  We report experimental observations of two canonical surface wave patterns
--- ship waves and ring waves --- skewed by sub-surface shear, thus confirming
effects predicted by recent theory. Observed ring waves on a still surface with
sub-surface shear current are strikingly asymmetric, an effect of strongly
anisotropic wave dispersion. Ship waves for motion across a sub--surface
current on a still surface exhibit striking asymmetry about the ship's line of
motion, and large differences in wake angle and transverse wavelength for
upstream vs downstream motion are demonstrated, all of which in good agreement
with theoretical predictions. Neither of these phenomena can occur on a
depth-uniform current. A quantitative comparison of measured vs predicted
average phase shift for a ring wave is grossly mispredicted by no-shear theory,
but in good agreement with predictions for the measured shear current. A clear
difference in wave frequency within the ring wave packet is observed in the
upstream vs downstream direction for all shear flows, while it conforms with
theory for quiescent water for propagation normal to the shear current, as
expected. Peak values of the measured 2-dimensional Fourier spectrum for ship
waves are shown to agree well with the predicted criterion of stationary ship
waves, with the exception of some cases where results are imperfect due to the
limited wave-number resolution, transient effects and/or experimental noise.
  Experiments were performed on controlled shear currents created in two
different ways, with a curved mesh, and beneath a blocked stagnant-surface
flow. Velocity profiles were measured with particle image velocimetry, and
surface waves with a synthetic schlieren method. Our observations lend strong
empirical support to recent predictions that wave forces on vessels and
structures can be greatly affected by shear in estuarine and tidal waters.
