Abstract: A wave energy conversion system has a float and a power generation drum with a drum housing rotationally attached to the float by a shaft attachment. The shaft attachment allows a rotational movement of the drum housing and the float relative to each other. The drum housing holds a cable reel with a cable having a first end part connected to the cable reel and a second end part, where the cable reel is an integral part of or connected to the drum housing to rotate with the drum housing. The float can be positioned in the sea by having the second end part of the cable attached to a submerged structure or to the sea bed. When the float is positioned in the sea, the float may be moved by the waves, which movements cause a rotational movement of the drum housing with electric power being generated.