You as C/E are requested to inform your company with respect to inspection of propeller in drydock during which you noticed a surface crack on one of the blades. State the steps taken by you as C/E for successful handling of the situation. Also if some surface cracks are noticed on the keyway of a tail shaft, state the steps taken by you for tackling the problem. Explain the effects in case the cracks, as stated are not dealt with at the proper time?
Surface cracks have been noticed on one of the propeller blades:- As soon as a crack has been observed on the propeller blade, the head office as well as the Classification Society must be notified. The services of a propeller expert would also be needed in certain cases. Cracks on a propeller surface may be due to:- Physical damage Faults during casting Physical Damage:- These types of cracks generally occur on the tips and the leading edge of the propeller. Pitting may occur near the tips on the driving face and on the whole of the fore side due to cavitation. Propeller blades are sometimes damaged by floating debris which is drawn into the propeller stream. Such damage must be made good as it reduces the propeller efficiency, while the performance is improved by polishing the blade surface. If a built propeller is fitted, it is necessary to ensure that the blades are tight and the pitch should be checked at the same...