A Doppler velocity log sonar measures the relative velocity between an instrument and the bottom of a body of water by estimating the Doppler shift of back-scattered sound in multiple beams that point in different directions. The long-term-velocity accuracy of phased-array Doppler velocity logs contains errors including terrain bias, absorption bias, side-lobe coupling, and element spacing error. In this work we show that the theoretically derived long-term accuracy can be achieved in the field under different operating conditions. Distance traveled is measured by integrating the estimated velocity and it is compared to the distance traveled as measured with GPS. Accuracy measurements of Teledyne RDI Pioneer 300 and 600 instruments were performed on the San Diego Bay and the San Vicente Reservoir. The measured accuracy of the two instruments was within the specified accuracy by a large margin.