The 4P charity based in Spain have developed a moored rocking boat, called the "Wave Rocker", which is a new type of device promising to extract energy from wave power. The concept uses a floating catamaran optimised to be laterally stable but rock longitudinally. A mass is free to move up and down the length of the deck, acting as a piston as it reaches each end of its travel. Fluid displaced by the piston generates power. Alternatively, the piston could be replaced by a magnet or armature running through coils.

The mooring line has an elastic section to magnify the effect of the moving mass on deck. As an oncoming wave lifts the front of the craft, the centre of gravity moves back and the mass on the deck moves towards the stern, delivering the first power stroke. The craft is then lifted to the top of the wave and levels out. As the wave passes, the craft moves down the wave slope, tilting forwards. Its motion is increased by the tension in the mooring rope drawing it downwards. The moving mass moves towards the bow, delivering the second power stroke as the craft runs into the next wave and digs into it. The passage of the subsequent wave repeats the cycle. The inventors believe that the effect could probably be further enhanced by adding vortex drag foils to the hull or adopting a special hull shape and replacing the elastomeric rope with a fixed rope attached to a tensioning device.

The team of inventors is working with several institutions in the UK equipped with wave tanks. They are looking for investors, partnerships, or other input that can be used to help progress the idea further. It is interesting to note that wind-generated waves on the ocean surface have a total estimated power of 90 million gigawatts worldwide (DTI – Wave Energy). Due to the direction of the prevailing winds and the size of the Atlantic Ocean, the UK has wave power levels that are among the highest in the world. Wave energy has the potential to provide as much renewable energy as the wind industry, but the development of wave technology is currently at the same level as the wind industry was 10 years ago.