How far back could a modern Royal Navy captain command?

How far back in time could a modern Royal Navy captain still command effectively?

Probably to the late seventeenth or early eighteenth century. Earlier English might still be partly intelligible, but changing naval command vocabulary would make effective command harder.

A modern Royal Navy captain's historical training would help with older ships and battles, but effective command also depends on communication. Clarke initially places the practical limit around the eighteenth century. Another panelist argues that ordinary speech could remain substantially intelligible as far back as Elizabeth I or James I. Clarke distinguishes that from directing a battle with unfamiliar naval terminology and settles on the late seventeenth or early eighteenth century. Regional speech and the need for multilingual intermediaries would create additional difficulties.