Alex wrote; (SNIP) >If you are referring to the balanced rudder fitted later versus >the original rudder fitted to a Klepper, then it is nothing to >do with the balance. Replacing the "barn-door" of a blade >with a long narrow blade makes an enormous difference to >the rudder performance - I know, I've done it. To elaborate on Alex's comments. The reason for deeper rudders (all else being equal) being more functional lies in their being below the separated flow at the stern. At the stern and sometimes even further forward on some boats the flow may be moving in the same direction as the boat. This, of course, is the flow one benefits from when wake riding and if you can hold you bow right up close to the stern you get a nifty free ride. In my much stupider youth I once tried to ride the wake of a barge tow. Great fun but great stupidity. We were sucked along so fast we actually made headway directly into the wind with the sails luffing. All went well until we realised we were being drawn ever closer to the stern of the barge. Talk about panic. Just barely escaped. I was still shaking when we finished the race. An interesting phenomenon can sometimes occur when the boat can actually turn in the opposite direction to that intended because of this reversed flow. I experienced this once when sailing an owner designed IOR rule beater with an oddly shaped stern. Very scary business with the spinnaker up. It was the last boat he designed for himself. ;-) As an aside, you may recall Nick's comments on the Inuit kayak speeds. If you have ever tucked yourself in behind a larger sailboat and been sucked right along you will appreciate the effect on a smaller boat. It is quite an easy thing for a small light boat to keep up with a larger ship so long as one stays in the proper area of the wake. It pays not to accept conclusions from observations until one knows all of the circumstances. But I digress. Of course, rudders, and especially high aspect ratio rudders, work even better when properly shaped. The proper section shape has even greater importance when the rudder is surface piercing because there is no end plate effect and the aspect ratio suffers. The rudder also will have a greater tendency towards ventilation. (SNIP) >The crucial point. I fitted one of my standard Data General >front panel blades (not one of my commercial production >blades). Not sure what this rudder looks like and would be interested in a description of it. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************Received on Tue Nov 17 1998 - 04:41:51 PST
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