There might be an error in the terminal velocity generated by this simulation. Using the equation of motion we can describe the ulitmate speed of the skier, the speed at which the acceleration equals zero:

Fs - Ff = Fd

where

Fs = W*sin(theta), Ff=mu*Fn=mu*W*cos(theta) and Fd=(Cd*A*p*v^2)/2

hence

sin(theta) - mu*cos(theta)=(Cd*A*p*v^2)/2*W

By using the initial values of the simulation (theta=20, mu=0.1, W=60 and Cd*A*p=0.84), and solving the equation for v, we find that vmax = 19.4 m/s (53.9 km/h) where the simulation predicts 63.8 km/h.