Underwater Sequence; Flow, Stagnation line, and Shedding Rail

General Discussion
1

Here is a sequence of screen shots that I took from “New Emissions of Light and Sound” (the best surf movie I have ever seen).

I think it is interesting to observe the angle of the stagnation line, the flow off of the rail, the engagment of the outside fin at different stages.





2

 

 

 

I like this one because you can imagine the water flowing off of the rail at an angle perpendicular to the stagnation line. You can also imagine the lift created by the fin turning the flow, and how that lift would be changed with changes in toe and cant.





3

What's a stagnation line?

4

http://www.answers.com/topic/stagnation-point

 

It is the point (or line since we surf in 3-d) where the flow is divided by the hull. Some of the water is directed, by the hull, off of one rail, and the rest of the water is directed off of the other rail. The stagnation line is where they split.

 

5

In picture #4 you can see that the stagnation line is inside of the outside fin. Only the tip of the outside fin is in the wave.

6

one of the coolest things I’ve seen is a hinged tail section that, when flexed articulates the tip of the main center fin to accentuate the turning radius given which side of the tail is flexed.

so when I (goofy) lay in to a big backside bottom turn, not only does the hinged tail collapse a bit, tightening my rocker line, but it is also manipulating the center fin to further tighten that arc and provide more drive out of the turn.

kayu: the future of surfing is the “situational” component whose form can be subtly manipulated based on feedback from the rider or the water flow.