Grok says:

"Rig for Red" is a term primarily used in the context of naval submarines, particularly those from the U.S. Navy during World War II and possibly extending into later periods. Here's what it means:

Purpose: The command "Rig for Red" involves switching all interior lighting to red lights or significantly reducing the intensity of lights to red. This practice is designed to preserve the night vision of the crew, especially when the submarine is preparing to surface or come to periscope depth at night.

Usage: This term was part of standard submarine phraseology to ensure that crew members' eyes adjusted to low light conditions, making it easier for them to see outside in the dark without being temporarily blinded by brighter interior lights.

Historical Context: Over time, the use of red lighting has been debated for its effectiveness. There has been a shift towards using blue lighting in some modern submarines because blue light is believed to be less disruptive to the natural sleep-wake cycle (circadian rhythm) and might offer better visibility for certain tasks.

Beyond Submarines: While its origin and primary use are naval, the concept of using red light for night vision preservation is also applied in other fields like astronomy, where observers might "rig for red" to maintain their night vision while making observations or navigating in the dark.