HSE


nearby mooring legs can take up the slack. In this way, the vast kinetic energy of the intruder can quickly be absorbed. The vessel is stopped and nearby wind turbines are kept secure. Nor are surface buoys the only project that Otto and his team are busy perfecting. By using vast suspension nets that are 1,500m long and tensioned between two monopoles, MARIN hopes to stop errant vessels in their tracks here too. Another strategy involves underwater hooklines, whereby a ship’s anchor is looped around a wire floating five metres above the seabed. Whatever the system, at any rate, it’s clear that MARIN hasn’t simply stuck to the theory. On the contrary, Otto explains how his team tested their theories vigorously, using scale models in a giant basin. A 176m drifting vessel, for example, was represented by a 4.4m wooden model. “At this scale we can measure realistic ship motions and line forces,” Otto adds, “as at this scale we have decades of experience for testing all kinds of mooring systems.” A fair point: MARIN’s bread-and-butter has, for decades, been testing moored ships, work that shares certain similarities with the North Sea’s current predicament. It helps, too, that tinkering with designs was straightforward due to their smaller scale. That meant, for instance, that MARIN could quickly identify the problem of nets getting trapped beneath vessels – a problem handily solved by integrating buoys, keeping the nets floating nearer the water line.


A step forward


The ultimate question, of course, is how successful MARIN’s models actually were at stopping runaway ships. The main headline here is essentially positive. As Otto laconically puts it: “The barriers were able to catch the vessel and bring it to a standstill.” Consider what MARIN’s achieved so far and this seems like a fair assessment. Though its barriers haven’t yet been tried out in the wild, they were able to halt loads weighing between 150–300t. Even so, Otto is careful not to overstate his employer’s triumphs. For one thing, the barriers weren’t tested to stop specific vessels in specific weather conditions. Given the North Sea’s volatility – either in terms of wind or waves – that’s clearly something that’ll need attention eventually. More broadly, MARIN hasn’t yet investigated how these barriers would be installed in the real world, nor how a stricken vessel might be untangled from all those nets and anchors. As Otto stresses, MARIN has to be careful “not to claim success” based on what are only tentative first steps.


All the same, speak to others at MARIN and it’s clear that industry insiders understand the potential of their work. “We have invited shipping companies, turbine operators and organisations such as the Coast Guard to the demonstration day of our open innovation project,” says Bas Buchner, MARIN’s president. “They responded positively.” The team’s work is being recognised in other ways too: the Dutch Association of Shipping Companies nominated them for a prize this year, recognition of what Buchner calls their “proactive and innovative” work on ship safety. Yet, as Buchner continues, more enthusiasm is needed if the North Sea is ever to be crisscrossed with mooring legs for real. A maritime research institute, MARIN is focused on just that: research. But actually getting barriers built commercially requires a profit-oriented firm to push development forward. To that end, Buchner is considering the creation of a ‘joint industry project’ whereby industry and government can collaborate to finally keep vessels and turbines safe at sea. Given how awful that Monday back in January 2022 almost was, that’s surely just as well. ●


World Wind Technology / www.worldwind-technology.com


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