Positive bouyancy

[svenks]

(and I hope I splled THAT right)...

First of all: Happy New Year to all Kaleuns, Admirals, Onkels and Vaders.
I'm simply having a blast with GWX - What a splendid, outstanding... Well, I'm really out of words here! So lets just say. I love it! Thank you GWX group!

I got one problem, though: The positive thing from subject (I won't misspell it twice): I don't feel it's right. Now, I don't doubt that normally the boat would trimmed for a slight positive <you know>, but there are some problems with that approach. As other people also have mentioned, you risk starting a mission with half of your tower above water:o , and the only way to cure that is to increase speed - just what the destroyer in front of you would like to see.

It also means goodbye to sitting on the bottom...

And then there is this: All of a sudden, Ahead Slow submerged is not 3 knots - but only 2 (= even more tendency to drift up). A closer investigation revealed that the reason is that my bow dive planes are not level - they are pointing down, thus increasing both drag and noise.
I've never been on a sub, but I've read quite a lot of them. I'm pretty sure that you would always try to keep your planes level, same as in an aircraft. Drag is everyones enemy. Instead of using the planes, you would use the trim tanks to pump some more ballast to the front.
Now I know, we haven't got trim tanks in SH3, but I still feel the approach to postive <there it was again> is not optimal. Maybe some other way could be thought of.

Finally: I've seen some pretty harsh responses to people pointing out one problem or another - as THEY see it! As I did state in the beginning, I LOVE GWX, and this is not a case of "I WANT". I've tried as best I could to explain why this 1 (of a 1000!) feature is not optimal, AS I SEE IT. If you don't agree, then please do as the guy in Red October: "Cut the guy some slack". Thank you for your time.
Now back to GWX (enroute to AM54 - Fette Beute?)

BRGDS
Sven

[bigboywooly]

If the problem is starting single mission at a not deep enough depth then thats a simple fix
Will relook at the single missions for the Jan 31st update

The reason the silent running speed was changed to 2 kts as that IS silent running
3 kts will get you detected

2kts should be enough to keep the same depth
You just need to keep an eye on your depth when creeping up on a target

[fredbass]

If you're going too slow or stopped and you observe your boat rising, then set your depth a few meters lower than what you want and you'll be set.

[Letum]

It's not true positive buoyancy either, you only raise a few feet and never surface.
With true positive bouncy you should rise until you can rise no more or you start the motors.
Its not a game killer, but it's something the GWx Devs might want to revise if possible.

[Kpt. Lehmann]

It's not true positive buoyancy either, you only raise a few feet and never surface.
With true positive bouncy you should rise until you can rise no more or you start the motors.
Its not a game killer, but it's something the GWx Devs might want to revise if possible.

Believe me... given the code and options available for us to work with... there is no "perfect" approach to variable fine trim... positive or negative.

SH3 just doesn't allow for it and the currently accepted work-arounds are incredibly fiddley.

It is highly doubtful that we will revisit the issue.:( Sorry.

[shegeek72]

If I blow the ballasts with helium will my sub rise out of the water and into the air? ;)
--
http://tarafoundation.org/sh3_dark_gw3r.jpg

[Tikigod]

I have a strange issue where the uboat never reaches the depth I order it to. If I order to dive to 20 meters it will dive to about 17. If I order to dive to 30 meters it will dive to 28. The dive planes always look like they are pointed down but the boat will continue to run 3-4 meters shallower than ordered. If I want 20 meters I usually have to order to dive to 23-24 meters. This usually happens when running at 1/3 speed. Is this a new GWX feature? I'm never running silent running when I am doing these manuevers.

[bigboywooly]

:hmm: not noticed that
Will have to try it out

[Kpt. Lehmann]

I have a strange issue where the uboat never reaches the depth I order it to. If I order to dive to 20 meters it will dive to about 17. If I order to dive to 30 meters it will dive to 28. The dive planes always look like they are pointed down but the boat will continue to run 3-4 meters shallower than ordered. If I want 20 meters I usually have to order to dive to 23-24 meters. This usually happens when running at 1/3 speed. Is this a new GWX feature? I'm never running silent running when I am doing these manuevers.

The only "true" silent running in SH3 (and in real life) is a complete stop.

"Silent Running" is triggered in-game when you order it as usual... and it greatly reduces your sound output.

However, any propelled movement of your sub creates noise in SH3/GWX. (Though still greatly reduced by the "Silent Running" order when you give it.)

