Advices: If you have to dive your boat to ocean floor

[Rosencrantz]

I have noticed many of us has find it difficult to dive the boat to the ocean floor and to stay there without major damages. Well, it can be done and here are my advices:

1. If you are in storm conditions, you HAVE to find water deep enough so the waves won't lift the boat up and hit it back to the bottom. So, maybe 60 meters + is needed for that if in the storm.

2. Get your boat close to the bottom step by step and while doing that, ping the depth if possible.

3. When you are ready, stop the engines and when your speed is 1 - 2 knots, give "Dive" order by hitting D key. DO NOT give a new depth order because this will cause your boat starting again going up and down = you hit the bottom several times. JUST hit the D key and everything should be go just OK.

4. Keep in mind you can't handle the boat just by dive order if you are in shallow waters because the waves will lift your boat no matter what you try to do for that. In RL you could take some more water in (into the saddle tanks, not in the boat!) but that's not possible in SHIII so the dive order is the only way you to "lock" your boat to the bottom.

-RC-

[pyret]

I dont see the meaning with putting yout boat in the bottom.
Does it give less response to pinging or what?
Nice guide anyway!

[Dowly]

I´ve tried several times to hide in the ocean floor, everytime it has resulted on 100% accuracy from the DD´s and I´ve been dead.

[Rosencrantz]

Well, first of all: If you are a hardcore player maybe you have a rule of thumb that you NEVER, EVER stop your boat while submerged because in RL this would cause boat start to loose the depth control. That's why, if you want just to lay down, nice and peacefull, you have to drive to the bottom. (So no more "plotting" the targets course and after that just sitting there, speed 0, in PD, just waiting the target). So, that's the basic or main reason = In RL you can't keep your depth if your speed is 0.

So, in any case you want just lay and wait, you go to the bottom.

There is exeptions in sea conditions. Sometimes you can find the layer where there is cold, very heavy water under and warm, lightweight water on the top, and - if you can set your boat on top of the heavier water, it's possible to stop the engines and the heavy water will carry your boat. But, this is just an exeption and it's also hard to find these layers even they exist (thinking that germans didn't have a proper tool to measure water temperatures). Also to drive the boat on the layer would not be an easy task.

Hope you can get what I mean, even that my english is not that good.

Greetings,

-RC-

[Keelbuster]

For me, it's okay to stchopp while waiting for targets to move into the 90degree position. Sure - i sink by a few meters. Right before my attack, I put on 2kts and move back to PD. No probs.

kb

[don1reed]

Hi Rosencrantz :up:

You said:
(thinking that germans didn't have a proper tool to measure water temperatures).

The following is from Dr. Timothy P. Mulligan's book NEITHER SHARKS NOR WOLVES, here, speaking about duties in the Zentrale:


...The captain, L.I., and Obersteuermann spent most of their time here or close by as a matter of course. A machinist's mate served as the Zentralemaat (control room mate), whose prime responsibility, assisted by one or two enlisted men (each designated a Zentralegast), concerned maintaining the boat's trim while submerged, alternately pumping or flooding small amounts of seawater into or out of the trim tanks. This in turn required precise data--daily updated in a separate logbook--on the weight distribution of fuel and foodstuffs on board. Other duties included managing the air supply while submerged (for example, pumping air from the engine room spaces to the more crowded forward torpedo compartment); maintaining the periscopes; and checking underwater salinity and temperature levels.

This leads me to believe that they had the wherewithal to compute Thermoclines, and the equipment.

btw OT: What a lot of folks don't realize is that the navigators on the U-Boats were mainly NCO's.(Obersteuermann)

Cheers,

[Heibges]

I remember we debated this before SH3 came out. I believe the issue wasn't do much that they couldn't compute them, but that in a tactical sense, there wasn't much use for them.

The uboat operated on the surface the vast majority of the time. They needed to move at maximum speed to get into position to attack convoy.

When they dove, they dove deep. The area between PD and 150m is like the area between trenchlines in WWI, or the baseline and the serviceline in tennis: no man's land.

So if when you were forced to dive, you happened to have a thermal layer above you it was a bonus, but not something you would figure into your tactical plan.

EXCEPTION: In his memoirs, Dönitz tells a story about a uboat commander operating off Cape Town or Freetown in one of the areas where convoys formed up. He was operating in relatively shallow water, and used a Thermal Layer to sneak in, attack, and sneak out again.

