Affiliations: [a] Lips Propeller Works Ltd., Drunen
Note: [*] Consultant Engineer. At present with Makina ve Kimya Endilstrisi Kurumu (State Mechanical and Chemical Industries), Kirrikale, Turkey, on United Nations Development Programme.
Abstract: In general, efficient running of ships has not yet arrived at the state of affairs as exists in airline transportation, but in an increasing number of cases, there is a directed attempt of cost concious owners to maintain ships at optimum running conditions. Efficient running of main and auxiliary machinery, and maintaining the hull in a state of cleanliness, is applied in general. However, maintaining the efficiency of the propeller has come under scrutiny only since recent time. It is true, and especially in Germany, that propeller efficiency as a function of its condition has been studied for some decades already. But the practical experience of specialist propeller manufacturers has induced them to establish a reconditioning and maintenance service to keep with the need for dependable and efficient use of the propeller. No macroscopic changes in form and spacing occurring, it is only the increasing roughness of the propeller which causes decreasing efficiency in service. Parameters influencing the character of the surface are summarized; and in this respect it is recommended to study actual surface characteristics as in production engineering of high class gears. Additionally, one might introduce the definition of permissible undulation of a surface, as used in gear technology. In the case of propeller manufacture, this is of prime importance to limit, or even to exclude, the possibility of cavitation due to discreet jumps in the location of the centre of curvature of the blade surface.
