I agree with Ryan that mostly you need the right structure to klop - trees, reets, snotterbel, hycinth, etc. Usually also better to klop early day or aftrenoon. However, at Bloemhof we often get the barbel in open water or shallow bays and klopping. In Vaal Dam I have caught barbel in deeep open water - swimming in schools on the surface. I dipped for them very successfully with roepstok. Percentage I catch more barble on my roepstok than cranking. But this will differ from individual. In North Gauteng we use the roepstok more than most other provinces. Roepstok is something you need to use with confidence.