When a discrepancy is evident, the bare-hull data give lower values of C R than do the tripped 

 data. On Models 4, 6, 7, and 9 for R L > 0.6 • 10 7 and on Models 3, 5, and 8 for 

 R L > 2 • 10 7 , no separate trends could be discerned between the two sets of C R data. While 

 existence of differences may indicate some defects in the analysis method, it is felt that they 

 are small enough to be ignored when selecting the average values of C R . 



Average values of C R for each model in the absence of significant wavemaking are listed 

 in Table 6. Included are values of C R as defined previously, based on model surface area, 

 and values of C R , based on volume to the two-thirds power, c r vol = D R /l/2p U Q 2 (Volume) 2/3 . 

 Each value was based on the faired curve - dotted line in Figure 13 - obtained from all the 

 data on the appropriate model within the R L range 10 7 < R L < 2 • 10 7 . For Reynolds 

 numbers less than R L = 10 7 , the experimental scatter is too large for the data to be useful. 

 For R L > 2 • 10 7 , wavemaking resistance becomes significant. 



TABLE 6 - VALUES OF RESIDUAL RESISTANCE COEFFICIENTS 











C r' 



10~ 3 



Model 



L E /D 



Cp e 



T 



10 7 <R L 



< 2 • 1 7 



S 



Vol 



4620-1 



0.500 



0.667 



0.750 



0.25 



2.1 



4620-2 



1 .000 



0.667 



1.500 



0.24 



2.0 



4620-3 



1.820 



0.667 



2.730 



0.20 



1.7 



4620-4 



3.000 



0.667 



4.500 



0.20 



1.7 



4620-5 



1.000 



0.850 



1.176 



0.23 



1.9 



4620-6 



1.820 



0.850 



2.141 



0.20 



1.6 



4620-7 



0.500 



0.850 



0.588 



0.28 



2.3 



4620-8 



1.216 



0.823 



1.478 



0.21 



1.7 



4620-9 



1.000 



0.933 



1.072 



0.26 



2.2 



Table 6 shows that the measured values of C R , based on S, for all forebodies ranged 



between 0.00020 and 0.00028. Models 3, 4, and 6 had the minimum C R values of 0.00020, 



indicating no gain or loss in C R when increasing L £ /D from 1.82 to 3.00. For parent Model 



3(L £ /D= 1.82), increasing C p from 0.667 to 0.850 did not change the value of C R . Model 



8 is a flat-faced body with a smaller L P /D (1.216) and a larger C p than Model 3, these 



£* E 



changes caused only a slight increase in the value C R from 0.00020 to 0.00021. 



