Abstract
Recent days, owing to get better propulsive efficiency the number of propeller revolutions decrease considerably. However, it arises increasing stopping time in crash astern maneuver. Present paper deals with the crash astern performance of CPP (Controllable Pitch Propeller) and FPP (Fixed Pitch Prope11er). The model ship used is SR174B4 (Panamax type bulk carrier) and it has the propeller with large diameter and low rotation. Crash astern performance of SR174B4 equipped with FPP was studied by SR174 committee. Authors carried out the self propulsive tests of SR174B4 with CPP varying propeller loading and got the self propulsion factors. With the factors, and with the quasi-steady treatment, the stopping ability of real ship was estimated. The astern thrust of CPP and FPP alone is about the same. Concerning to required time of stopping, the case equipping a CPP is less than the case equipping a FPP in full load condition, but it reverses in ballasted load condition because of air drawing. It should be remember from the results that the stern draft in ballasted load condition of ships equipped with CPP must keep sufficient to prevent air drawing. The most important factor to affect the stopping ability is the maximum reverse pitch angle in the case of CPP and the maximum number of reverse revolutions in the case of FPP.
