Experiment

Towing-tank experiments of coupled pitch and heave motions are presented for a surface combatant advancing in regular headwaves.  The data includes ballasting parameters, encounter frequency, time histories, Fourier series amplitudes, and pitch and heave transfer functions and phase. The geometry of interest is DTMB model 5512, a 1:46.6 scale, 3.048 m long, fiber reinforced Plexiglas hull. Model 5512 is a geosim of DTMB model 5415, a 1:24.8 scale 5.72 m model. The model is unappended, i.e., not equipped with bilge keels, shafts, struts, propellers, or rudders.  The experiments are performed in a 3 x 3 x 100 m towing tank equipped with a plunger-type wavemaker.  The test program is undertaken to create a validation dataset for unsteady Reynolds-averaged Navier Stokes simulations including rigorous and comprehensive uncertainty assessment of the experimental results following standard procedures.  Results indicate that the regular headwaves are in the linear regime except for a few high-steepness cases.  Pitch and heave responses are mostly independent of wave steepness, however, some nonlinear responses are identified mainly for high-speed, short-wavelength test cases.