and Rees caution measurements in inclined flow have been made by Albrecht and 
Suinnlies Predinenenilleoe and Raccundl. “ere measurements on partially sub- 
merged propellers have been made by DOBeveas 
Experiments in wakes generated by screens are advantageous for 
evaluating the ability of a procedure to calculate the loading for a given 
wake since for this case, the propeller apparently does not influence the 
wake pattern. Although some good correlation has apparently been obtained 
between analytical predictions and unsteady bearing forces measured be- 
Tak aL 
hind wire grid screens, correlation has been rather inconsistent 
between analytically predicted unsteady blade loads, or resulting 
; S aL 21 
strains, and measured blade loads, or strains. 20 
The mechanism by which the seaway influences the mean and unsteady 
blade loads is complex. Factors include the increased mean propeller 
loading due to increased hull resistance and the increased unsteady load- 
ing resulting from the influence of the free surface and modification of 
the flow pattern into the propeller disk. This flow pattern is influenced 
by (1) direct trochoidal velocities from the ocean waves, (2) relative 
velocities of the propeller due to ship motions, and (3) modification of 
the hull wake pattern due to the seaway and ship motions. Procedures for 
calculating the loads in a seaway are much less refined than for steady 
I esisteeitl. A.E., "Hydrodynamic Propeller Loading in the Behind 
Condition," det Norske Veritas Research Department Report 74-31-M (1974). 
SO MIpreChes K. and K.R. Suhrbier, "Investigation of the Fluctuating 
Blade Forces of a Cavitating Propeller in Oblique Flow," International 
Shipbuilding Progress, Vol. 22, No. 248, pp 132-147 (April 1975). 
gpeduerries R., "Untersuchung uber die Belastungsschwankungen am 
Einzelflugel schrag angestromter Propeller," Schiffbauforschung, Vol. 8, 
No. 1/2, pp 57-80 (1969). 
abana G.F., "Time-Dependent Blade-Load Measurements on a Screw- 
Propeller," Presented to the Sixteenth American Towing Tank Conference, 
Instituto De Pesquisas Techologicas, Marinha Do Brasil (August 1971). 
eT er elldenet R., “Last Remarks on the Comparative Model Tests on 
Vibratory Propeller Forces," Proceedings of the Fourteenth International 
Towing Tank Conference, Report of the Propeller Committee, Appendix 7, 
Vol. 3, pp 421-426 (1975). 
