Since the steady drift force does not depend on the second order potential, the solution can be attained without calculating it, thus reducing enormously the computational burden. The downside of this approach is that if there are significant changes with the frequency in the QTF, as is the case if the body is floating in shallow water, the approximation might be unsatisfactory. In fact, it has been shown [ 9 ] that in some cases Newman’s approximation can underestimate the slowly varying drift forces by around 30%.