Clever anchor could help float new offshore wind turbines

Vryhof has successfully completed extensive field tests of its Stevshark Rex anchor, which has radically new fluke and shank geometries, in close collaboration with Woodside Energy, one of Australia’s major operators.

“We were very interested in getting the test results of the Stevshark Rex anchor in remote and challenging territories,” said Amy Rathmel, geotechnical engineer with Woodside Energy.

“This includes the Angel Field in the North-West Shelf of Australia with complex cemented soils of carbonite origin or calcarenite to limestone rocks. These geological settings can be quite brutal and very hard, so difficult for an anchor to embed.”

Over a period of several days, Deep Sea Mooring Australia coordinated and executed tests with the anchor.

The 18 tonne Stevshark Rex anchor with 7.2 tonnes ballast was tested in one hundred meters of water at four different locations, each with their own ‘extreme’ soil characteristics.

For the execution of the tests, Farstad’s Far Scorpion, having a bollard pull of 251 tonnes, was deployed.

All of the tests were successful with the holding power of the Stevshark Rex exceeding all expectations.

Over the last few years the anchor has also been tested at a total of 15 tests carried out at three locations in the North Sea famed for its stiff clays.

In early 2017, the new anchor was used in the United Arab Emirates by a rock cutter suction dredger on cemented soils. All tests have achieved similarly positive results.

By Anne-Marie Causer