Many of the known wave-powered devices (“WPDs”) comprise (1) a float, (2) a swimmer, and (3) a tether connecting the float and the swimmer. The swimmer generates thrust as the float moves up and down due to surface waves. A WPD is provided with a rigid tether that can be moved from (a) a first position (“adjacent position”) in which at least a part of the tether is adjacent to the float to (b) a second position (“extended position”) in which the tether (i) is extended below the float and (ii) is at least in part substantially rigid. The WPD can if desired be transported, stored, or launched while the tether is in the adjacent position, and the tether can be moved into the extended position after the device has been launched and remain in the extended position while the device is being operated.