1.1 ,This test method covers the laboratory determination of the rate at which organic biocide is released from an antifouling coating exposed in substitute ocean water. The test is run entirely in the laboratory under controlled conditions of pH, temperature, salinity, and hydrodynamics. Analytical procedures are provided for the determination of the release rate of 4,5-dichloro-2-n-octylisothiazolin-3-one (DCOIT), zinc and copper pyrithione (ZPT and CuPT), and N-cyclopropyl-N′,-(1,1-dimethylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine (CDMTD). At predetermined intervals, substitute ocean water samples are analyzed for leached biocide using a suitable analytical technique.