Enemy sensor sensitivies have been increased. No noise output changes have been made. Increased sensor efficiency made increasing in noise output unecessary. Some noise is always there anyway.

The fiddley depth keeping and dive plane angles are is a by-product of the positive bouyancy modelled into GWX.

The dive planes themselves in SH3 make no noise. The down angle is simply produced by the boat trying to go to the depth ordered by you. The only way to change that ATM is to remove the positive bouyancy.

[hocking]

One thing I noticed, and I am sure this is a GWX realistic effect, is that your boat will react to how you have men in various compartments of your UBoat. I noticed the other day that after I dove to 160 meters in m VIIB, and then went to silent running, I actually sank deeper as I went. I finally caught it when my Helmsman kept telling me we are reaching critical depth. When I looked, I had sunk all the way to 180 meters. I did this over and over again, and I could not figure out what on earth was causing this. It had never happened before.

I then noticed that I had my forward torpedo room completely full of men, but they weren't doing anything because we were running silent. I decided to disperse them throughout the boat in the crew quarters. After this, my boat would go to 160 meters and stay there. Bottom line, how you have your crew stationed throughout the boat appears to effect the trim of the boat dramatically.

[Iron Budokan]

Wow, this is amazing if true! :o

Could we use this feature to dive even faster once we're under water?

[Deamon]

One thing I noticed, and I am sure this is a GWX realistic effect, is that your boat will react to how you have men in various compartments of your UBoat. I noticed the other day that after I dove to 160 meters in m VIIB, and then went to silent running, I actually sank deeper as I went. I finally caught it when my Helmsman kept telling me we are reaching critical depth. When I looked, I had sunk all the way to 180 meters. I did this over and over again, and I could not figure out what on earth was causing this. It had never happened before.

I then noticed that I had my forward torpedo room completely full of men, but they weren't doing anything because we were running silent. I decided to disperse them throughout the boat in the crew quarters. After this, my boat would go to 160 meters and stay there. Bottom line, how you have your crew stationed throughout the boat appears to effect the trim of the boat dramatically.

I'm just woundering which settings in which files determine this ?

[Albrecht Von Hesse]

One thing I noticed, and I am sure this is a GWX realistic effect, is that your boat will react to how you have men in various compartments of your UBoat. I noticed the other day that after I dove to 160 meters in m VIIB, and then went to silent running, I actually sank deeper as I went. I finally caught it when my Helmsman kept telling me we are reaching critical depth. When I looked, I had sunk all the way to 180 meters. I did this over and over again, and I could not figure out what on earth was causing this. It had never happened before.

I then noticed that I had my forward torpedo room completely full of men, but they weren't doing anything because we were running silent. I decided to disperse them throughout the boat in the crew quarters. After this, my boat would go to 160 meters and stay there. Bottom line, how you have your crew stationed throughout the boat appears to effect the trim of the boat dramatically.

I noticed the same thing way back with GW1.1.

I was running deck awash, and I couldn't get the bow spray to stop. So I loaded up the forward torpedo room and bow quarters and voila! That tipped the bow down enough to push it under and stop the spray.

[hocking]

This is a very realistic effect that UBoat Commanders dealt with all the time. They would actually have to constantly change their trim settings as they ate up food, shot torpedos, threw out trash, and anything else they did that effected the weight in various compartments. This would obviously change as the patrol went on day after day. So, they would just dive down, and reset all trim settings so when they are in an emergency dive they will have all this taken care of in advance.

There was a standing order on all UBoats, no crew movement between compartments when the boat was submerged. You were to get to your assigned compartment, and stay there while submerged unless their is an emergency somewhere. This makes nothing but all kinds of sense.

[svenks]

Hi all - and thanks for every reply.


The reason the silent running speed was changed to 2 kts as that IS silent running


I wasn't referring to running silent, but to selecting Ahead Slow. That speed used to be 3 knots in a VIIB, but is now only 2 due to the bow planes pointing down.

OK, so you CAN sit on the bottom... But how will you get there? To avoid damage, you can't be moving forward. If you don't move forward, the PB <hehe> thing will keep you from going downwards.

As for the noiseless dive planes: I was referring to the sound of the water around the planes, not their movement. All things being equal, there will be more disturbance around a non-level plane... If that is modelled into SH3 is another matter, however.

To sum up, if there is no other way to implement it, then "So be it, Jedi". I can live with it. Thanks again for all the comments and replies.

