Compute the retarding force of water on the ship, based on a drag law
\((1/2)*rho*Cs*A*vs^2\)
where rho is water density taken to be 1024 (kg/m^3), Cs is drag coefficient
stored in parms and A is area, also stored in parms, and vs` is
the ship speed (m/s).
shipWaterForce(vs, parms)Ship speed in m/s. (Consider using knot2mps() if you
prefer to think of speeds in knots.)
A named list holding model parameters, created by
parameters().
Water drag force (N).