Dantysk OWF
- Seabed survey and levelling

The challenge

Vattenfall, the operator of the Dantysk offshore wind farm, approached SubC Partner with an urgent request to survey and level the seabed in preparation for the Dantysk accommodation platform (OAP) jacket structure.


The purpose of the work was to ensure that the seabed was at a certain depth and flat at the footprint of the OAP jacket structure. The requirement for the flatness was less than delta 10 cm with an edge slope of 1:6.


SubC was asked to provide a swift package solution for immediate offshore operation. The solution was based on using a DP2 vessel equipped with a suitable active heave compensated crane to operate the bespoke hydraulic dredging grab. The survey solution consisted of a state of the art multibeam/sonar with an ultra-high 128 x 128 beam resolution. The survey equipment could provide continuous monitoring and 3D real-time measuring of the actual seabed depth. A total of approximately 200 m3 of soil was dredged to a high degree of accuracy.

The mobilization was performed very fast, especially considering the bespoke dredging and complex multibeam survey system. The operation itself consisted of few offshore operation days including in-survey and out-survey reporting.

Survey & Levelling