Jan De Nul has installed half the turbines at the 600MW Kriegers Flak offshore wind project off Denmark, with 36 more to go.
The end of the installation campaign of the 8.4MW machines is planned for mid-June.
Jan De Nul, Siemens Gamesa and Vattenfall started installing the hardware four and a half months ago.
The offshore wind farm will be the largest in Denmark when fully operational at the end of the year.
Jan De Nul project manager Bert Reynvoet said: “We are proud that we can tick off this milestone nicely on schedule.
“All 72 wind turbines must be installed within a period of 4.5 months.
“Our customer’s wishes are paramount and despite the challenging winter weather conditions in the Baltic Sea, COVID-19 and challenging soil conditions for our jack-up installation vessel, we have managed until today to strictly adhere to the installation schedule.
“Thanks to the commitment, flexibility and professionalism of our co-workers.”
For the first time since its expansion in 2018, the port of Roenne on the Danish island of Bornholm is serving as marshalling harbour for the construction of an offshore wind farm.
The components of the Siemens Gamesa wind turbines are delivered from Denmark’s mainland.
In Roenne, the various parts are assembled. In sets of four wind turbines, they are loaded on board Jan De Nul’s jack-up installation vessel Vole au vent, after which the vessel sails to the offshore installation site off the Danish east coast.