A systematic Data Quality Checking Protocol for Vessel Mounted Acoustic Doppler Current Profiler observations is proposed. Previous-to-acquisition conditions are considered along with simultaneous ones. Independently of internal systems, location and misalignment, the auxiliary systems to acquisition determine the accuracy range of the current velocity profiles. Simultaneous-to-acquisition navigation conditions provide the physically descriptive weight (or reliability) of significance for each individual current profile. The formulation of the Data Quality Checking Protocol is followed by actual applications and examples from cruises aboard R/V "García del Cid" in the Western Mediterranean Sea.