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CODOG · 10-23-2007, 07:58 AM

I've not heard of this before. I'd be interested in seeing a photo / link to this.
A 2 knot increase in speed is a bit much to take on trust, my brain tells me the increased diameter of the shaft 'sheath' would if anything add to drag, unless the mechanics of it work because the rotating surface of the shaft is creating more drag originally. Cant see it personally, but would be happy to be proved wrong. Also, I'd be cautious about blocking the water getting into the P / A bracket bearing if indeed one was fitted. Is this 'sheath' around the shaft cylindical or is it shaped, perhaps with an aerofoil section ?

10-23-2007, 07:58 AM	#4
CODOG Senior Member Join Date: Jan 2007 Location: Bournemouth, southern England Posts: 228	I've not heard of this before. I'd be interested in seeing a photo / link to this. A 2 knot increase in speed is a bit much to take on trust, my brain tells me the increased diameter of the shaft 'sheath' would if anything add to drag, unless the mechanics of it work because the rotating surface of the shaft is creating more drag originally. Cant see it personally, but would be happy to be proved wrong. Also, I'd be cautious about blocking the water getting into the P / A bracket bearing if indeed one was fitted. Is this 'sheath' around the shaft cylindical or is it shaped, perhaps with an aerofoil section ?