Heerema installs test turbine

Heerema’s heavy lift vessel Aegir has installed its first Delft Offshore Wind Turbine Concept (DOT) which was connected by a Slip Joint. The DOT wind turbine is located at the Princess Amalia wind farm off the coast of IJmuiden, the Netherlands and has been mounted on a monopile foundation.

The complete wind turbine was picked up in a single lift by Heerema’s lifting vessel  
Aegir  from the quayside of Sif Group's Rotterdam facility and transported towards its designated location. The fully assembled turbine was installed by the vessel using Dynamic Positioning 3. The installation of the wind turbine took less than 1 hour in total.

The installation featured a Slip Joint, which is an alternative connection between an offshore wind turbine and its foundation. The connection is based on friction, where the weight ensures a firm and stable connection. Installation is done by simply sliding the wind turbine over the monopile without the use of grout or bolts. This mechanism  is designed to reduce the costs of material, equipment and personnel as well as allowing for a shorter installation time. It is the first time a slip-joint connection is deployed offshore.


The Slip Joint Offshore Research project (SJOR) was initiated by DOT BV late 2016 and is a collaboration between the research partners; TU Delft, TNO, Van Oord and Sif group and project stakeholders; Eneco and Heerema Marine contractors. The consortium aims to reduce the costs of Offshore Wind and to strengthen the Dutch offshore Wind energy sector.

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