And that any other light that is NOT red is either the enemy or intended for the viewer.
CIIW, LonePalm, but red-light in a sub improves focus on the lighted terminal used by the crew.
“...lighted terminal used by the crew.”
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What ‘terminal’?
WWG1WGA
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)
All good explanations for surface ships. There’s one more step for subs. They have a “ready room” set aside for the next deck watch to stay for the last half hour or so before watching topside. And sometimes the control room goes red if the driver wants to look thru his optics at night. While nukes don’t spend much time on the surface they do occasionally dock, navigate by star, or otherwise rendezvous, at night. The red light conditioning definitely helps with night vision. The electronics guys, the spooks, have their own reasons for going “red” sometimes.