ITU-R M.1842-1, which is one of the renowned specification for VHF data exchange system (VDES) devoted to maritime mobile applications, has been standardized wireless transmission protocols according to the peculiar characteristics of a maritime communications scenario. Generally, in the Annex-4 of ITU-R M.1842-1, the VHF data link protocols for maritime mobile services are described along with a TDMA frame structure. Physical layer parameters of ship-adhoc network (SANET) are contrived to meet the requirements of the specification. In order to increase the link throughput of real-time services, in this paper, we investigate the performance of the SANET with the multiple antennas, where transmit diversity and multiplexing techniques are employed. Based on the analysis of the packet error rate and throughput under the maritime channel model in a coastline area, we select the efficient multiple antenna schemes for SANET to improve the link reliability.