6, In svmnaary, it may "be said that at present there is only one 

 sure method of determing in advance whether the timher structures in 

 a given harhor may he attacked hy destructive horers; this method is to 

 expose test hoards and to examine them monthly with great care. Thus the 

 test hoard is a kind of radar system, warning us (a) when horer attack 

 is imminent, or (h) when horer attack is increasing or diminishing. In 

 addition, it presents a sampling of the fouling organisms present. A 

 continuous program of study. Involving the use of successive panels of 

 test hoards, heccm^s a form of insurance against heavy losses in marine 

 structures. 



A1.08 Method of Operating Standard Test Boards 



The following description of standard test hoards, and the 

 succeeding specifications, paragraph AI.09, were furnished hy the W. F. 

 Clapp Lahoratories . 



1. A standard test hoard consists of a set of nine hlocks or 

 panels spaced two inches apaxt and holted, screwed, or otherwise secured 

 to a 2-in. supporting hack strip of wood or to a metal har (Figure 12) . 

 The specifications call for the hlocks to he 6 in. sc^uare hy k in. 

 thick, while those for the panels prescrihe them to he 6 in. hy 12 in. 

 hy 1 in. thick. These "hoards" are hung vertically in the watet- with 

 the ho ttom suspended 2 feet ahove the mud line. They are usually 

 suspended from some ohject fast in place (such as a wharf or pier), 

 with a weight fastened, to the hottom to minimize the movement which 



may he caused hy tides or currents. The four top panels, which are 

 "teat panels", are numhered 1, 2, 3, and h. The fifth, or control 

 panel, is not numhered. Below this in the series are four test panels 

 numhered 5^ 6, T , and 8. 



2. At the end of the first month's exposure of the hoard, the 

 Ho. 1 test panel and the control panel are removed for suhmission to 

 the Lahoratory; and a new No. 1 panel and control panel are installed. 

 At the end of the second month the No. 2 test panel, which has heen 

 suhmerged two months, and the control panel, which has heen suhmerged 

 one month, are removed and forwarded to the Lahoratory; and a new Ko. 2 

 panel and control panel are installed. At the end of each succeeding 

 month's exposure each successively numhered panel and the corresponding 

 control panel are removed and new panels Installed in their places, 

 until the entire eight numhered panels have heen removed and replaced, 

 whereupon the cycle is repeated, heginnlng with the Ko. 1 panel. ThuS; 

 at the end of 8 months and at the end of each month thereafter, the 

 nimihered panel removed will have heen sutmerged eight months and each 

 control panel for only one month. By this method of removal and 

 replacement of the test and control panels the test may he carried on 

 for as long a period as desired. The control panels, yhich have heen 

 suhmerged for one month each, are of particular value since the 



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