When should a bilge pump be activated?

Activating a bilge pump when water levels reach the safe operational limit is crucial for maintaining the safety and operational integrity of a vessel. This action helps prevent flooding by removing excess water before it poses a significant risk to stability and buoyancy. The safe operational limit is determined based on the vessel's design and operational guidelines, ensuring that the water does not rise to levels that could compromise the ship’s safety.

Addressing the other choices, activating the pump only when water levels are at an all-time high could lead to dangerous conditions if the water continues to rise unchecked. Similar dangers exist if the pump is turned on when there is no power onboard, as it would not be operational. Additionally, activating the pump solely during a drill may neglect real-world conditions when water levels need to be managed effectively to protect the vessel and crew.