A 0.4 m diameter (1:30th scale) horizontal axis marine current turbine (MCT) was tested in a circulating water channel. The turbine
performance and wake characteristics were determined over a range of flow speeds and rotor thrust coefficients. Measurements of the
water surface elevation profiles indicated increasing variation and surface turbulence with increasing flow speeds. Blockage-type effects
(where the measured point velocity was greater than the inflow velocity) occurred around the sides of the rotor for all flow speeds.
Although the effects were exaggerated at model scale, it is expected that reasonable variations in water level and flow velocity could also
occur over a full scale MCT array.