The device works like a typical linear generator in which a set of magnets mounted in a translator is moved up and down inside multiple coils of wire of an armature.  However, there is a crucial difference with Snapper: alongside the armature coils is a second set of magnets of alternating polarity.

CAD Snapper In Tank

These armature magnets prevent the translator magnet assembly from moving up and down smoothly in relation to the armature. Instead magnetic forces between the armature and translator repeatedly couple the two sub-assemblies together until the external force is able to overcome it.  This results in a series of faster movements (faster relative movements between armature and translator) more suited to classical electrical generation.

CAS Snapper Spring Detail

Technical papers

A high Force Density Generator Using a Slipping Magnetic Coupling (PDF, 534kB)

E.Spooner, J.R.Bumby, R. Morgan, J Grimwade


Snapper - an efficient and compact direct electric power take-off device for wave energy converters (PDF, 1.1MB)

E. Spooner, J. Grimwade


Hydrodynamic and Electromechanical Simulation of a Snapper Based Wave Energy Converter (PDF, 9.33kB)

H. Bailey, R. C. Crozier, A. McDonald, M. A. Mueller, E. Spooner, P. McKeever


UK Magnetic Society – Technologies for Renewable energy “Snapper” Wave Energy Capture – The Mechanical Challenge (PDF, 252kB)

P. McKeever, C. Ng, M. Taylor,  E. Spooner,  M. A. Mueller, R. C. Crozier