University CrestEdinburgh Wave Power Group

Last update by: Jamie Taylor 11th December 2009


Document archive

Stephen Salter

The Duck

Curved Tank
Wide Tank

Tank seas

Robert Clerk

Flow Table
Sloped IPS Buoy
The Dervish 
Variable pitch turbine 
Oil hydraulics
Rain Making
Tidal current rotor 

The Workshop



The Institute
The School
The University




These pages are largely made up of un-published information from the Edinburgh Wave Power Group which is now incorporated in the Institute for Energy Systems of the School of Engineering at the University of Edinburgh. During the 1970s and 1980s we also referred to ourselves as the 'Edinburgh Wave Power Project'.

The Wave Power Group at the University of Edinburgh dates back to 1974 - the year that Stephen Salter invented the 'Duck' as a means of converting into electricity some of the abundant natural power that arrives as ocean waves on our western shores.
1974: The first duck. Stephen Salter on right with David Jeffrey the co-founder of the Wave Energy group.


Evolution of Duck full-scale engineering design

The Duck is a crest-spanning, spine-mounted, slack-moored, deep-water, floating, electricity-generating, terminator. Tank tests showed that it could capture energy from regular waves with great efficiency. Development of 'smart' dynamometers using force-based transducers with analogue electronics showed how to get more and more power out of mixed and ever-changing sea-states. The final goal was to get near to the utopia of real-time 'complex-conjugate' control. The engineering challenge was how to build these ideas into a system that would convert the raw sea power into electric current suitable for grid connection and survive at sea. As the 'power-take-off' designs evolved, they gave birth to a new generation of high-pressure oil-hydraulics that now finds much wider application.

1974: first sketch, as published in Nature.
1979: sealed gyro-tube,
1993: single ring-cam & twelve-ram active joints


1984: Robert Clerk surrounded by the designs for his 'trilink' machine.
The development of the duck concept so that it might compete economically with conventional sources of energy required several new technologies. Above all, there was a need for very high efficiency high-pressure bi-directional oil hydraulic transmissions that could implement the advanced control algorithms required to get the most energy out of waves. With the arrival of Robert Clerk and his ground-breaking designs, we started in the early 1980s to develop a new generation of high performance hydraulic machines. Building on that experience, a new company called Artemis Intelligent Power Ltd. was founded in 1994 by Win Rampen and Stephen Salter to develop the next generation of hydraulic machine. They call this new technology 'digital hydraulics'.

From the beginning, wave energy research needed a new generation of high-fidelity test tanks, and concurrently with the invention of his Duck Stephen Salter created the first 'absorbing' wavemaker. This became the foundation of our accurate and highly repeatable narrow tank work and led in late 1977 to the revolutionary Wide Tank. In 2001 we had to dismantle the Wide Tank, as the site was required for a long-delayed building project. We replaced it with the novel and user-friendly Curved Tank. It was built by our spun-out colleagues at Edinburgh Designs Ltd, the world leaders in wave-making and test-tank design.

1975: Control bench for the old narrow tank. Real time multi-axis analogue control - the best thing for optimising a wave energy device. 1983: Chris Retzler and Andy Knox flying the spine model in the wide tank. Computers had taken over. 1978: Duck model on the surging heaving rig meets 50 year wave. As good as it gets in a narrow tank. 2002: First 'sneak' wave in the Curved Tank - the most intimate of multi-directional tanks.