  We generalize the Zermelo navigation problem and its solution on Riemannian
manifolds $(M, h)$ admitting a space dependence of a ship's own speed
$|u(x)|_h\leq1$ in the presence of a perturbation $W$ determined by a mild
velocity vector field $|W(x)|_h<|u(x)|_h$, with application of Finsler metric
of Randers type.
