We explain how the motion of a wing paddle through water generates lift pulling the paddle forward-outward thus giving additional forward thrust.
Wing paddles were first used by the Swedish national team in the mid 1980’s for flatwater sprint racing. Within a few years, the times in all Olympic sprint kayak events dropped by about 2% and wing paddles became necessary equipment for anybody hoping to be competitive in flatwater races.
Convex and concave side of a wing paddle.
A Wing Paddle Acts Like a Wing
A wing paddle looks like a spoon and acts like a wing or sail generating lift on the convex side, which pulls the paddle forward-outward at the expense of overcoming drag using your arms to force the paddle through the water backwards. This gives additional forward thrust as compared with a flat paddle with forward thrust mainly from drag.
The lift/drag ratio of a wing varies with the angle of attack aoa and can be ~ 3 at maximal lift at aoa ~ 20 and ~ 3 times bigger for 3 < aoa < 15.
If you now understand how a wing/sail works, you can understand also how a wing paddle works to give a leverage from drag to lift increasing the forward thrust, with experimental input from a movie. We see that the paddle is inclined to the direction of the kajak with lift giving forward-outward thrust, just as a sail gives thrust-heeling when sailing against the wind. It is the outward motion which gives lift contributing to thrust, while the motion of a flat paddle parallel to the direction of the kayak gives thrust only from drag.
The action of a wing paddle with convex side facing forward-down.
The action of the wing paddle is also used in a technique common on the West Coast of Sweden to
propell a dinghy with just one oar mounted at the stern, which is moved sideways-down-up following an eight-loop pattern while twisting the oar to get a suitable angle of attack with forward lift when moving the oar both forward and backward. Compare with the paddle which always is moved backwards in the water and is lifted out of the water in the forward motion.