When rock turns out to be clay

The loads from the 40-meter-high wing sail prototype in Landskrona will be handled by a climate-improved concrete base with underground pillars. But when drilling for solid ground, there was only clay.

“We almost found oil!” was the description by an Oceanbird colleague of how deep we have drilled in search for solid ground. Early geological investigation showed that there most probably was solid rock 35 meters down, which is needed to attach the wing sail prototype to the ground. When the contractor NCC conducted the drilling, the “solid rock” turned out to be far from that, even when continuing 70 meter down.

”Apparently there was no solid rock in the location we have chosen. We had to rethink, redesign the concrete foundation and find a solution to the problem” says Oceanbird´s Senior Product Manager Jonas Alvan.

New solutions

Instead of 16 long steel piles, the design was changed to approx. 70 shorter concrete piles and an extra wide concrete foundation. Together, they will carry the load of the complete wing sail in strong winds, but also when tilting the complete wing sail. Thanks to the fast re-design, this endeavor will not affect the overall prototype time plan.

”There are always challenges in every project. It’s a matter of finding new solutions, move on and do the best of the situation,” says Jonas Alvan.

Jonas Alvan
Jonas Alván, Oceanbird in front of the piles for the concrete base, which will be made of climate-improved concrete.
Daniel Månsson, Project Manager at NCC
Daniel Månsson, NCC

Climate-improved concrete

The 550 m3 concrete base is made of concrete with 23% less environmental impact. The concrete is climate-improved by replacing parts of the cement with other products with similar properties.

“In this case, it is blast furnace slag from the steel industry and fly ash from coal combustion. By doing this, we save about a quarter of the emissions, which in this case corresponds to about 47,300 CO2e, while having the same strength of the concrete”, says Daniel Månsson, Project Manager at NCC.

Assembly continues

The land-based wing prototype is now being assembled Oresund Drydock in Landskrona. It will be an opportunity to test safety philosophy, automation and assembly before putting a wing sail onboard the vessel Tirranna, and also work as a site for crew training and customer visits.

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