This work investigates an acoustic fluid structure interaction formulation. It is applied to an immersed steel structure in non-flowing water. The system is discretized using 3D solid continuum and acoustic fluid finite elements. Fluid structure interactions are formulated according to Zienkiewicz’s work for submerged dams. We find that the sensitivity of various approximations and problem parameters are critical to fluid structure finite element problems of this formulation. In conclusion, this formulation is found to be useful as a motion study for sample problems of all scales for which the acoustic motion is to be approximated.