Old as Dirt!
Join Date: Nov 2008
Location: Tampa Bay Area
Thanked 139 Times in 132 Posts
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Re: End Plate Effect
You may be too young to remember it, but the great debate about Australia II's winged keel, and its performance during the 1983 AC competition involved, in part whether the performance enhancement resulted from the yacht's lowered CG or end plate effect:
The lack of end-plate effect on the top end of rudders where a portion of the rudder extends above the water in old IOR style yachts, can make aeration a serious handling problem. I once proposed installing winglets--similar to Doelfins--on the top of the rudder, with a positive dihedral angle, just below the point where they would have touched the hull with the rudder at its stops, on a boat we raced on in the mid-80's, to prevent aeration but the owner dismissed the idea. "Just watch for bubbles in our wake" he instructed (to warn us of when we were about to loose it and needed to ease the pressure on the yacht). I think it would have worked but...
"It is not so much for its beauty that the sea makes a claim upon men's hearts, as for that subtle something, that quality of air, that emanation from the waves, that so wonderfully renews a weary spirit."