[humesdog]

What's the name of the mod that allows you to speed up tc when in shallow water? Does this work when you're on the bottom because I find when I go down to the floor I can only use 1X tc and its pretty boring down there.

[Sailor Steve]

With the default game you should still be able to go to 32x on the sea floor.

SHIII Commander lets you set TC for any value you like.

So does editing your own CFG files. I forget which one, and as I can't post from home I can't tell you right now. I'm nowhere near my own computer.

[Myxale]

From what i read, the resting your boot on the ocean ground was a common technique back then to wait in shallow water, or to rest if this was needed.

The CE had to keep the boot in the direct flow and had to flood mor or less, depending on the sea conditions.

Well...anyway :hmm:

[BigBadVuk]

Well i was hit(rammed) in channel by nasty DD and as a result of heavy flooding in stern i hit the bottom(some 40m)....For the next 20-30 mins the DD was buzzing all around me and droped a LOT of DCs but none come near close to make any further dammage to my sub...Eventualy he left me on the bottom to fix my ship and return to port(i was returning anyway)....so i think there is some conections between sitting on the bottom and detection cappabilities of DD... :doh:

[Torvald Von Mansee]

Hope you can get what I mean, even that my english is not that good.


Your English is FINE!! I'm sure your command of English is superior to mine in whatever language it is that you speak.

One thing which sucks about being an American is that we don't really get any chance to practice other languages (except Spanish, of course). If you live in small crossroads country surrounded by countries all speaking different languages, you WILL know more than one language fluently. That ISN'T the U.S. :damn:

[BigBadVuk]

ha ha ha..nice point there...wanna move to Balkans? :rotfl: maybe?? :-j

[Khayman]

so i think there is some conections between sitting on the bottom and detection cappabilities of DD... :doh:

It does seem to be a tactic that worked for some. The problem however is if the attackers hang around. You're not going to put any distance between you and them, and at some point you're going to have to surface.

[Rosencrantz]

Hello, to all of you, folks!

don1reed wrote:

The following is from Dr. Timothy P. Mulligan's book NEITHER SHARKS NOR WOLVES, here, speaking about duties in the Zentrale:

Quote:

...The captain, L.I., and Obersteuermann spent most of their time here or close by as a matter of course. A machinist's mate served as the Zentralemaat (control room mate), whose prime responsibility, assisted by one or two enlisted men (each designated a Zentralegast), concerned maintaining the boat's trim while submerged, alternately pumping or flooding small amounts of seawater into or out of the trim tanks. This in turn required precise data--daily updated in a separate logbook--on the weight distribution of fuel and foodstuffs on board. Other duties included managing the air supply while submerged (for example, pumping air from the engine room spaces to the more crowded forward torpedo compartment); maintaining the periscopes; and checking underwater salinity and temperature levels.


This leads me to believe that they had the wherewithal to compute Thermoclines, and the equipment.

btw OT: What a lot of folks don't realize is that the navigators on the U-Boats were mainly NCO's.(Obersteuermann)




You might be right, don, but I think I have seen in some former Uboats commanders memoirs they lacked to have proper equipment to measure the under water temperatures and, if I remember right, that they also lacked the full "knowhow" about the undersea conditions (layers etc.) to have them used in full quantity. Sorry, but now I just can't remember what was the source. The other interesting part is, again if I remember this right, in USN they didn't have the equipment we are talking about, right in the beginning of the war (1941 for USN boats), BUT a little bit later. I'm not sure about this but it could be somewhere in 1942 or 1943.
MAYBE THERE IS SOMEONE WHO COULD CONFIRM THESE OR NOT TO CONFIRM THESE? I can try to find info, but I'm not able to do it in next few days.

Anyway, it seems to me pretty odd, if they lacked the equipment. But when you think they could just not to "tie" the normal temperature "tool" (what is that in english?) on the outside of the boat (would be broken when DC'd :rotfl: ) I can think this might be the reason. If I'm right they used somekind of "electric" system with cabels to measure the temperatures. Have to find it out.

What you wrote about the navigators on board, you are right don!

