Experiential Research on the Corrosion of Propeller Blades and Sleeves

Abstract

Researches of various kinds have been made on the causes of corrosion damage on manganese bronze casted propeller blades of ships built after the War, but very few of them attract the practical engineers' attention. The surface of the propeller blade of the A-Maru built at a shipyard in this district was subjected to very severe corrosion, i.e., six months after her first voyage one blade of 2,205 kgs lost 25 kgs of its weight. While the B-Maru which was built at the same shipyard did not suffer such corrosion after the same period of service as the former. The fact that there is such difference between the two cases prompted the author to make a study of this problem the solution of which will present a means of protecting corrosions. Moreover, many corrosion damages have occured on propeller shaft sleeves recently and it also has become a very serious problem. It, however, being very difficult to study the full process of corrosion on sleeve for lack of chances of the inspection of propeller shaft, long-term experience alone will solve this problem. In this paper the author tried to solve it from a view point of a field engineer and could draw a conclusion from the experience of inspecting many ships. This research aims at eliminating the damages of these kinds in order to improve the operating performance of vessels and moreover at contributing to the Japanese mercantile marine and future naval forces. The author hopes heartily that persons who take interest in the problem make comments on this paper.