It seems the angles are going to be highly dependent upon technique, and coaching preference (more upright, less ROM, higher cadence vs. more swing, greater ROM, and lower cadence). Good luck

Before the propulsive phase, the angles of the ankle, knee and hip are at maximum flexion in the cycle, ie ~ 70 ° of dorsiflexion to the ankle (0 ° = foot fully extended) ~ 120 ° of flexion in the knee (0 ° = fully extended) and ~ 40 ° of flexion in the hip (Janshen et al. 2009). The angular amplitudes for the knees, ankles and hips during the propulsive phase are approximately of 110 °, 70 ° and 100 ° (Janshen et al. 2009). The extension of the legs is more or less complete depending on the level of the rowers (Hase et al. 2004). See also Soper and Hume 2004 and  Rodriguez et al. 1990.

Mr. Nicolas Alain Turpin Top man you are, Much appreciated. Thanks Much.