Greetings,

-RC-

[Catfish]

Hello,
you have to know about salinity and water temperature to adjust trimming all the time, but this certainly was not the duty of the captain or "Kaleun/Kaleu" (in german). This was done for trimming purposes at least twice a day or whenever it seemed appropriate - imagine traveling from the Baltic into the North sea, or even to the Caribbean sea.
Measureing temperature and salinity (which certainly interacts) was done for trimming purposes, not primarily to steer the boat in certain layers of the water to intentionally hide from searching warships.
It was well known by U-boat commanders, that e.g. before the U.S. coast there were salinity layers that disturbed the hydrophone of the boat as well as the hydrophone and ASDIC/Sonar of their hunters, and sometimes this helped a U-boat to hide. But as far as i know there was no device that showed a surrounding density all the time like it is done today.

Measuring seawater temperature is not the problem, as well salinity was checked exactly by a spindle floating in a water probe - quite simple but effective.

Greetings,
Catfish

[Rosencrantz]

Thanks for info, cat! Just one q: Isn't it possible to count the density using temperatur and salinity?

Anyway, you just confirmed my thoughts though.

-RC-

[Khayman]

I'm not sure it was well known.

Wolfgang Hirschfeld was senior telegraphist on the U-109 of Bleichrodt. Near Cadiz Bleichrodt saw some vessels through the periscope that were not reported by Hirschfeld who was on the hydrophones. A little later he was called to the bridge to explain why he didn't hear three British warships which could be seen dead ahead.

He said he couldn't hear anything on the hydrophones and Bleichrodt "told me to smash it up. He was in a boiling rage, unreasoning and unreasonable"

Since they had to get past the warships to refuel, Bleichrodt went under them. Hirschfeld started to hear them faintly and said "They can hear as poorly as we did just now. It must be to do with the water layers." Bleichrodt looked at him and said "Smash the bloody thing up I told you. but I'll have more to say about this when we're back in port".

He was true to his word. Hirschfeld had to go to the Signals Office of the 2nd Flotilla and explain himself. Thankfully for him other boats had reported poor hydrophone audiblity near Gibralter. They concluded it was the fast currents and water layers.

This was about June 1941. So before that you could pity the poor telegraphist who had to face his Captains wrath. "Telegraphy is s*it" was something Bleichdrodt said frequently.

[Catfish]

Hello,
but wasn't that the episode where the microphone fuses had all been flooded with salt water when they removed the panels ? :hmm:
Anyway it was not common to hide in layers of different salinity and density intentionally, but accidentally in a way.

Rosencrantz, if you have a spindle floating in water, and this spindle sinks into the surrounding fluid as deep as to show you something like "1,023" on its scale, you have the salinity and the density of typical sea water at the same time - if the spindle is calibrated at e.g. 20 degrees Celsius it will show the exact density if the water has that temperature. If the water is warmer or colder you still have the density, you only would need to recalculate all if you needed the salinity, and you would do that according to some tables. Colder means the spindle does not sink in so deep, warmer means it will sink in deeper. As well fresh or sweet water will let the spindle sink deeper, and the icy salty waters of the North Atlantic will make it float quite high in the water. The salty waters of the Dead Sea would make it float very high.

So what you always need is the density, since this changes with the temperature and amount of fresh water or better the salt/fresh water ratio, all you need is the spindle to read the density and thus adjust trimming. Don't know if that is understandable, err, a link:

http://www.madsci.org/posts/archives/dec96/848609315.Ph.r.html

;)
Greetings,
Catfish

[Rosencrantz]

Hello Cat! Great you did look this conversation again! I don't wan't to start to be a problem but there is something what I don't understand:

First your wrote:

you have to know about salinity and water temperature to adjust trimming all the time,

and then:

But as far as i know there was no device that showed a surrounding density all the time like it is done today.



and third:



So what you always need is the density, since this changes with the temperature and amount of fresh water or better the salt/fresh water ratio,

Everything's clear by this moment. Just what I thought. But:


all you need is the spindle to read the density and thus adjust trimming.

Are you telling me, they DIDN'T have "the spindle"? You can't mean that, because how in h... they did trimming then? Just by "keeping the eye on the bubble" and making notes, how much water they needed to get into the different saddle tanks to keep the boat on the balance? Sure that's possible... :hmm:

BECAUSE: IF they had equipment to get salinity all the time + to get the water temperature all the time, then they afterall got the "density", right?

