A wave energy converter system comprising: first and second bodies (100,200) which can move relative to each other in response to waves; a power take off device connected between the first and second bodies (100,200) to convert their relative motion into useful energy; a programmable control compute including means for selectively controlling forces between the PTO and the first and second bodies; characterized by: a sensor, external to the WEC, for sensing waves incoming onto the WEC upstream of the WEC and supplying signals corresponding to the incoming waves to the programmable control computer for generating signals predictive of the effect of the incoming waves on the WEC; means responsive to the movement of the first and second bodies (100,200) for generating signals indicative of their actual movement and supplying signals indicative of the actual movement to the programmable control computer for processing; and. the programmable control computer including means responsive to the signals corresponding to the actual movement of the first and second bodies and to the predictive signals for producing a control signal applied to the PTO for adjusting the force between the PTO and the first and second bodies for increasing the average energy extracted from the waves by the WEC. first and second bodies (100,200) which can move relative to each other in response to waves; a power take off device connected between the first and second bodies (100,200) to convert their relative motion into useful energy; a programmable control compute including means for selectively controlling forces between the PTO and the first and second bodies; characterized by: a sensor, external to the WEC, for sensing waves incoming onto the WEC upstream of the WEC and supplying signals corresponding to the incoming waves to the programmable control computer for generating signals predictive of the effect of the incoming waves on the WEC; means responsive to the movement of the first and second bodies (100,200) for generating signals indicative of their actual movement and supplying signals indicative of the actual movement to the programmable control computer for processing; and. the programmable control computer including means responsive to the signals corresponding to the actual movement of the first and second bodies and to the predictive signals for producing a control signal applied to the PTO for adjusting the force between the PTO and the first and second bodies for increasing the average energy extracted from the waves by the WEC. a sensor, external to the WEC, for sensing waves incoming onto the WEC upstream of the WEC and supplying signals corresponding to the incoming waves to the programmable control computer for generating signals predictive of the effect of the incoming waves on the WEC; means responsive to the movement of the first and second bodies (100,200) for generating signals indicative of their actual movement and supplying signals indicative of the actual movement to the programmable control computer for processing; and. the programmable control computer including means responsive to the signals corresponding to the actual movement of the first and second bodies and to the predictive signals for producing a control signal applied to the PTO for adjusting the force between the PTO and the first and second bodies for increasing the average energy extracted from the waves by the WEC.