TABLE 4 

 Comparison of Pitch Amplitudes 



Fin symbols correspond to those listed in the Introduction of this report. 













Amplitude of Pitch 









Wave 

 Length 



feet 



Speed 

 knots 







degrees per foot of wave 



height 







No 



Fin 



Fin 



Fin 



Fin 



Fin 



Fin 



Fin 







Fin 



1 



2 



2s 



Ih 



3 



4 



4A 









0.155 



0.165 



0.16 



0.165 



* 



0.145 



0.18 



0.165 





4.82 



0.32 



0.22 



0.205 



0.25 



* 



0.205 



0.22 



* 



480 



9.64 



0.28 



0.18 



0.175 



0.18 



* 



0.185 



0.185 



0.18 





14.46 



0.23 



0.145 



0.145 



0.165 



* 



0.155 



0.165 



0.165 





19.28 



0.19 



0.12 



0.12 



0.125 



* 



0.115 



0.12 



* 









0.20 



0.195 



0.195 



0.195 



0.205 



0.205 



0.20 



0.20 





4.82 



0.22 



0.20 



0.195 



0.22 



0.21 



0.215 



0.215 



0.21 



600 



9.64 



0.255 



0.205 



0.20 



0.225 



0.215 



0.235 



0.225 



0.22 





14.46 



0.29 



0.195 



0.19 



0.235 



0.24 



0.23 



0.22 



0.225 





19.28 



0.28 



0.17 



0.165 



0.20 



0.21 



0.195 



0.20 



0.205 









0.20 



0.19 



0.18 



* 



* 



0.165 



0.19 



* 





4.82 



0.165 



0.18 



0.165 



* 



* 



0.155 



0.165 



* 



720 



9.64 



0.23 



0.21 



0.205 



* 



* 



0.19 



0.215 



* 





14.46 



0.225 



0.21 



0.205 



* 



* 



0.195 



0.225 



* 





19.28 



0.30 



0.20 



0.19 



* 



* 



0.195 



0.21 



* 



♦Test, 



not run. 



















AVERAGE BENDING MOMENT OF FIN NO. 1 (Figure 14) 



The average bending moment experienced by the fin in waves was determined from 

 experimental strain measurements. The moments shown in Figure 14 are averages of the "up" 

 and "down" values. The moments have also been averaged along the chord. The experimental 

 strain records indicate that the bending moment of the forward flexure was higher than that of 

 the after flexure at ship speeds above approximately 10 knots. This is attributed to the ar- 

 rangement of the bending flexures, the tapered plan of the fin, and the type of distributed 

 loading. 



COMPARATIVE PITCH REDUCTION OF FINS TESTED (Figure 15) 



The amplitudes of the pitch with the various fin configurations tested are shown in 

 Table 4 above. These are compared graphically in Figure 15. A more extensive discussion 



(Text continued on page 27.) 



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