operation in calm water. mayeatelag gives a good review of the mechanisms 
and procedures for predicting the effect of the seaway on bearing forces 
which, in principle, also apply to unsteady loading on an individual 
blade. Keil et ata and Watanabe et a a present strain measurements 
on the blades of full-scale propellers in both calm and rough seas. 
Apparently no rational analytical procedures are available for 
accurately calculating the time-average loads per revolution or the un- 
steady loads including variation with blade angular position during crash- 
ahead or crash-astern maneuvers. These loads may depend on many factors 
including the time rate of change of propeller pitch p (for CP propel- 
lers), time rate of change of rotational speed n, time rate of change of 
ship speed V, propeller blade-section stall, cavitation, ventilation, 
flow separation from the hull, and large interactions between the propel- 
ler and the hull. Some of these factors are discussed and considered by 
Hawdon et als? 
For turns, the factors affecting the time-average loads per revolu- 
tion and the unsteady loads are somewhat the same as those affecting the 
loads under crash-ahead and crash-astern conditions except that for turns, 
there is a relatively large drift angle of the flow into the propeller. 
This drift angle tends to increase the circumferential nonuniformity of 
the flow into the propeller, thereby increasing the unsteady loading. 
However, this circumferential nonuniformity of the inflow tends to be off- 
set by the lower values of ship speed and propeller rotational speed in 
turns compared to steady ahead operation. 
Prior to the present R&D investigation, no experimental measurements 
existed to the authors' knowledge which showed the time-average loads and 
aseie, R., "Propulsion Factors and Fluctuating Propeller Loads in 
Waves," Proceedings of the Fourteenth International Towing Tank Confer- 
ence, Report of Seakeeping Committee, Appendix 7, Vol. 4, pp 224-236 
(CLS) 
CAS LLM 
"Keil, H.G. et al, "Stresses in the Blades of a Cargo Ship Propeller," 
Journal of Hydronautics, Vol. 6, No. 1, pp 2-7 (January 1972). 
24 
Watanabe, K. et al, "Propeller Stress Measurements on the Container 
Ship HAKONE MARU," Shipbuilding Research Association of Japan, Vol. 3, No. 
3, pp 41-51 (1973). 
