A mathematical model was developed to analyze the motions of a tower-tanker system. The buoyant tower is assumed to be pivoted at the base and connected to a ship by a mooring arm or hawser (which is treated as a linear spring system) at some elevation above the pivot. The steady and dynamic loads were considered collinear so that the ship assumes a head sea position. The solution was given in a semiclosed form which was computerized by Fortran programing. A wave tank test was performed, with models on a 1:48 scale, to test the validity of the analytic model. These tests showed that the mathematical predictions compared well with a fairly linear system. The correlation was quite good even for a nonlinear spring system as long as the amplitudes of oscillations of the system were small. For large oscillations of a nonlinear spring system, the correlation is not expected to be as good. For a soft spring-mass system, the irregular (or random) waves produced an oscillating drift force on the ship which was not obtained in the present analysis.