FOULING OF SHIPS' BOTTOMS 



227 



waters, as at Beaufort and Norfolk, than in the cooler and more northern waters, 

 as at New York and especially Boston. 



It' will also be noted that the barnacles and some of the others have a more 

 extended breeding period in warm waters than in those north of New York, where 

 these periods are limited sharply for most organisms. It is apparent, however, that 

 for the barnacles and the more serious types of fouling, measures employed to prevent 

 their attachments should be most effective during the early summer months, varying 

 the date according to the latitude of the locality. 



The above data are admittedly not accurate in every detail but serve to indicate 

 the significance of such studies. A more comprehensive study of this problem has been 

 begun by the author, and preliminary results are appended as a preliminary report 

 on seasonal fouling, as determined from panels submerged in various ports by naval 

 vessels. 



Early in the course of this investigation it was realized that accurate data for determining the 

 periods of active fouling could not be gathered by a study of ships' bottoms alone, and it was 

 accordingly recommended that such information for various harbors be ascertained by submerging 

 panels from vessels visiting such ports. In conformity with these plans, 10 sets of panels were 

 prepared by the Navy Department (New York and Norfolk yards), and these were issued to as 

 many ships with instructions to submerge a set of two panels in each port visited, provided the 

 vessel remained there three days or longer. 



Of these panels only three sets have as yet been received for biological study. Of these one set 

 had but three boards and showed no results. The third set received was likewise small and com- 

 pletely dried out when received so that results were difficult to evaluate. The second set, however, 

 showed definite and significant results. These panels had been submerged by the U. S. S. Sirius 

 and represent fouling conditions for limited periods at the San Diego, Mare Island, Bremerton, 

 and New York Navy Yards. The data are tabulated in Table 5. By referring to this table it 

 can be seen that fouling is severe at Mare Island in October, while it is very slight during June. 

 At San Diego growths attach in moderate numbers in June and July, while no fouling, apparently, 

 occurs during November. These data would indicate that at Bremerton, Wash., fouling is moder- 

 ate in late June, while at the New York yard none occurs during late September. It is inter- 

 esting that all of the above data substantiate general conclusions drawn from examination of ships' 

 bottoms. 



Table 5. — Results obtained, with reference to seasonal fouling, from panels submerged by the "Sirius" 



Type of fouling 



Slimy scum; few barnacles. 

 Few barnacles and hydroids. 

 Do. 



Single hydroid. 

 Few hydroids. 

 Scum only. 

 15 minute barnacles. 

 25 barnacles on panel. 

 125 barnacles on panel. 

 Few minute barnacles. 

 Barnacles and few hydroids. 

 A single hydroid. 

 Clean. 

 Slime only. 

 Do. 



500 minute barnacles. 

 25 barnacles and few minute hydroids. 

 1,000 minute barnacles and few hy- 

 droids. 

 Clean. 



Do. 



Do. 



Panel 

 No. 



Date of 

 submer- 

 sion 



Date 

 when re- 

 moved 



Place of submersion 



Depth 

 sub- 

 merged 



Current and condition 

 of water 



19.... 

 20. 



21. 



May 31 

 ...do.... 

 ...do.... 



June 10 



..do.... 



..do.... 



June 23 



..do.... 



..do.... 



July 23 

 ...do.... 



..do.... 



Sept. 16 

 ...do.... 

 ...do.... 



Oct. 21 

 ...do..-. 

 ...do.... 



Nov. 22 

 ...do.-.. 

 ...do.... 



June 5 

 ...do.... 

 ...do.... 

 June 18 

 ...do.... 

 ...do.... 

 July 11 

 ...do.... 

 ...do.... 

 July 28 

 ...do.... 

 ...do.... 

 Sept. 23 

 ...do.... 

 ...do.... 

 Oct. 30 

 ...do.... 

 ...do.... 



Nov. 28 

 ...do.... 

 ...do.... 



San Diego 



do 



do 



Mare Island 



do 



do 



Bremerton 



San Diego 



New York Navy Yard 



do 



do 



Mare Island 



do 



do 



San Diego 



do 



do-.._ 



Feet 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 

 16 



Sluggish, fairly clear. 



do 



. do- 



Fair current, very dirty. 



""do;"" " 



Sluggish, clear 



"""do. 



Sluggish, very clear. 



do 



.do. 



No current, very dirty. 

 "".do'.'" 



Fair current, dirty. 



do... 



do 



Sluggish, fairly clear. 



do 



do 



