During a loss of ECDIS, the OOD should announce which critical action?

When the Electronic Chart Display and Information System (ECDIS) is lost, shifting to manual plotting is a critical action because it ensures the safety of the vessel by maintaining situational awareness and navigation capabilities. Manual plotting allows the officer on deck (OOD) to continue navigating using paper charts or other navigational methods. This is essential to prevent a potential navigational error or mishap while the problem with ECDIS is being assessed or resolved.

In situations where ECDIS fails, relying solely on other forms of navigation will help ensure that the vessel can maintain its intended course and avoid hazards until the ECDIS can be restored or a backup system can be utilized. This proactive approach supports safe navigation practices and aligns with the principles of seamanship where redundant systems and procedures are essential for safety at sea.