Sorry to ask again and again, but I got to really intested in to find out the truth in this. :roll:

So, I think I have known the basics but sure there is lack of info considering the technical details. Next I'll surf the link you gave and after that I'll go to uboat.net. Let's get this clear. :up:

-RC-

[Rosencrantz]

Yep! Thanks for the link, Cat. Easy to understand.

I'm just thinking, if they got equipment to get salinity and temperature = they got the density because that's pure mathematic after we know the temp. and sal.

I'll give my quess: It was the temperature they lacked. (I think USN boats got the "temperature tool" quite late in the war. Which doesn't mean, of course, that germans didn't got that earlier...)

Well, next to the uboat.net.

Greetings,

-RC-

[Heibges]

From the Uboat Commanders Handbook:

57.) As regards the condition of ASDIC in relation to the transmitting capacity of the water, it has been ascertained that the efficiency of the submarine-detecting gear is considerably reduced in sea areas with numerous layers of water.

a.) Formation of layes of varying density ("stratification") of the water of the sea occurs after a long spell of sunshine on a calm sea, and also in a high degree in places where there is a mingling of different types of water.............. Continual observation and measuring of water densities and temperatures are therefore important and indenspensible, for establishing the presense of "stratification" when submerging to considerable depths as a means of evading pursuit by position finding.

b.) In additon, position finding is very difficult, and almost impossible, in shallow water of varying depths (sand banks), where there are many wrecks, as well as in narrow bays (Norwegian fjords), as it is usually not an echo that is produced, but numerous echoes, which make it difficult to keep, but more especially to locate, the target.

[Torvald Von Mansee]

ha ha ha..nice point there...wanna move to Balkans? :rotfl: maybe?? :-j

Well...that depends on which country!! :hmm:

[Catfish]

Hello Rosencrantz,
i think you got it all right -
You can calculate salinity if you have density and temperature, and all other combinations, but all a U-boat needs to trim the boat after all is the density - so if you have a spindle floating in a fresh probe you can read from the scale which density the surrounding water has, and thus adjust trimming directly. If a spindle with a given scale of density (which is not automatically equal to the salinity) tells you a certain value you do not need temperature and salinity - just trim the boat according to the observed density - it already incorporates the other values.

If you had the exact salinity of the surrounding water, and the temperature, you could easily calculate the density - but density could be measured directly after all.
If you were in the Caribbean sea maybe you know the salinity for the Caribbean sea is 1,022 - when you use a thermometer to measure temperature you could theoretically calculate the density using the two values, but in reality there are a lot of exceptions depending on sea state, sun etc., so even if you knew all exact values the best way would still be to measure the density directly via spindles.

I take it there were several glass tubes with spindles in it which could be flooded and emptied all the time for testing. As well imagine a metal tube flanged to the inner pressure hull with in-and outlet and a thermometer in it - you can read the temperature of the surrounding water all the time. This tube certainly had two valves to cut off any water if the boat went really deep to prevent breaking of the glass tube that would not withstand a pressure of say 200 m.
Taking temperature is not the problem, but since there was no automatic device like in the later US subs, you would have had to thoroughly control changes of temperature and density all the time if you wanted to take any advantage of different layers for hiding.
As said before i never read of U-boat commanders who intentionally looked for layers of different salinity/temperature to hide - which certainly does not mean anything. Maybe this was thought of as top secret even after the war and the new confrontation during the cold war, so no one wrote about this.

I hope this makes sense :lol:

Greetings,
Catfish

[Rosencrantz]

Yep Cat! You (we) are right.
Germans didn't have a tool compared BT (bathythermograph). The only way to find out the temperature was to take external water in the boat using salinometer for that. Everyone can imagine the results = water temperature quickly changed so that was far out to be an exact method.
Diving officer could note the heavy layer if the boat was in good trim, but as you wrote, there is many parts affecting to layers so they change "all the time". Also, in North Atlantic conditions layers usually lay well down in maybe 600 - 1000 fts, in the depths out of normal operating depth of the boat, especially in early war time. In Pac the situation was totally different, boats could usually easily achieve the layer. So I was reading, it was common that on approach phase USN boat often used to dive to find out were layer laid and after attack just dived to under it and dissapeared.

But, once again we can see, how the germans did loose the "technical war". BTW, BT was a rather new invention and USN did research to find it to be very useful. By early -43 many of the USN boats got the BT.

-RC-