There is a growing threat of cybersecurity attacks within shipboard machinery control systems (MCS). A major cyber security vulnerability in shipboard control systems is in the data message communication protocols. These message communication protocols currently do not have message authentication and verification using encryption methods, specifically message traffic of Programmable Logic Controller (PLC) data. This vulnerability makes these systems subject to man-in-the-middle cybersecurity attacks. PLCs struggle in terms of processing power with large amounts of string manipulations required for cryptographically secure hash values within data messages. This white paper will investigate shipboard MCS message data communications authentication options with respect to network architecture, communication protocols, and vendor equipment. The key objective is to investigate options for data message authentication for peer-to-peer control processors and control processors to operator consoles used in shipboard MCS. The approach will be to consider network architectures such as star, rings, bus, hot backup, and subnetworks and how these architectures influence the selection of vendor-specific equipment. The vendor-specific equipment often limits if not dictates communication protocols. Options for control data message authentication and verification are then limited by these design decisions. This paper will investigate the options both with hardware and software solutions with respect to shipboard control system network architectures and communications protocols.