312 



Test 96 

 Meas. Time : 

 tm =5.955ec 

 P =/,3N/cm3 



n =101.2 RPM 

 Vs =21.2 kn 



Test 97 

 Meas. Time : 

 tm = 6.5 sec 

 go =39N/cm2 



n = 101.2RPM 

 Vc, = 21.il<n 



100 /xm 

 ■ Diameter 



20 40 60 80 

 5-12-1977 Wind Force.- i Beautort 

 FIGURE 20. Nuclei distribution for calm water. 



with the pitching ship but still within the narrow 

 range of So = 39 up to Z^a = 62 N/cm'. Considering 

 the Tests 47 to 65 (Figures 15 to 17) and the Tests 

 93 to 97 (Figures 18 and 19) it can be said that in 

 a seaway the nuclei concentration So is higher than 

 in smooth water, and further, that the influence of 

 shipmotions on the concentration Co superimpose on 

 the influence of Vne seaway. 



The measurement series carried out with the 

 Tests 90 and 92 (Figure 20) under ideal weather 

 conditions, show on one hand the good repetitive 

 accuracy of the results for a constant speed in 

 good weather. In this case the number of nuclei 

 per cm^ amounts to So = 18, 19, and 18 N/cm^ at 

 constant measuring periods of 13.6, 13.2, and 13.9 

 for 2000 nuclei. This, however, shows - on the 

 other hand - a clearly lower concentration. So, 

 than with the Tests 61 and 65 in a seaway (Figures 

 17 and 16) . 



Test 70 

 Measuring Time: 

 tm = 13.55sec 

 5o = 18N/cm3 



n =101.7 RPM 



Test 77 

 Meas. Time : 

 tnn =11 5 sec 

 go=27N/cm3 



n =82.9RPM 

 V=; =17.1kn 



Test 79 

 Meas. Time; 

 tm = 3.3sec 

 £o=137N/cm3 



n =59.2RPM 

 = 11.9kn 



80 100 /im 

 — -Diameter 

 4-12-1977, Draft aft DQ = 9-37m; Draft forw. Df =8.08m 



FIGURE 22. Nuclei distributions for different ship 

 speeds . 



A further difference, previously mentioned, has 

 to be noticed when comparing measurements in a 

 seaway and in calm weather. Whilst with typical 

 spectra in a seaway (Tests 61 and 65) the absolute 

 maximum is between the nuclei sizes 30 and 40 ym, 

 it can be detected for calm weather in the smallest 

 measured nuclei range . This phenomenon will be 

 described later (in Section 7) . The measuring 

 series of different speeds for two drafts are 



|cm3 

 1.0 



0.1- 



o.oH 



0.001 

 1.0- 

 0.1- 



aoi- 



0.00V 



1.0- 



0.1 



0.01 



0.001 



I 



lr-L_L_n 



Test 90 

 Measuring Time : 

 tm = 13.6 sec 

 go=18 N/cm^ 



n =100.8RPM 

 TlVs=21.6kn 



\rx. 



n, 



"M 



Test 91 

 Meas. Time ; 

 tm= 13.2 sec 

 £o= 19N/cm3 



n =101.3RPM 

 Vs=21.6kn 



Test 92 

 Meas. Time : 

 tm = 13-9 sec 

 5o = 18N/cm3 



J U T_r~^ 1— n n =101.3RPM 

 Vs=21.6kn 



40 60 



80 



100 120 /""i 

 —f Diameter 



FIGURE 21 

 speeds. 



20 

 4-12-1977 



Nuclei distributions for different ship 



o.r 



0.0V 



aooi 



Test 90 

 Meas. Time : 

 tm =13.6 sec 

 go = 18N/cm3 



n =100.8RPM 

 =21.6 kn 



J ^ 



M 



Test 83 

 Meas. Time : 



go = 140N/cm3 

 n =61.3RPM 



20 40 60 80 100 /u.m 



— " Diameter 

 4-12-1977; Draf oft Da=9.75mj Draft forw.Df = 7-82m 



FIGURE 23. Nuclei distributions on deep water. 



