L.S,

I have a bit of a situation where i can’t climb out… I want to calculate the angle of a waterline (planar curve) at a certain distance from the center line. See picture below:

Firstly I made a GH definition (see below), the first component is the waterline. I could, with perp frame component and the curve length component, calculate the angle between the x-axis and the waterline at the end of the waterline.

How can I alter this definition to calculate the angle at the point in the first picture?

Many thanks!

/\ Matthijs