The font is Deutsch Gothic.

I encounted this...thing... twice: On my VIIC career in 1943 (freiherr beckman's U-735) its an interesting event so i'll save those details for the journal :) .

I run a new career in the background while writing Beckman's journal, to check the map and other ingame stuff, and had an interesting experience in a VIIB in 1939. Here it goes:

with inexperienced officers/crew and a watch officer at the helm, she keeps depth less well than with my LI (helm and repair qualification, any medal and promotions i get go to him, first)
The LI was on damage control duty and the 1.WO was at the helm. control room bar was still a full green but she didnt quite do what i told her to do. ordered a crash dive while at periscope depth, to get deep quick without having to press 'D' and '5' manually (and because i had the hope that it might make her drop down as fast as possibly possible :doh: )

didn't allow her to level off, got planes on full dive from 30 meters or so, some rudder movement etc, either way i treated the boat quite badly and settled down at 160 meters. depthcharges coming in, full speed, down to 180 meters, silent running.

from there she started slipping away, as she should from reading all these posts. in the control room I could see the bubble showing a very slight nose-down angle. Planes on full rise (ordered the boat to surface) and 1 knot. still dropping. 2 knots. still dropping. Its only 1939 so the escorts arent really all that dangerous, got her going at 200 rpm and she went back up to 160 meters. from there, 50 rpm and she dropped back down again.

At 230 meters I started to worry about the hull and thats where it gets interesting:
I put my designated LI back at the helm (most qualified officer for the job) and i put all spare hands in the AFT torpedo room. Unless I am much mistaken, this helped: she still slipped down but less rapidly. But presumably the boat is still suffering the effects of the crash dive order bug/glitch/realistic coding event/thingy. Either way, it took 3 knots or more to get her back up. Got up to 120 meters, let her sit there for a while, cruise around for a bit, get the boat to properly trim etc etc. After a couple of minutes cruising at 1/3 at 120 meters i got the rpm down to 50 and she was still stable. down to 160 meters, still stable. down to 180 meters, still stable.

So, if you are all still following me, here is my conclusion: A competent helm crew is able to hold depth quite well but the boat has to be decently balanced. After some harsh manouvering and hurried manipulations, she is not holding depth (especially when you get below operational depth) but a good crew will get her steady after you let the boat trim properly at a bit of speed at operational depth. Having all crew in the forward compartments or aft compartments seems to make a difference too. I can't help but think that the water pressure simply forces the boat down and you need a good team to keep her stable.

is this conclusion way off and simply the result of a crap interpretation of random events? or is the game / GWX actually this cool?

I'll get into my VIIB again and do some more runs to check all of this. I'm also curious whether or not going backwards will help (since the nose is slightly pointing down, even with planes on surface). Keep an eye on the bubble in the control room, you'll see a clue: she points down at 1 knot, thus explaining the slow descent. At 3 knots you'll see her pointing up.

So much for my two cents

Water pressure does not work like that because there is equal pressure pushing up on
the boat as there is pushing down.

which is why I find find the NYGM approach to depth-keeping, where the boat tends to sink, and that of GWX, where it rises, equally off-putting.

In stock 1.4b, (assuming no damage) the boat hovers quite happily with no forward or backward motion, and generally responds accurately to depth changes.

In RL, things were very different. I can imagine there were dozens of things that would influence depth keeping and I seem to remember reading (in these forums) of one LI who was replaced because he could not do that satisfactorily.

However, it always struck me as a smidgeon unfair to model the effects of poor depth keeping without having the means ( see Catfish's post earlier in this thread) to make it better.

Still with SH3's inability to model such complexities, I suppose that the NYGM/GWX both thought that their approach was a reasonable attempt to simulate this form of instability. Not least to help us avoid getting bored and sitting around listening to the gramophone all the time.

Were they successful? Suppose that's for all of us to judge individually. Me?.... I'll settle for the gramophone any day!:D - particularly if it's playing one of Evelyn Kuenneke's songs

PS There was a reduced positive buoyancy option in GWX 1.03. Dunno if that works with 2.1 though - not running that version yet.

Well, the NYGM/GWX way doesn't so much simulate buoyancy problems with stationary
u-boats as it simulates the gameplay implications. i.e. you have to keep a minimum
speed to keep a constant depth.

so what's pushing the nose down at 1 knot with planes on full rise?

Just a technical aside, you could not recharge compressed air while submerged. Simple, since where would the air come from? If you compress the air in the boat, the crew suffocates. Even a nuclear boat must either surface or use a snorkel to replenish compressed air, as the seawater atmosphere plants cannot possibly produce internal air fast enough to allow for compressed air recharge from the boat's interior air.

