Advancements in automation, artificial-intelligence, robotics, motion-control, satellite based communications, geo-spatial positioning systems, and real-time machinery control systems have enabled ship designers to consider the implementation of totally automated autonomous or semi-autonomous remotely controlled unmanned vessels to operate in a variety marine and naval applications. The possibility of being able to operate unmanned naval vessels poses several operational benefits and cost savings for naval vessel operators while at the same time introduces inherent risks that must be mitigated through robust system safety and redundancy requirements. Unlike manned vessels, on unmanned vessels machinery control systems will need to act autonomously to replicate functions that are normally performed by human operators. This paper will (a) provide a list of machinery control functions normally done by humans that will need to become autonomous (b) identify key requirement areas that will need to be developed for totally autonomous unmanned naval surface vessel machinery control systems, and (c) provide an update on ongoing efforts to develop standards and requirements for autonomous machinery control systems on unmanned naval surface vessels.