There have been proposals for wind turbine and autogiro boats for more than a century. Wind turbine boats typically use a horizontal or vertical axis wind turbine to drive a propeller, which in turn powers the boat, while autogiro boats use thrust forces on rotating vanes directly to power a boat. The promise has always been that one need not know how to sail to operate a wind turbine boat, and can move directly into the wind, and directly downwind faster than the wind speed. While there have been many proposals, instances of practical use of these technologies are few and far between. In fact, the Amateur Yacht Research Society publication AYRS 120-1 (pages 48-64) actually suggests that a horizontal axis wind turbine multihull boat is impractical, and cannot go directly into the wind.
The failure of practical application of wind turbine technology to watercraft may be due to a failure to properly meld existing components into an optimum combination. The failure may also be due to the failure to produce enough effective power for moving the boat due to power transmission losses, incorrect selection of the wind turbine configuration, what to do with the wind turbine when docked, or a combination of these and other factors. In any event, according to one aspect of the present invention, a wind turbine watercraft is constructed that will be operational and can power directly into the wind, and overcomes all of the difficulties mentioned above. However the invention is not limited to a wind turbine watercraft alone, but rather includes as separate and distinct concepts: a collapsible vertical axis wind turbine in general (for use on land as well as with a watercraft); a suitable material and shape for catamaran (or other multihull) hulls of a watercraft; and a power transmitting mechanism with little or no power transmission loss.
According to one aspect of the present invention, there is provided a vertically collapsible vertical axis wind turbine comprising: 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 may be positioned, and the vanes are constructed, so that the wind turbine has an open helix configuration, or a Savonius configuration, or other conventional vertical axis wind turbine configurations.
Preferably the at least one of the vane supports comprises a first vane support mounted to the shaft by a locking device, the locking device removable to allow movement of the first vane support with respect to other vane supports along the shaft. The first vane support may comprise the top vane support. There may be at least three vane supports vertically spaced from each other on the shaft, including a second vane support mounted to the shaft by a removable locking device. The locking device may comprise a locking pin extendable through aligned substantially horizontal openings in the shaft and first (and second) vane support(s).
Each vane support may comprise a hub having a central substantially vertical bore, and a plurality of curved spokes extending generally radially outwardly from the hub and operatively connected to a vane. Preferably, the hub central bore and the shaft have at least one radially extending projection and vertically elongated groove which cooperate to key the vane support to the shaft (for example the at least one radial projection is in the hub central bore and the at least one vertically elongated groove is in the shaft). Each vane support may have four spokes space substantially uniformly around the hub. The spokes of the lowest vane support on the shaft may have a significantly smaller radial dimension than the spokes of a vane support above them, so that the vane is tapered radially inwardly from the above vane support to the lowest vane support.
The vanes may be made of kite or high performance sail material. At least one vane optionally includes at least one substantially vertical or substantially diagonal batten therein.
According to another aspect of the present invention there is provided a multihull watercraft comprising: a plurality of hulls; a propulsion mechanism mounted between two of the hulls; a vertically collapsible vertical axis wind turbine operatively fore mounted to at least one hull, the wind turbine having a shaft; and an operative connection between the wind turbine shaft and the propulsion mechanism. The vertically collapsible vertical axis wind turbine may comprise a Savonius wind turbine or an open helix wind turbine, and may have the details of construction described above. That is the wind turbine may comprise 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 propulsion mechanism may comprise a horizontal propeller and the operative connection between the wind turbine shaft and propeller may comprise a flexible shaft having at least about a 70 degree (e.g. about 90 degree) bend therein. The propeller may have a diameter of between about 10-14 inches, and may be mounted so that during normal loading of the watercraft roughly half of the propeller is in water and roughly half is out of water. Also, at least portions of the hulls which normally engage water may be made of low friction marine grade polyethylene (Roplene®).
According to another aspect of the invention there is provided a watercraft comprising: a watercraft body (e.g., but not necessarily, a multihull); a vertical axis wind turbine having a substantially vertical shaft mounted with respect to the body for rotation with respect to the body; a horizontal propeller mounted to the body for rotation about a generally horizontal axis, and a flexible shaft having at least about a 70 degree (e.g. about 90 degree) bend therein operatively connecting the wind turbine shaft to the horizontal propeller. A clutch may be provided between the wind turbine shaft and the flexible shaft, the clutch positioned above the flexible shaft bend.
The invention, and its various aspects, will be described more fully—but in a non-limiting manner—with respect to the included drawings.