Twenty-three cast alloys varied around the baseline alloy composition of 3.5 weight percent (w/o) zinc, 1200 parts per million by weight (ppmw) silicon and 150 ppmw indium were prepared and characterized physically, chemically and electrochemically for possible use as sacrificial anodes in seawater applications. At the time of this effort (I 988) a broad range composition had been patented but little had been published regarding the effects of compositional variations. This paper presents and discusses the results from the short-term (14 day) and long-term (ca. 150 days) electrochemical tests from those 1988 experiments.