The lift, drag, and inertia coefficients and the first ten harmonics of the lift force have been determined through the use of four smooth, four sand-roughened, and one marine-roughened cylinders. The length-to-diameter ratio of the smooth and sand-roughened cylinders was kept constant (L/D = 2) in order to determine the effect of coherence length on the force coefficients. The Keulegan-Carpenter number ranged from about 1 to 60 and the Reynolds number from about 2500 to 800,000. The results have shown that (i) the smooth cylinder data agree quite well with those presented by Sarpkaya [1, 2] and Rodenbusch and Gutierrez [3]; (ii) the drag and inertia coefficients for rough cylinders (k/D = 1/50) become independent of β (= D2/vT) or of the Reynolds number (Re = UmD/v) for β larger than about 4000; (iii) the rough-cylinder data agree quite well within those reported by Sarpkaya [2] and show that the effect of roughness is indeed very profound; and (iv) the rough-cylinder drag-coefficient data of Rodenbusch and Gutierrez [3] are somewhat larger than those obtained in the present investigation.