This paper outlines the procedures and preliminary results for a set of experiments on the Transverse Horizontal Axis Water Turbine (THAWT), which is a variant of a Darrieus turbine. Testing of a 1/20th scale device was conducted in the combined wind, wave and current tank at Newcastle University. Flow depth and velocity were varied over a range of realistic Froude numbers for tidal streams. Various configurations of the device were tested to assess the merits of the THAWT design. Variants included a parallel bladed device, a “truss” device and a parallel bladed device configured with blades pitched relative to the pitch circle tangent. Experiments were carried out using a speed controlled motor, allowing quasi-steady results to be taken over a range of tip speed ratios. Preliminary results demonstrate that, over a range of flow conditions, the device is capable of exceeding the Lanchester-Betz limit for kinetic efficiency. This is principally due to the relatively high blockage ratio which can be achieved with such a device.