Abstract A model-scale naval surface combatant, DTMB 5512, is studied experimentally in steady forward speed and regular head waves with the Iowa Institute of Hydraulic Research towing-tank facilities. Unsteady resistance, heave force, pitch moment and free-surface elevations are investigated with different measurement systems for a fairly wide range of test conditions. Test data is procured for validation of RANS computational fluid dynamics codes and for understanding the physics of unsteady ship hydrodynamics. In the first part of the two-part paper, details of data reductions, measurement systems and uncertainty assessment procedures are provided.