The forces that apply to our board modify its balance around the Yaw , pitch and Roll axes.
The Roll axis is parallel to the relative flow and passes through the center of weight application, the inclination of the board is done around this axis of roll.
The Pitch axis is perpendicular to the Roll axis, it passes through the center of weight application, the planing attack angle of the board is around the Pitch axis..
The Yaw axis is perpendicular to the relative flow and to the pitch axis it passes through the center of support. The drift angle of the board is given around the yaw axis.
All the hydrodynamic forces are expressed in this orthogonal reference.
The angle of drift around the yaw axis, the angle of incidence around the pitch axis , and the inclination around the Roll axis describe the attitude of the board in the dynamic mark.
The origin of this dynamic reference is the global center of lift, which corresponds, when the surfer is in stable equilibrium, to the center of weight application. The surfer controls his board and moves his center of weight application to generate rotational moments around these axes. The dynamics of the board is resolved by calculating the moments around these axes: the sum of the moments generates a rotational impulse which makes it possible to define the movement between two points of trajectory.
We will avoid confusing turn and yaw rotation! see surf turn