Abstract
There has been a remarkable increase lately in the number of VLCC (Very Large Crude Carriers) and high speed large container ships, and the high powers involved for propulsion have brought about renewed interest in the improvement of propeller design and manufacture. Two of the most important considerations in this respect will be discussed below:
(1) The corrosion fatigue strength of propellers has to be further clarified and established to allow a more rational approach in determining the optimum blade thickness, light in weight but with sufficient resistance to fracture and breakage. (2) The cavitation erosion resistance has to be improved by selecting the proper material as it appears difficult to solve this problem with the present design method. With this in mind following investigations have been carried out:
(1) The relations between corrosion fatigue strength and thickness of castings have been accurately established through tests carried out with specimens taken from variously sized castings and propellers.
(2) A new method of “Weld Surfacing” using material of superior cavitation erosion resistance has been developed. This method has been applied to actual propellers and good results have been obtained in service.
