Single waves with high amplitudes, sometimes called rogue, or killer waves, appear surprisingly on the ocean and sea surface. Such waves are very dangerous for ships and for coastal structures due to their destructive high steepness and height. Is there ability to creation of these killer unidirectional waves in laboratory channel, in order to future tests of the ships and the coastal structures ability to withstand the impact, was studied. The spatial Zakharov equation is applied in the present study. Evolution of unidirectional nonlinear wave groups with wide spectra was studied experimentally and numerically. A focusing of an initially wide wave train that is modulated into a single steep wave at a prescribed location along the wave channel was investigated. The experimental study was carried out in two wave channels: a 330 m long Large Wave Channel in Hanover, and an 18 m long Tel-Aviv University wave tank. The study allows concluding that the unidirectional spatial Zakharov equation can serve as an effective computational model for description of evolution along the wave channel of nonlinear wave fields with no limits on their spectral width.