Maneuverability describes a vehicle's ability to change course or turn. Maneuverability of conventional underwater vehicles, such as torpedoes, can be determined by altering the position and length of control fins. To perform large-area surveying tasks, autonomous underwater vehicles (AUV) generally require different maneuverability characteristics in their vertical and horizontal planes of motion. Furthermore, AUV are significantly slower than torpedoes, and control fins are relatively ineffective at slow speeds. While relying solely on control fins to determine the maneuverability, this study investigates the maneuverability characteristics of a flat-streamlined underwater vehicle. A planar motion mechanism (PMM) testing system is adopted to conduct a series of captive model tests in order to measure the stability derivatives of the vehicle, AUV-HM1. Stability and maneuvering indices are then derived from the measured data of stability derivatives. Finally, maneuvering criteria of a flat, baseline vehicle are evaluated using a prediction method.