Abstract: A vertically collapsible vertical axis wind turbine may be used on land, or on a watercraft (e.g. a multihull such as a catamaran). The turbine may include a substantially vertical shaft; at least two vane supports mounted by the shaft; and at least two vertically collapsible material vanes supported by the vane supports, so that the vanes are movable from a first operative position in which the vane material is substantially taut, to a second inoperative position in which the vane material collapses. The vane supports are positioned, and the vanes are constructed, so that the wind turbine preferably has a Savonius or an open helix configuration. When used on multihull watercraft a propulsion mechanism is mounted between two of the hulls, and there is an operative connection between the wind turbine shaft and the propulsion mechanism. The operative connection may be a flexible shaft having at least about a 70 (e.g. about 90) degree bend therein.