engleski

Comparison of IACS Classification Societies Propeller Strength Calculations

Marine propeller is the essential ship propulsion system component from the functional point of view. It can also become a safety component in case of storm and heavy weather. For this reason all of the world wide recognized marine classification societies acting within the International Association of Classification Societies, IACS (among them Croatian Register of Shipping) prescribe their requirements for minimal propeller blade thickness from strength point of view and the procedure for its calculation in their Classification Rules. Though IACS societies base their calculation procedures for other propulsion system components (e.g. engine crankshaft, marine gears, shafting, etc.) upon common approach prescribed in the IACS Unified Requirements publicly available and developed together by participation of all IACS societies, this does not apply to the propeller strength calculation procedures. Each IACS society has its own approach, though all of them are modelling the same physical phenomenon: ship propeller in water stream. The aim of this paper is to compare the propeller calculation procedures by various IACS calculation societies, focusing on their results validated on a few selected propellers that have been proven in practice. The analysis presents the results in a way that it can be concluded whether a certain society underestimates or overestimates the propeller blade thickness. These results show that calculation procedures of different IACS societies really provide significantly different results for the required thickness of propeller blades, concluding that it will be really important for IACS to put additional effort trying to harmonize these calculations, possibly in a form of an IACS Unified Requirement.

Marine propeller strength ; IACS Classification Societies ; IACS Unified Requirements

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