: That’ll work fine, but might it not be even simpler using an off
: the shelf gas pedal rudder with the addition of a fixed bungee
: on the front of each.
: With the same adjustment, that would self centre but has the
: addition of having a varied spring response. (And I still think
: a detent would be helpful to the setup).
: In both cases, though not shown, you’ll have to fix the lines to
: the tiller pulley so that no slip happens (because things slip,
: that’s why a detent may also be helpful, heh heh).

Yes, a pedal set with bungees would work just as fine. But a piece of plywood with a slot in the middle is also quite simple ;-)
And I liked the way the pedal parts bent when pressed, conforming comfortably to the foot.
But there are of course problems – I ended up with a little less flex than I would have liked, to avoid the top part twisting under pressure. It is OK on the sea racer, with its directional stability – but when tried on a surfski (Nordic Kayaks Fusion, and a carbon fiber version of the pedal), where the rudder is more vital to control, it was eventually replaced with a standard pedal set.

: I didn’t mean to apply that comment for the foil section view
: (that probably should have a blunt/angled edge to stop variable
: vortex shedding) but for the side view of the blade.
: If you look at Willn’s last post, you’ll see the area just
: above the retract line is rounded. If you shape cut your your
: blade at this location there is a slim possibility that under
: slight angles the blade would still ‘carve’ its way back in
: (– but nitpicking details).

I agree, some work there will be beneficial. But the comment on turbulence concerned the rounding of the hole in the rudder housing that I believe one of Willn's drawings showed (if I did not misunderstood that ;-). If the transition between the cylinder part and the blade part of the housing was a soft rounded curve, the rudder would slide in nicely even at angles – but the holes would create turbulence