Full-scale marine current energy converter devices have now been operational for several years. These devices have the potential to provide large scale electricity generation when placed in farms/arrays in areas of fast flowing tidal currents. Now the full-scale concept has been proven experienced operators are in a position to provide array developers with devices for such applications, thus at present the first tidal arrays are in the planning and consenting stage around the globe. The inter-device spacing within these arrays can have a profound effect both on the flow field through the array itself and the on the surrounding environment. This paper describes a set of scale experiments aimed at investigating the interaction of devices within an array and potentially highlight some of the pitfalls of future array design which may result in sub-optimal device operation. Experimental results presented herein indicate that particular spacing can lead to regions of accelerated flow which may be exploited to provide greater power production. Further examination of this accelerated flow region is presented, with discourse surrounding the potential issues of placing devices in this region, and impacts the on array geometries as a whole are discussed.