Why does the internal lighting on submarines go red?

Question

Ive seen a couple of times on films all the internal lighting on nuclear submarines go red, why is this?

Answer 1

Here is the reason real nuclear subs use red lights.  If you enter a darkened room, it takes about 5 minutes for your eyes to mostly adjust to the dark, 30 minutes for entire adjustment.  

When a sub raises the periscope, the crew does not want light to escape out of the scope and be visible to the enemy. Also the person looking through the periscope needs to have his/her eyes adjusted to the dark before the scope goes up.

So before raising the periscope, the control room is shifted to red lights for about half an hour.  The person on the periscope will shield himself and the scope with a curtain to prevent red light from going through the scope.  This also further shields the person on the scope from the red light and makes the eyes better adapted for the dark.

Some will also wear a eye patch to keep one eye adapted for scope use even if in white light.

Ranb

Answer 2

because the bright light will blind the fish

Answer 3

Red as many have said enables night vision to be maintained. This is why the new blue headlights on cars are so bad, they destroy the night vision of the drivers in the oncoming cars and are therefore very dangerous.

Answer 4

they have turned on to emergancy low power battery lighting

Answer 5

This is also the reason why the lights in a submarine are traditionally red when the periscope is in use. The lighting inside the submarine will be bright enough for the submarine crew's eyes to be in bright-light mode, but the eyes of sailors on a surface ship at night will be in dim light mode. This means that the surrace people are less likely to see red light coming up through the periscope than would be the case for white or blue light, but the people inside the submarine still have enough light to see by.

This is also why police cars have red lighting in the interior as well.  So if a sniper were to try and aim at a officer, it is harder to adjust or aim.

Answer 6

heat is a great factor.  the only way to track a sub running deep is by thermal trailing.  all unnecessary heat sources are secured to help deter detection.

Answer 7

Night Vision - when comming up at night you can't wait for your eyes to adjust.  Red Light does not effect your eyes the way white light does..

Surface ships use red lights also on the bridge.

Answer 8

wow lots of submariners here

Answer 9

red light doesn't interfere with vision and cause light blindness

Answer 10

Red light does not destroy your night vision rods. In Air Force flight school we did experiments where half the class wore red lenses a half hour before our night vision classes. As soon as they turned out the lights, we who had been wearing red lenses could see everything, the ones who had just went into darkness could see nothing!

Answer 11

red lights are known as dead lights, becouse you can have them on without waking up the sleeping crew

Answer 12

all of your answers were pretty good, and you have a lot to look at,

but for the record, it takes the eye 4 hours to adjust to night vision, with or without red goggles or red light.

the reason for going to red vision is for the crew to continue to operate while the light is suppressed to a larger extent to surface objects looking for them.

Heat signature in submarines is based on satellites looking for small amounts of warmer water than the ambient sea. To my knowledge this is largely a tracking method for movement not ASW (anti submarine warfare).

ASW depends on the noise of a submarine (the turbine from the nuclear pile, movement of air in the ventilation system and cooling fans or people walking in a sub.

use of active pinging by subs is not done. Instead they rely on listening devices for tracking surface targets.   Thermal layers in the sea can assist a sub in hiding, but there is always a way around that.

Subs can hide from active sonar by many methods..I'm not sure what is classified and what is not so I will not discuss that.

As for a sniper with a rifle and a policeman in a car, God forbid.   if the policeman has a light in the car, be it white or red and you have a sniper of reasonable skill, that man is going to have a bad day.

the ability to see in darkness with mechanical aids, be it a telescope, binoculars or something else depends first on the aperture that is bringing in the light, the quality of the lenses or mirror that is reflecting the light and concentrating the area brought in to a very small focal point.

I use 10 x power binoculars in the guard towers in iraq in night conditions with excellant vision, and resorted to night vision only when needed, as it ruins your night vision without for a while.

Answer 13

Red light in darkness is better to see, that is why they used to use it in a dark room, to develop negatives and prints from a camera film.

Answer 14

Red lighting does not dialate your pupils as much as any other color light, preserving your night vision.  This is why the instrument panels on aircraft are lit red as well.