In the distributed shipboard environment of interest to the United States Navy, there is an increasing interest in the use of multicast communications to reduce bandwidth consumption and to reduce latencies. Standardized metrics and tools are needed to evaluate the performance of multicast systems in this environment. This paper proposes a number of metrics and data collection and analysis techniques for assessing multicast communications performance. Of particular significance is a metric that correlates message reception among receivers and shows promise in analyzing topology related problems. The MCAST Tool Set (MTS), which uses the metrics and data collection techniques presented, is used to analyze several multicast application scenarios.