FOUUNG OF SHIPS' BOTTOMS 



221 



That this is due not so much to the actual effect of cruising as to the fact that such 

 boats are not in harbor sufficiently long to accumulate heavy growths is seen by 

 comparison of this diagram with those given in Figures 25 and 26. 



PERCLNTAGE OF SHIPS IN EACH GROUP 

 10 20 30 40 50 60 70 80 90 100 



TIME ' 



0-3 



IN 



MONTHS 4-7 

 SPENT 



IN 8-n 



CRUISING 



12-15 



LJno Flight H moderate 



FOULING fouling FOULING 



riQ. 27. — Belation between time at sea and amount of fouling 



L HEAVY 

 FOULING 



In Figure 28 is shown a combination of Figures 26 and 27, indicating a more 

 accurate relationship between cruising and fouling. As indicated, this table shows 



PER CENT OF TOTAL NUMBER OF SHIPS IN EACH CLASS. 

 10 20 30 40 50 60 70 80 90 100 



S 5-29 



§ 30-59 



z 



^ 60-79 



^ 80-89 



^ 90-94 



o 95-98 



£ 99-100 





CLEAN 



MODERATELY FOULED 



^^ LIGHTLY FOULED H HEAVILY FOULED 



Fig. 28.— Relation between the amount of fouling and the per cent of total time since last dry docking spent in cruising 



