I've been using and very much enjoying my WindPaddle sail on my Ches 17 for about a year now.  By my estimate, all other things being equal, I spend about 1/6th (60 degrees out of the 360 degree compass) of the time going in a direction the WindPaddle can take me without doing much work paddling, and I'm lazy!  I use a caribiner attached to my chest to hold the "sheet" loop. That seems to work well, and frees up hands for paddling, etc..  The WindPaddle goes up and down so fast (probably 5 seconds) I even use it in winding rivers so long as there is about 100 yards or more downwind (and the wind is greater than 5 kts).

I was out last weekind in winds > 15 kts. with about 1.5 ft waves.  It was getting to be a lot of work and very busy doing course correction strokes, trimming the sail, etc..  For that reason, and because I think I'll be able to get better broad reach angles if I can concentrate more on sail control, I'm considering a rudder.  Also probably won't hurt to aid with weathercocking even without the sail, even though I've never been very bothered just doing occasional corrective strokes without the sail. 

I've never owned a kayak with a rudder, so I'm looking for opinions. Might it be a good idea to go for the bigger "tandem/Sit-on-Top" Smart Track rudder given that the primary reason for the rudder is sailing (even though not using a full-blown sail rig)?  I've really never used any boat of any type in my life that I've felt was "over-ruddered."  I doubt the drag difference is really noticeable at all, so the bigger rudder might mean I can just use smaller angles less frequently than I would need with a smaller rudder, but with the big rudder I will be more assured I do have sufficient rudder when really needed.  That said, no use hanging a big "monstrosity" on the back of the kayak if the smaller rudder will suffice.  Opinions?