A standard boat propeller, turned end for end, will provide more efficient capture of water energy than a propeller mounted conventionally. The idea here is to load the propeller blades on the same face, or side of the blades. When using the propeller to move the boat, the loaded blades are on the aft end of the propeller axis, the smallest bore end for a tapered shaft. To maximize power produced from a propeller being used as a turbine it should be turned around, with the small bore facing into the flow.
A Kort nozzle, and inlet guide vanes can significantly increase the efficiency of this setup. As mentioned previously, if you can tow a generator pod, efficiency can be much better as there are less disturbance from the hull form.
Under ideal conditions a common boat propeller, mounted backwards, with inlet nozzle and guide vanes, can achieve efficiencies ranging in the 70-80% regime when used as a water turbine. Ideally this should be a 3 or 4 blade prop, with a high fraction of blade area (not a skinny two blade prop). Mounting on the stern shaft of a typical sailboat would be much less efficient, however significantly better than mounting in the normal propulsion direction.
--- In electricboats@yahoogroups.com, Michael Mccomb <mccomb.michael@...> wrote:
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> does anyone have any info on where or how to get one hands on a propeller maximized for regeneration rather than thrust.... i'd gladly give up some thrust efficiency for maximized regen.... any advice gladly received
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