What does the Third Substitute signify?

The Third Substitute is a signal that indicates the Commanding Officer is not on board the vessel. This flag is displayed to inform crew and other vessels in the vicinity that the officer in command is absent, which can affect the chain of command and operational authority onboard. It serves as a communication tool within naval and maritime contexts, signaling the need for awareness regarding the command structure and the need for operational readiness despite the absence of the commanding officer.

In a broader context, the other options relate to different maritime signals or procedures that do not specifically pertain to the absence of the commanding officer. For example, the flag that is flown during church services is designated for a completely different purpose, while a personnel recall signal indicates that crew members are to return to the ship. Additionally, the signal indicating five minutes before colors pertains to the raising or lowering of national flags, which is a distinct routine and unrelated to command authority. The importance of recognizing the Third Substitute lies in understanding the implications for leadership and decision-making while at sea.