number of attachment points 22 positioned about its length at each of these attachment points is a parachute 26 each parachute 26 has an open end 28 and a closed end 30 and a number of lines 24 extending from the parachute towards the open end 28 the lines 24 attach to the rope 20 and transfer force generated by the parachute 26 to the rope 20 the lines 24 also ensure that the parachute 26 remains open when the open end 28 faces the current and closed when the closed end 30 faces the current as can be appreciated by those skilled in the art as the rope 20 is pulled taut by the current 34 working on the parachutes 26 the rope 20 tends to stretch the rope 20 is stretched by the force differential acting along the length the rope 20 experiences a maximum tension t max at the guide wheels 16 as the rope enters the water 32 and a minimum tension t 0 as the rope leaves the water 32 near the pulley 8 as viewed in fig2 the rope 20 travels in a counterclockwise direction during operation although the device 10 may be configured to operate in the opposing direction each rotor 18 reduces the amount of tension in the rope 20 as energy is extracted for example as the rope 20 passes rotor 18 a the tension drops from t max to t a the tension differential across the rotor 18 a can be expressed as t a u2212 t max the u201c loss u201d of tension is caused by energy being transferred to the rotor 18 a as the rope 20 passes the other rotors 18 b j the tension drops steadily to.