Submerged radio messages

[JuanLiquid]

Can an uboot in SH3 send/receive radio messages while it's submerged? I think they could do in real life while they were around 20-30m under water, but I'm not sure how SH3 emulates it. Could you confirm?

[BigWalleye]

Can an uboot in SH3 send/receive radio messages while it's submerged? I think they could do in real life while they were around 20-30m under water, but I'm not sure how SH3 emulates it. Could you confirm?

Yes, they could, although probably not as deep as 30m. The closer the sub was to the transmitter, the deeper it could be. Check here:

http://uboat.net/articles/35.html

I recall an active USN officer posting on the SH4 forum that fleet boats could receive radio messages at a depth of about 60 feet. That's consistent and an independent source. Unfortunately, I can't find a link to the post.

[bstanko6]

My grandfather was a chief radioman in the USN. he was on the last diesel electric boats. Yes they could at shallow depths. And depending on the sea state. According to him.

[JuanLiquid]

Thanks for the replies, however I think it's not emulated in SH3, is it?

[bstanko6]

You can receive messages at 25m or less, not transmit

[jgf]

The reception depends on the frequency. VLF (very low frequency, about 100kHz-200kHz) transmissions can travel quite far underwater, though only to a depth of 20-30ft; the USN experimented with this in the thirties, the antennas were hundreds of feet long, suspended on low towers along the coast. Downside is this frequency band is extremely susceptible to noise, especially since they were using amplitude modulation back then. The system is still in limited use today, on a much lower band (https://en.wikipedia.org/wiki/Lualualei_VLF_transmitter).

Video of dedication of USN VLF station in 1953 - http://www.clipxaab.com/NFdvVXZNUy04VDRY

Also, though I've no idea if Uboats used this, some submarines had antennas on buoys that could be released when submerged and reeled back in, allowing both transmission and reception while submerged. A modern variation of this, using satellite relays, is used by nuclear subs today.

https://en.wikipedia.org/wiki/Communication_with_submarines

[CaptBones]

Lots of inaccurate info here...

VLF is 3-30kHz, wavelengths from 10-100km. Under ideal conditions, a groundwave could theoretically penetrate to a depth equal to it's wavelength. Practically speaking, reception is reliable down to 40-50m, but because of the "noise" problem, it is only useful for slow data transmission. However, not used in WWII, despite experimentation in the '30s and during the 40's. Came into use by the USN and others during the Cold War.

WWII long distance communications were HF; 3-30mHz (short wave radio, encrypted Morse Code...think "Enigma"), wavelengths 10-100m.

HF reception is very workable at keel depths of 10-30m/30-100ft, using horizontal wire antennas, which you can see installed forward and aft of the conning tower on both U-Boats and US Fleet Boats. Neither used "trailing wire" antennas...impractical for the day. You cannot transmit effectively, or at all for that matter, on a "trailing wire" antenna...it's in the water...grounded. WWII boats could only transmit when surfaced; using either the aforementioned wire antennas or whip antennas, either retractable or mounted fore-aft horizontally (to avoid vibration when submerged). Late in the war, Fleet Boats could transmit at periscope depth with periscope-mounted or mast-mounted antennas, but those were VHF/UHF for "line of sight" tactical voice RT (radio telephone) communications with nearby friendly units.

ELF is used today; 3-30Hz, wavelengths from 10,000-100,000km. Very slow data transmission rate, but very reliable reception at deep depths; let's say that's "in excess of 100m". ELF reception depends on use of long trailing wire antennas. Think amplitude modulation on a radio wave at least 10,000km long! Frequency modulation (single sideband or dual sideband) is just slightly more workable.

Satellite data links use UHF/EHF with buoy-mounted and mast-mounted antennas. But the philosophy is still that submarines are the "Silent Service"...listen but don't transmit unless absolutely necessary.

[JuanLiquid]

Thank you, I wasn't expecting a deep explanation, I only wanted to know about if my uboot could receive the signal while it's underwater in SH3. I would hate losing any news from a wolfpack while I'm sneaking a convoy.

Good explanations anyway :Kaleun_Applaud:

[Angel4532]

I receive radio messages and news in SH4 at 300 ft. Is there a way to stop that?

[Anvar1061]

I receive radio messages and news in SH4 at 300 ft. Is there a way to stop that?
https://www.subsim.com/radioroom/images/smilies/Kaleun_Confused.gif
This is not a sh4 theme.
No

[Captain Drastic]

I routinely cruise at 21 meters (not correct, sorry, see below) in order to receive messages while submerged in GWX. In fact, I have this modded into my keyboard commands in place of snorkel depth, which then becomes the order "Go to cruising depth". Snorkel depth I set manually, although for the Type XXI I set it the same as periscope depth. You can still only transmit while surfaced, though.

***Further testing shows 21m too deep for messages. 19m gets messages.

[Shadowblade]

I routinely cruise at 21 meters in order to receive messages while submerged in GWX.

why 21 m? I use periscope depth (13 m) usually so I can check surroundings when anything is detected.

