Re-Working Scout's Yuloh 

Moving Scout
Alternating between Yuloh and Stand-up Paddleboard Paddle. 

When my friend John built the yuloh for Scout for me....we were both scratching our heads when we read the plans as to which way the yuloh was to be curved. There is a 30 mm curve built into the loom of the yuloh. The blade of the yuloh is not symetrical. Not even close. There is an "up" side, and a "down" side.  After a lot of discussion we both settled on thinking that the flat side of the blade should be the "Down" side and curved the yuloh accordingly.  Guess what.  LOL  We both got it wrong. After reading everything I can find on the Yuloh and similar propulsion devices, I can see now that we got it backwards. I have been using the Yuloh as is and am able to consistently propel Scout forward at about 1.75 knots.  I am hoping that if I make the correction to the blade I can bump that to over 2 knots sustained. Flipping it over will allow it to make lift in the direction I want to propel the boat.  This will be an interesting experiment to see what change if any it makes. I have yuloh'ed Scout a lot by now, so I should be able to see any change pretty readily. I also put a more abrupt curve in the loom and the entire curve is located above the pivot point so that it should help to automatically rotate the blade and set the leading edge in the downward position on both directions of strokes. 

After a lot of different ideas, I settled on making relief cuts into the loom and installing wedges to reverse the curve. The was far easier than completely re-shaping the blade which is a fairly complex shape. So far so good. I should have it ready to try in the next day or so. 

relief and expansion cuts made...teak wedges ready to be epoxied in

Epoxying in Teak wedges

Showing the new curve

Wedges epoxied in and sanded down

another view of wedges


Now I will add wedges in the other side to stabilize the new curvature...then wrap the whole section in fiber glass tape to re-enforce the area.

More to come.....