28. November 2011
The down-scaled 1:6 test model met the full scale extreme weather and sank during last Sunday’s extreme storm “Berit”. The turbine is located at the test site, and has been surveyed by ROV. There were no visible structural damages, and the test model will be recovered soon. The time needed to repair it will then be assessed. Even though the effect of the extreme storm “Berit” would not be a problem for a full scale turbine this incident will certainly give us important and valuable experience. The direct cause leading to the sinking of the Sway prototype was extreme weather exceeding the design parameters. Due to its size, the scale model was designed for a maximum wave height of 4,0m (Hs=2,0m) which represents full scale waves of maximum wave height 26,0 meters. Data collected by NREL (National Renewable Energy Laboratory) at the site shows a maximum wave height for the scale model of 6,3 meters, which would translate to 40,6 meters in full scale. These wave conditions are extreme. In comparison, the North Sea the “Hundred year wave” is 30m. This extreme wave height combined with a storm surge (high water level) caused water to enter into the tower through the inlet pipe for the power cable (the J-tube) causing the tower to fill with water. The J-tube will be extended to eliminate this risk before the 1:6 scale model is re-deployed. See link to the full press release to the right under "Related files":



SWAY AS /  C. Sundtsgt. 51 / 5004 Bergen / Norway / Phone: +47-55220900 / E-mail:post@sway.no