Even subs have to resurface from time to time so they won't die from lack of oxygen, supplies and from lack of sunlight
for the girl subs and the real life ones.
And those poor Maru-yu. Now that they aren't of use they'll going to be fed to the other girls.
Notably, there were no nuclear subs during WWII, so most of them were diesel-electric hybrids. Running the diesel engine takes air, so the sub have to surface (or remain just under the surface by using a snorkel). The subs can move while submerged by using electric motors, but battery life was limited (and recharging them require the sub to surface and run their diesel engines).
IIRC, the IJN subs don't even have snorkels. IIRC, U-511 had one.
So, yeah, IJN subs would remain on the surface most of the time. Presumably they removed U-511's snorkel, causing her to develop a tan.
Nuclear subs are a different matter though. Nuclear reactors don't consume oxygen, and they have boatloads of electricity so they can regenerate oxygen by electrolyzing sea water. Nuclear 'fuel' also lasts for a very long time. Practically, nuclear subs never have to surface, except when going back to port to grab supplies for the crew.
Notably, there were no nuclear subs during WWII, so most of them were diesel-electric hybrids. Running the diesel engine takes air, so the sub have to surface (or remain just under the surface by using a snorkel). The subs can move while submerged by using electric motors, but battery life was limited (and recharging them require the sub to surface and run their diesel engines).
IIRC, the IJN subs don't even have snorkels. IIRC, U-511 had one.
So, yeah, IJN subs would remain on the surface most of the time. Presumably they removed U-511's snorkel, causing her to develop a tan.
The tan still makes little sense for a simple reason... only a fool would do that during the day. Subs covered ground and recharged batteries by running surfaced at night, then dove and moved slowly during the day if there was any possibility of enemy search aircraft being in the area. Even if a target was sighted an attempt was most often made to wait for nightfall to attempt to overtake or position on the surface, only as the last resort or with supreme confidence about the lack of nearby enemy forces would a surface maneuver be made in daylight.
World War II era submarines might have needed to spend time above water, and may even have spent a majority of it above water (when one considers transit time outside combat zones), but they were nocturnal creatures. That's kind of an odd oversight really how we've got light cruiser screaming about night battles while the Submarine often seem to be playing around on beaches and crap in board daylight. The US Submarine branch is the "Silent Service" and most of the European branches tended to be known for similarly dour and steely eyed professionalism, but good luck finding a shred of dignity or guile among the Kancolle subs.
Maybe Japan was different though. The sub force spending it's time dicking around getting sun tans would certainly explain their abysmal war record I suppose.
Day or night doesn't matter when it comes to war. There's no such thing as dive all day and then spend the entire night recharging air supply. Even if they do spend all night recharging they still can't spend the entire day underwater since they still have to resupply oxygen not for the subs but also for the people and get supplies.
That and you're taking this too serious. The girls are tanned because day and night Orel which is, if we take ingame and night battle into account, multiple days and nights of travelling, fighting and pursuing. That and if you ever been to Japan it's much easier to get a tan in certain parts of the areas that are always tropical or have more sunlight than in places like say, Europe or Russia.
Day or night doesn't matter when it comes to war. There's no such thing as dive all day and then spend the entire night recharging air supply. Even if they do spend all night recharging they still can't spend the entire day underwater since they still have to resupply oxygen not for the subs but also for the people and get supplies.
England and America's heavy bomber efforts would like to have a word with you about day or night making no difference in war. I haven't researched WWII submarine habits for a couple years and thus don't have sources to throw around, but I read plenty about the submarine being mostly submerged during the day and surfacing to recharge at night (Key; "mostly." They didn't strictly stay submerged all day all the time.). It's much, much easier to visually spot a surfaced submarine during the day than at night when you need a decent surface search radar setup or constant spotlights/star shells giving away your position to have a respectable chance of detecting them; things merchantmen didn't have and didn't want to do.
Oxygen for breathing would be the biggest hurdle as WWII subs didn't have life support systems like modern ones, but surfacing to vent the ship wouldn't take that long and could generally be done in known safe zones. Supplies don't count; for the most part you get those in port where you're going to be surfaced anyway as you aren't in active combat. Japan did have supply subs, but again, you wouldn't be surfacing two subs next to each other in the middle of the day in hostile territory.
They're subs...what the heck were they doing "above" for so long for all of them to get tanned?
(Somewhat rhetorical since the obvious answer is...obvious).
WWII-era subs spent a lot of their submerged time at periscope depth, which isn't anywhere near "dark" depth. Cruise around at periscope depth during the day in tropical seas, and you're going to get a tan. ... If submarines could get tans. And these can! D'accord! :)
Hey, Shioi! Don't try to tempt Yuu-chan!
And don't get her all tanned (before the second Yuu arrives)!Could you talk... a bit slower... Yuu... can't keep up...No, please don't!Yuu-chan, let's go on a grand adventure to the sea around the Nansei Islands!
We can even go there several times a day! There's the sun, the torpedoes, and the waves, I'm sure you'd come to love it!
Oh and Hacchan could teach you Japanese too. Sir is going to feed us to Yuu-chan!The subs, who were already tanned thanks to long years of hard work in the Eastern Orel Sea.Maru-yu isn't food!
