Very-low-head hydropower constitutes a large untapped renewable energy source, estimated at 1 GW in the UK alone. A new type of low-impact waterwheel has been developed and tested at Abertay University in Scotland to improve the economic viability of such schemes. For example, on a 2•5 m high weir in the UK with 5 m3/s mean flow, one waterwheel could produce an annual investment return of 7•5% for over 100 years. This paper describes the evolution of the design and reports on scale-model tests. These show that the new design harnesses significant potential and kinetic energy to generate power and handles over four times as much water per metre width compared to traditional designs.