We report on an efficient high-power, widely tunable femtosecond optical parametric oscillator in BiB3O6, synchronously pumped by a frequency-doubled mode-locked Yb:KGW laser at 515 nm. Using collinear type I (o→e+e) phase matching, a resonant wavelength range of 688-1057 nm at a 151-MHz repetition rate is demonstrated, with a tunable idler range of 1150-1900 nm. The output power at 705 nm is 1.09 W for 3.6 W pump power exceeding 30% conversion efficiency. Near-transform-limited pulses down to 71 fs are achieved by deploying extracavity dispersion compensation in a pair of SF6 prisms.