 X 15 km sections in the Baltic Sea and a 2 km inshore section in the Breitling area. The installations were to be performed by the vessels: Cable Installation Barge Henry P. Lading, and the diving vessels C/S Cable One and M/S Honte.

However, due to problems with the production of the cable, the project was delayed approximately half a year. As JD-Contractor A/S vessels were then occupied with other commitments, JD-Contractor A/S were forced to suspend the cable installation work after installing the first cable section in the Baltic Sea in September 2010. Another contractor was brought in by NKT-Cables to take over the cable installation.

As a result of the problems in production and an emergency cutting of the cable performed by the new contractor, the cable in the Baltic Sea had to be installed in six sections instead of the original planned four. Consequently as soon as there were available resources, JD-Contractor A/S  was asked by NKT to resume parts of the installation work.
On short notice C/B Henry P. Lading managed to install a second section of the cable in the Baltic Sea between two other projects in November 2010, and a third and fourth section of the cable in the Baltic Sea together with two joints between January and mid February 2011.
On top of this, JD-Contractor A/S made three joints at the PSV Triton and the inshore Breitling section with an adapted barge setup in January and February 2011.

Altogether, JD-Contractor A/S ended up installing four out of the six sections (50 out of 60 km) in the Baltic Sea, five joints as well as the inshore Breitling section.
Also, JD-Contractor A/S pre-trenched approx. 16 km of the cable route with M/E Jette Saj, and performed post-burial by means of jetting in the cable with M/S Cable One, M/S Vina and M/S Honte.

Due to energizing of the cable, the burial by JD-Contractor vessels had to be aborted in March 2011.

Work carried out by JD-Contractor A/S:

  • Pre-excavation.
  • Instalation of 50 out of 60 km export cable.
  • Instalation of the in-shore Breitling section.
  • Five joints were made.
  • Post-burial of the export cable. 

Vessels used:

  • C/B Henry P. Lading
  • M/S Vina
  • C/S Cable One
  • M/S Honte
  • M/S Marcos
  • S/B Victor
  • T/B Naja
  • M/V Lille Björn
  • M/E Jette Saj
  • PSV Olympic Triton
  • Lots of smaller boats and barges