DK 9" high chord rudder. $50 shipped to USA.

Pretty much new DK rudder (Donald Kiesling here). Just didn't work on my ski. The shaft size and square yoke insert is for a Fenn (or equal. The shaft length is 5 & 5/8 to the yoke insert. The yoke cutout is 3/32 and the overall length of the shaft including the threads is 6 & 1/16. (Sorry, all measurements are in inches since thats the tape measure I have around lol.) I sanded about 1-2mm from part of the base to get a perfect fit on my ski, but if I didn't say anything it would be difficult to tell. Shaft is at 90º to the base of the rudder.

$50 shipped in the USA. (Will check out international shipping costs, but its likely to be very high since I'm in Hawaii.)

Will get some pictures up asap.

Someone should grab this.. I absolutely love this rudder on my Stellar SR.

Curious, why didn't it work out?

Bill

Ya, its a beautiful rudder. The reality is that I'm not sure why it didn't work out. It just was more vague and stalled. It did also make the ski feel a little more stable though.

The ski is 6.6m with little rocker, so my gut feeling is that the large foil along with the thinner width didn't exert enough force before it would stall. Its sort of like turning a long thin wing abruptly vs a short wide wing. The thin one will stall and slide through the air while the shorter wider wing will pivot.

My guess is that if you have a ski with more recent rocker, the increased predictability and reduced force required by this rudder by way of its foil and height vs. width has to be amazing.

Again, my guess is that this boat needs a rudder to be very wide and with little foil to really "bite" the water and exert a lot of force solely by virtue of the angle of attack and not by flowing around the rudder, somewhat similar to the difference in a supersonic airplane wing vs. a regular wing. (I'm not a Naval engineer, so I realize this description probably only makes sense to me lol.)

Odd, I use one on a Stellar SEL sometimes and it's anything but vague and is very aggressive and powerful. Does your rudder have a lot of sweep like a weedless?

Its a 20 degree leading edge.

Its things like this that remind me that fluid dynamics is extremely complicated Honestly I have no good explanation for it, wish I did.

Purchased two of Don's rudders at end of our downwind season, paddled only once downwind in mixed conditions under twenty knots however noticeably more precise than the Stellar SEI 9" surf rudder. Have used both large and small (normal) rudders with no issues other than weed on the big (long straight) one.

Without question the DK rudder turns better on the flat and at medium speeds though no big runs yet to potentially stall on.