The marine structures has a staggered array depending on the geographical characteristics of the surroundings. This wake flow occurs in the gap of such a staggered arrangement has a heavy influence on the vessels and structures. Also, Study on fluid flow around simple objects has contributed greatly to solve many engineering problems that occur in a variety of industries such as real fluid machinery, civil engineering, environment and etc. This study has progressed with changing aspect ratio and position of model by using PIV. It shows that speed reduction ratio is increased with the large movement of upper model and 1:2 aspect ratio.