C band radar images of ocean gravity waves off the Norwegian coast were processed into one-dimensional azimuth spectra. These spectra were used to measure the azimuth spectral (width) cutoff on the basis of a least squares fit to a Gaussian spectral shape. The widths were calculated for a range of wave heights (2--5 m) and wind speeds (2--18 m/s) during 3 days in March, 1988. Velocity smearing (&sgr;v) estimates were extracted, independent of R/V and incidence angle, based on an imaging model and the measured azimuth cutoffs with &sgr;v values varying from 0.4 to 0.7 m/s. Quantitative velocity smearing estimates are important as input to models describing the distortion in wave imagery. We propose a first-order model which neglects velocity bunching for ocean swell with peak wavelengths longer than about 250 m. This model is offered as a first estimate of when ocean wave swell will be detected by the C band SAR on board the ERS 1 spacecraft. The model predicts that this swell will be imaged under light winds of the order of 2--4 m/s. Higher wind speeds cause larger smearing, which may result in significant distortion of the imaged swell provided that the swell is traveling near the direction of the spacecraft ground track. ¿American Geophysical Union 1991