- The interactive behavior of closely spaced slender structural members excited by random seaways is quite complex and an accurate predictive model is not yet available. Current design methods yield results which engineers recognize as being imprecise, since they are based upon an incomplete understanding of the physical processes. In this article the results from large scale model tests involving both a single cylinder subject to random seas and a pair closely spaced cylinders under identical conditions are presented and compared. The results presented focus upon the interpretation of probability distributions along the cylinders. Analysis of the displacement and velocity response behavior indicate strongly nonlinear fluid/structure interaction for the paired cylinder configuration.