A large-eddy simulation of flow in an open channel has been carried out at the moderate Froude number,Fr= 0.66, and Reynolds number.Re= 20,800. A resolution has been used that allowed the simulation to be carried out on a workstation; thus enabling the results obtained to be viewed within an engineering context. The code used treats the free-surface exactly and allows it to freely deform with the underlying turbulence. The turbulent features found in this study are consistent with those found both by experimental observations and direct numerical simulations at lower Reynolds numbers where the free-surface has been treated as a stress free rigid lid.