The expectation would be of wavy lines, as the drawing is trying to depict the tension a person feels when water skiing.
Explanation:
Drawings are a good way of depicting emotions by showing a scene and the form that the artist uses to show a commonplace scene often reveals the theme.
The elements of this drawing which are boat, the person and the waves which can be used for any regular scene on skiing.
So the painting requires to show how it actually feels while skiing and where the tension actually comes from while skiing
For this purpose wavy lines represent the movement of the ski perfectly and thus they can be used to great effect.