The current output of full-scale arrays of several anode sizes In use by the Navy for the cathodic protection of ship hulls were determined. Impressed-current anodes formed from sheet steel were substituted for conventional galvanic anodes to reduce the weight and number of arrays necessary to obtain the desired information. The anode sizes investigated were 3 x 12 x 1-1/4 inches, 6 x 12 x 1-1/4 inches, 4 x 4 x 12 inches, 7 x 7 x 36 inches, and 4 x 10 x 60 inches. A 1500-foot steel sea wall located in water with a resistivity of 34 to 38 ohm-cm acted as an unpolarizable cathode. The output currents were determined for driving poten¬tials of 0.1,0.2,0.5,0.7, and 1.0 between the cathode and the anode arrays, hence the data can be used to estimate for any galvanic material both the initial current output of an anode array, and the continuing current out¬put against a cathode polarized to a known potential.nThe anodes in all arrays investigated suffered mutual Interference as indicated by decreased current outputs from individual anodes as the number of anodes in the array increased. It was found that the addition of anodes is more efficient than a moderate separation of anodes in increasing the total current output.
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