Explanation: For compulsory equipped cargo ships operating outside of GMDSS regulations or a VTS, a continuous radiotelephone watch is maintained on **Channel 8**. This channel is internationally designated as an intership working frequency. Its use for continuous watch allows for routine navigational and operational communications between vessels, preventing congestion on Channel 16. While **Channel 16** is the international distress, safety, and calling frequency that all vessels capable must monitor, the question specifically asks for the channel for a "continuous radiotelephone watch" for non-GMDSS/VTS cargo ships. In this context, Channel 8 serves as the primary working channel to facilitate ongoing communications. **Channel 70** is the Digital Selective Calling (DSC) distress and calling channel, used for automated digital alerts, not for continuous voice radiotelephone watch. **Channel 6** is primarily an intership safety and search and rescue channel but is not the designated continuous watch channel for general navigation in this specific scenario.