[MHml] Cat Rudders Toed In?

[Roy Mills]

At 09:14 AM 9/1/06, you wrote:
>List Friends,
>     Our new to us 35' Cat (designer unknown) appears to have both 
> rudders toed in about half a degree from parallel.  Is this a 
> normal thing with cats or a builder's mistake?  My experience is 
> with trimarans and I would think they should be parallel with the 
> centerline of the hulls.  The rudders are a tapered NACA 0012 foil 
> with the shaft at 25% of the chord.  I'm reattaching the tiller 
> crossbar at the ends of the tillers, and it is 1 1/2" shorter 
> (center of tiller hole to hole) than the rudder shafts are (14' 
> center to center)  The tillers are 58" long.
>Thanks for any advise!,  John Matthiesen, Sugaree Too

         The rudders should be parallel to each other, the tillers 
should be angled in towards each other to provide Ackerman angles to 
the rudders when the cat is being tacked, one hull describing a 
different radius of turn than the other one and thus requiring a 
slightly different AOA to the water it is passing through.

         Roy Mills.

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