Dutch maritime research institute MARIN has been working on solutions to avert collisions between ships and wind turbines, following an incident involving the bulk carrier Julietta D this year, which initially collided with a tanker before hitting a transformer platform and a turbine foundation for the Hollandse Kust Zuid wind farm currently under construction.
A group of 20 experts from MARIN and the wider maritime sector developed three concepts for maritime crash barriers between shipping routes and windfarms during a February workshop. The first concept involves a string of surface buoys secured by drag anchors. The second concept comprises a smart suspension net between fixed poles and the third is an anchored underwater hook line designed to catch the anchor of the drifting vessel. MARIN built scale models of all three solutions and ran tests in its offshore basin last week to see if the barriers were capable of deflecting a scale model comparable to the Julietta D in storm conditions.
The first results are said to be promising. “We’ve established that all three concepts are able to intercept the vessel,” said William Otto, MARIN’s offshore project manager. “The drag anchors of the buoy string dissipate the drift energy evenly, so that the vessel stays afloat across the waves. The anchored underwater hook heads the vessel into the waves, so reducing roll. That means the vessel remains in place while being exposed to relatively low forces. The smart suspension net initially showed too much droop, but with a bit of fine-tuning we were able to get this functioning too. Over the coming months we will go on to assess the various pros and cons of these systems,” he explained.
According to MARIN’s research, some 2500 wind turbines are set to be installed in the North Sea in the period to 2030, taking the risk of a turbine being hit by a ship to around 1.5 to 2.5 times a year. The various concepts and all test results are being shared as an open innovation project to enable further development of the most promising concepts. Representatives of the Dutch maritime and offshore organisations were involved in this project, including Bluewater Energy Services, Mooreast, Vuyk Engineering, Heerema Marine Contractors, Boskalis, GustoMSC, KRVE (Rotterdam Boatmen), Pinkster Marine Hydrodynamics, Huisman Equipment, Orca Offshore en SBM Offshore.