[Hooston]

in rough weather there is the risk of the conning tower being exposed at periscope depth. Also in very calm conditions with clear water an aircraft could spot a submarine at periscope depth.
Are these in the game? No idea.
i also tend to sit at around 25m when cruising submerged.

[Captain Drastic]

I apologize for going back and editing the previous post, but I didn't want something incorrect in the record.
It turns out that 20 meters is the deepest depth that is both below periscope depth and also able to pick up messages. However, if the depth goes just slightly below 20m then no messages. So 19m is the best. Periscope depth is known as the danger zone because of the risk of colliding with surface vessels.
However, 19m is still not enough to clear all surface vessels. After more testing I found that even 21 meters is not deep enough, you can get your conning tower smacked by a large tanker. In order to be safe, I am going to be setting my cruising depth below 21m, 25m as Hooston said sounds good. That means to receive messages you have to come up to 19m "comms depth" at certain points in submerged cruising.
And yes, the conning tower can get exposed in rough weather at periscope depth- the game models this- it's probably worst in a Type II. I have never been spotted by aircraft at periscope depth, so is probably not modelled in the game. Still, nice to have a camo paint scheme in the Med, just in case.
All of this is what I found running GWX, I don't know if other mods are different.

[Shadowblade]

@Hooston - good, for rough weather going deeper makes sense.
I dont think that spotting comletely submerged uboat by ASW aircraft is ingame. But when they saw you diving then sure, they will try to attack you.



However, 19m is still not enough to clear all surface vessels. After more testing I found that even 21 meters is not deep enough, you can get your conning tower smacked by a large tanker. In order to be safe, I am going to be setting my cruising depth below 21m, 25m as Hooston said sounds good.

I never had this issue, because my hydrophone crew would detect nearby ship and after planning her course I would see if the ship is on collision course (for neutral ship). If it would be enemy ship then I would try to sink it first.

[Captain Drastic]

What depth you cruise at is really not a game problem, it is part of your style of play. Some people like a more immersive playing style and try to follow the instructions given in the WW2 U-boat commanders handbook for this type of thing. Other people just do whatever the game lets them get away with. As far as being immersive the list of ways to work with the game is seemingly endless.
The Just Follow Orders Mod is a great example of this. Some people love it for the added realism, other people don't want to bother with stuff like that. I myself am a big history buff so I like more historical details in my games.

[Hooston]

My central heating boiler is in my bathroom and it has just sprung a leak. Many people would see this as a crisis, but for me it is an opportunity to take the SH3 experience to the next level.

[Shadowblade]

@Captain Drastic (https://www.subsim.com/radioroom/member.php?u=242753): well, I follow the historical guidelines like G7a/G7e torpedo storage, but I didnt read that uboats had any recommended cruising depth :03:

[Captain Drastic]

I'm not recommending all players have the same style of play. Some just don't have the time to go into all the details.

From "The Submarine Commander's Handbook"-
29.) The danger of a surprise attack exists, in particular, when the submarine comes to the
surface, especially after traveling long distances at considerable depth. When coming up
from a considerable depth, an all-round sound location should therefore be carried out at a
safe depth, where the submarine cannot be rammed; i.e., at a depth of approximately 20 m, at
"sound-location speed." Next, the submarine should go rapidly through the danger zone at
periscope depth, with the periscope raised; careful all-round look-out with and without
magnification - submersion up to 9 m, depending on the weather, then lower the periscope
altogether (see No. 23) and surface at high speed. The manhole of the conning tower is
opened as quickly as possible, and the commander - with, at the most, one man who is
especially good as a look-out - goes up. It is not until the surface of the sea has again been
examined with binoculars, in every direction, that the compressed air cells can be completely
emptied of water.

This seems to imply a "safe depth, where the submarine cannot be rammed; i.e., at a depth of approximately 20 m" , so 20m or below is safe cruising, commander's discretion.

[Captain Drastic]

I asked Chat GPT for an answer and here's what it said-

"During World War II, German U-boats typically cruised at depths of 50 to 70 meters (165 to 230 feet) while submerged. This depth allowed them to remain relatively safe from detection and attack while conserving battery power."

We must respect our new AI overlord. hahaha.

[Gorpet]

https://www.subsim.com/radioroom/images/smilies/Kaleun_Confused.gif
This is not a sh4 theme.
No

I have rolled back out of my chair. LOL Tks.

[Gorpet]

I asked Chat GPT for an answer and here's what it said-

"During World War II, German U-boats typically cruised at depths of 50 to 70 meters (165 to 230 feet) while submerged. This depth allowed them to remain relatively safe from detection and attack while conserving battery power."

We must respect our new AI overlord. hahaha.

Look,Pumpkin DeepSeek is the new AI.

[Captain Drastic]

We cannot know the ways of the AI overlords.