Posted by: carldelo on Sep-20-12 5:15 PM (EST)
The function of the ridge is to anchor the stagnation line on the paddle face, or at least keep it from wandering too far. Flutter can be interpreted as oscillation of the stagnation line, causing flow to preferentially spill over one side of the blade, then the other, in rapid succession. The resulting pressure fluctuations on the blade cause the paddle to wobble side to side.
A GP held in a canted manner will generally present enough asymmetry to the flow to anchor the stagnation line in the right place, so a canted GP shouldn't flutter, unless pulled way too hard. An Aleut paddle can be used with the smooth face as the power face in the same way.