When you think about concrete, using it to make canoes might not be the first thing to come to mind. Yet the Concrete Canoe Regatta in Germany shows that it is possible, and results in some very creative solutions. The team of ETH Zurich won the prize for best design innovation, for their canoe SkelETHon, which, as the name implies, has an intriguing skeletal construction.

SkelETHon weighs 114 kilograms (250 pounds) and is 4 metres (13 feet) long. The most interesting feature is its skeletal construction, which was designed to reduce the weight of the boat as well as the amount of material necessary, all the while maximising the stiffness of the boat.

The skeleton was made by 3D printing a plastic formwork, which weighed about 4 kilograms (9 pounds). In this mound, steel fibre reinforced concrete was poured. Making it with another fabrication processes, such as CNC-milling or hot wire cutting, wouldn’t have been possible.

The skeleton has a precise, high-resolution surface texture, with details as small as half a millimetre, was transferred to the concrete skeleton to increase the contact area with the outer skin of the canoe, a layer of 2 to 3 millimetre-thick waterproof concrete. Some of the “bones” are no more than 15 millimetres thick.

The Concrete Canoe Regatta is a biannual two-day long concrete canoe race that takes place in a city in Germany. This year, the regatta was held from 9-10 June, and drew in 1,000 participants and 90 boats from all over Europe. ETH Zurich won for the 3^rd time in a row the award for design innovation. The canoe was made in a collaboration between ETH Zurich, Digital Building Technologies (DBT), and the Physical Chemistry of Building Materials (PCBM) Group.

For another concrete canoe at Materia, click here

Photos: ETH / DBT