The performance of a narrow-band passive acoustic tracking system utilizing Doppler frequency shift depends upon both the sensor field geometry and the accuracy with which frequency shifts may be estimated. In general, there exists a relationship between these two factors independent of the implementation of an actual processing system. The characteristics of this relationship are presented in this paper with specific performance bounds being obtained for typical sensor field geometries. It is shown that for frequency estimation accuracies obtainable with currently available hardware, and within the constraints of available signal-to-noise ratio, sensor field geometry becomes the major determinant of tracking performance.