The first of 48 monopiles was installed in the Ijsselmeer, and all foundations are expected to be in place by the end of April.
Siemens was handed the turnkey contract in 2013 and will also deliver 48 3MW turbines to the project site, north of Amsterdam.
The first wind turbine in the IJsselmeer is expected to be operational by July, with full commissioning expected in early 2016.
Westermeerwind is the country's largest near-shore wind project. It is next to the Noordoostpolder onshore wind farm, where a further 38 Enercon 7.5MW turbines will be installed along the dike.