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Wave heights and accessibility

 

The accessibility of an offshore wind turbine by ship is largely determined by the height of the waves. Weather situations with a significant wave height (Hs) of more than 1.5 m are designated as weather days, and in such situations the transfer of service personnel from a workboat to the access ladder of the offshore wind turbine is too risky. Even using special access systems that can compensate for the vessel’s movements, accessibility is still limited to 2 m significant wave height.

 

The comparison of wave and sea condition data from FINO 1, FINO 2 and FINO 3 substantiates the different sea conditions in the North and Baltic Seas in 2017 and also over a longer period of time at these stations. Both evaluations show that the installation, maintenance and service of offshore wind farms pose great challenges with regard to the adverse effects of the sea conditions in the North Sea, combined with reduced access compared with the comparatively calm Baltic Sea. These access restrictions play an important role for the installation, commissioning and service.

 

 

 

 

Distribution of average significant wave heights for FINO 1, FINO 2 and FINO 3 for 2017
Data sources: [BSH Forschungsplattformen]

 

 

 

 

  

Distribution of the distribution of average significant wave heights for FINO 1, FINO 2 and FINO 3 for 2004 - 2017

Data source: [BSH Forschungsplattformen]

 

 

The yearly variations of the wave measurements for the North Sea (FINO 1) and Baltic Sea (FINO 2) are shown in the following figure. It is once again very clear that the lower average wave height is to be found in the Baltic Sea. Missing data indicates measurement system failures. It is readily apparent that in summer there are relatively low wave heights at both locations. Since there are lower wind speeds in summer and also better light conditions, most operators plan their regular maintenance activities for the summer months.

 

 

 

Monthly comparison of the average significant wave heights in 2017

and the average from 2013 to 2016 at FINO 1,FINO 2 and FINO 3

Data source: [BSH Forschungsplattformen]