The only other point I'd make is that pumping water out at depth consumes a lot of battery power, as you have to pump against the outside pressure gradient. To some degree, maintaining forward momentum of a knot or two may have been energetically favorable over frequently moving ballast water in, and then back out.

I think ddiplock's use of the term rant was a poor choice.

Frustrated is the better one. And good it is.

I could give a damn if you sink, surface or get totally away.

All the emotions you expressed tell me you were totally Immersed.

TOTAL IMMERSION. Thats the whole reason for GWX.

AND THEY DID THEIR JOB TO THE MAX. imho :yep: :up:

Do you? Really? Would have thought that if there were no changes in your boat's displacement , then you would be able maintain depth without momentum coming into the equation to any marked degree.

However, I'm no expert in these matters and open to correction.

Where's 1480 - he's good at all this scientific stuff :yep:

edit: Just seen Seafarer's post. Seems I am being corrected. Thanks :up:

I'll still settle for the gramophone though!

In theory, sure neutrally bouyant and your set. In practice though, it proves extremely difficult to achieve. Pumps and controls have lag in them, so it's difficult to achieve the sheer precision that true neutral bouyancy would require.

But mainly, the ocean ain't static. There are currents that move you, and the environment around your boat is in constant flux. Subtle little changes in salinity, temperature and such mean that the goal of true neutral bouyancy is a contantly moving target.

I did several dives in my grad school days in DSV Alvin (to over 3000m depth in a couple of dives). Here you have a little 36ton (DoH - meant 18ton, ie 36,000lbs), 3-man submersible, with mercury trim tanks and pumps capable of moving fairly minute amounts of trim and ballast water around, and even then it was near impossible to achieve truly neutral bouyancy, and at best we could get it really close for a few moments, but that was it.

If the environment was static, it would be easy, but the environment is very far from static, and hence it is not an easy nor simple thing to try to achieve. Even just trying to do it in a WWII era sub would, I expect, prove mentally exhausting for the crew. They would need to constantly fiddle and fuss with ballast controls - it would be a futile attempt. So, far better to keep some way on, and use the control planes for exactly what they were intended for - depth control.

This whole discussion reminds me of a funny story.

My younger brother (50yo) being the prefectionist he is spent 1/2 hour adjusting his baseball cap on his head to my impatience. I wanted to get to the local bar before HAPPY HOUR was over.

As we were walking down the street a big gust of wind blew his hat off and down the street it flew.

He looked over at me and I smiled and said.

YOU DIDN'T ALLOW FOR THE RANDOM EVENT DID YOU.:p

Nah, depth keeping with out speed was impossible unless the boat was sitting on the
bottom and around 2knts was the minimum to maintain accurate depth.

It was impossible to perfectly trim a u-boat's basalt tanks. Even if you did, just one
crew member walking along the boat would be enough to unbalance it. It was
impossible to constantly adjust the basalt tanks accurately enough all the time.

Depth and an even keel where kept by the dive planes, which could be adjusted
easier and reacted much faster than the trim tanks. They needed water passing over
them to work.
Balancing a u-boat with just basalt is like trying to balance a pencil on
the edge of a knife with thick gloves on and tiny people moving around
the pencil.

Generally speaking, a u-boat would dive 1-4 times a day for a trim dive and
hydrophone check. The basalt tanks where trimmed to keep the boat as stable as
possible with slightly positive buoyancy in case of emergency.

:arrgh!:

Thanks for that info, Seafarer (and Letum BTW). Interesting stuff indeed. 3000m Eh! The mind boggles - at least mine does.

Might have known that salinity and temperature would rear their ugly heads! Have just participated in another thread concerning Thermoclines, their causes, and effects on Sonar detection. I had some misconceptions about them too, which 1480 sorted me out on!

Seriously, I do appreciate all this scientific education, having learned absolutely nothing about this subject at school. Mainly due, BTW, to our Science teacher being a Welshman, who had no teeth. As a cover up he spoke with his mouth half shut and had grown a bushy moustache to further disguise his shortcomings in the dental department. No wonder I didn't develop any scientific inclinations!

That's my excuse anyway.

Again thanks many thanks for your input - maybe I'll even give GWX a try. Specially as it appears they seem to have got things about right!!

Personally I don't like GWX's buoyancy all that much.

In reality the boats where trimmed so they had a slight amount of positive buoyancy.
This meant that if the E-motors stopped for any reason the boat would slowly surface,
rather than sink. In GWX you sink.
I am sure there was a reson for doing it this way. It's better than stock anyhow.

There was a mod that had positive buoyancy...can't remember which.

*edit* you haven't tried GWX?! Your, Sir, are mad! :D