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Old 07-13-2019, 04:06 AM   #1
Lost At Sea
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Default Red Light questions

Howdy Captains,
Tiny questions, just wondering, no biggie
The red light was used in low light conditions, enabling the crew's eyes to adjust. But...

1. Would the captain switch to red light for the whole night, or just a few minutes only before surfacing ?
2. Only the Control Room is equipped with red light. No red light in the Hydrophone Room. This is how it is simulated in Wolfpack. Is that correct?


Last edited by Lost At Sea; 07-13-2019 at 11:17 AM.
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Old 07-14-2019, 09:10 AM   #2
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I'm guessing it varied among captains. I would think the lighting would remain normal unless under battlestations.

A reel shocker:
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Old 07-14-2019, 04:12 PM   #3
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I was under the impression that it takes 20 minutes or so for your eyes to 'recover' from normal light for night vision.

Although one could just wear an eyepatch.

The TV Show Mythbusters actually tested this and deemed it “Plausible,” here’s the description of their testing:
“This myth works under the assumption that the eye covered with the eyepatch is already accustomed to low light conditions, while the other eye must take time to accustom. The Mythbusters were sent into a dark room with light-accustomed eyes and were told to complete certain objectives. Their movements were hampered by the darkness and it took them five minutes to finish. When they went into a rearranged but equally dark room with an eye that was covered for thirty minutes, the Mythbusters were able to complete the test in a fraction of the time. As a control test, the Mythbusters then went back into the same exact room with light-accustomed eyes and ran into the same difficulty as the first test. The myth was deemed plausible because there is no recorded historical precedent for this myth.”'

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Old 07-14-2019, 08:59 PM   #4
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From Wikipedia, the free encyclopedia

Rhodopsin (also known as visual purple) is a light-sensitive receptor protein involved in visual phototransduction. It is named after ancient Greek ῥόδον (rhódon) for rose, due to its pinkish color, and ὄψις (ópsis) for sight.[5] Rhodopsin is a biological pigment found in the rods of the retina and is a G-protein-coupled receptor (GPCR). It belongs to opsins. Rhodopsin is extremely sensitive to light, and thus enables vision in low-light conditions.[6] When rhodopsin is exposed to light, it immediately photobleaches. In humans, it is regenerated fully in about 30 minutes, after which rods are more sensitive.[7]

Rhodopsin was discovered by Franz Christian Boll in 1876.[8][9]
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Old 07-16-2019, 10:04 AM   #5
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If the wiki isn't proof enough

Accustoming to dark light conditions does indeed take time, like 15 to 30 minutes in the absence of (bright) light sources. I have no RL experience in naval/maritime operations, let alone subs, but it is a well known effect made use of in visual astronomy. After a while the faint stars and the milky way are easier to distinguish. Until a car drives by with it's headlights on the country road in the middle of nowhere where we set up our telescopes. Then it's ruined again.

With normal light from the hydrophone shack being more ambient rather than intense point sources it probably doesn't need to be in red-light conditions there. Looking into a bright (white) point source focusses that light onto your retina and kills the sensitivity. So whoever is up for bridge duty or has chances to look through the scopes would want to have red light. Which does not reduce the sensitivity that much. Since you can't really predict when that is the case I guess it is reasonable to make that a rule to have it red all the time from sunset to sunrise. But who am I, I'm just a landlubber in real life.

p.s. I've watched a bunch of youtube/twitch streams where they suggest rigging for red reduces battery consumption. I would guess that is an urban myth. I see no reason why that would reduce the battery drain by the electric motors.
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Old 10-22-2019, 10:02 AM   #6
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We used to be taught that 30 minutes would get most of your night vision back, but it takes 45 minutes to get it all back. Looking slightly away from the object also helps so that you're not focussing light on the Fovea which is the area of the retina you use when looking at something directly. The Fovea has a much higher proportion of colour receptive cells, and less of the more efficient "black and white vision" ones. So, if you need to spot something in darkness, look slightly away from it. The black and white "rod" cells are closer-packed, and more able to resolve movement, which is why you often catch sight of movement "in the corner of your eye".
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Old 10-23-2019, 05:11 AM   #7
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Good info! I certainly didn't learn all this at school in my days !

I'm still wondering whether the radio / hydrophone room should also be flooded with the red light. Also true with the map and recognition manual.
Both are real killers when switching back and forth to periscope / binocs / UZO views at night, ha!

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Old 11-30-2019, 07:56 PM   #8
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Red light is used at night for another reason: it doesn't flood through the periscope giving away your position.

Like the grill in your microwave preventing microwaves leaking out, the size of the aperture of the periscope pretty much prevents the red light flooding out of the scope, so at night you don't give away your position.

If you use white light, then the periscope would be visible at a distance, and could give away the presence/position of the boat.

You could use another option: get depth-charged "enough" that your bulbs fail and you have no internal lighting... Thankfully we have hand-held torches!

I always go to red lighting when attacking, and all night when it's dark. It also acts as a clock so you know whether it is day or night.
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