BRGDS
Sven

[Jan Kyster]

The first convoy U-33 met, was in very bad weather at night. Only had sonar contact, but was in the right position ahead of it. After a long wait at 20 meters we decided to go to periscope depth and have a peek. Pitch black, stormy and *very* heavy rain... all I could see in my attack periscope was rain pouring down and blackness... but wasn't the "black" moving? Suddenly the black had a "zig" pattern across it?! and just as I realised what it was, night went into day when the searchlights went on and all hell broke loose as that Swan destroyer spotted me :o I guess she was 100-120 meters away... it was in grid AM15 and as the convoy was heading for home we decided to leave it and spendt the next few hours escaping the destroyers...

Next convoy was an entirely different story though. 10:00 morning, bright and sunny, sea was smooth as silk and we had plenty of time to line the boat up for the attack. Was well ahead of the convoy, I ordered PD, "all stop" and went to my maps for planning the attack. As I'm sitting there, I swear I could hear the shell and then came the "we're under attack" :huh: Had a quick look in periscope and there she was... 5000 meters away, guns blazing and under full steam towards us! Took a outside look... our conning tower was above water!!! wth?! Dived to 50 meters before silent rigging, a sharp 90 degree turn and ordered 100 meters depth... "nah, you can have 69 meters, skipper"... wth?! even the threat of a court-martial would not persuade my helmsmen to go deeper...

We broke of, went north and did some divetesting instead and decided we could not live with this boat. Or more precise, it will see us killed sooner or later. And as a commander, I can simply not accept my orders are not complied...

Now the boat is "fixed". It can sit still on surface and slowly sink/rise to any desired depth, just like a real sub. And so far I haven't found any problems with my altering of GWX. Oh, and don't get me wrong. You'll not find any bigger GWX fan anywhere, but this buoyancy behavior is not correct. Besides being lethal! What if the batteries dies?

Link to picture showing dive/rise sequence... http://www.sfgpl.dk/pics/sh3/div/diving.zip
Send a pm for altering method...

@hocking: ...constantly change their trim settings as they ate up food...
Well, not until they made a dump and flushed it outside the ship. Of course, just nit-picking :rotfl: but as you say, the trim and drain system is an essentiel must have. Still haven't recieved my type VII manual, but here's a link for an american sub manual... http://www.maritime.org/fleetsub/trim/index.htm

Happy hunting! :arrgh!:

[Hartmann]

One thing I noticed, and I am sure this is a GWX realistic effect, is that your boat will react to how you have men in various compartments of your UBoat. I noticed the other day that after I dove to 160 meters in m VIIB, and then went to silent running, I actually sank deeper as I went. I finally caught it when my Helmsman kept telling me we are reaching critical depth. When I looked, I had sunk all the way to 180 meters. I did this over and over again, and I could not figure out what on earth was causing this. It had never happened before.

I then noticed that I had my forward torpedo room completely full of men, but they weren't doing anything because we were running silent. I decided to disperse them throughout the boat in the crew quarters. After this, my boat would go to 160 meters and stay there. Bottom line, how you have your crew stationed throughout the boat appears to effect the trim of the boat dramatically.

some one tried to sit in the bottom with the torpedo room filled with men ?? :hmm:

if the crew in compartments has influence in buoiancy perhaps could help if you want stay stopped in the bottom.

if this is modelled were is the weight data of the crew ?? or it takes a generic value ?

[Txema]

Kpt. Lehmann,

First of all, I want to say that I love GWX. Now I can't play SH3 without it. What an excellent work !!!

However, since the positive buoyancy feature is a bit controversial and as you have stated there is no perfect solution for this issue, I want to suggest you to consider releasing a mod for GWX (to be enabled with jsgme) to allow the player to desactivate it. As it has been suggested in this thread, we could consider that the captain orders his officers to keep the U-boat at a specific depth, and that it is the responsability of the officers to achieve that depth, and that the officers are skilled enough to achieve it. It sounds good to me !!!

What do you think??


Txema

[Samwolf]

Kpt. Lehmann,

First of all, I want to say that I love GWX. Now I can't play SH3 without it. What an excellent work !!!

However, since the positive buoyancy feature is a bit controversial and as you have stated there is no perfect solution for this issue, I want to suggest you to consider releasing a mod for GWX (to be enabled with jsgme) to allow the player to desactivate it. As it has been suggested in this thread, we could consider that the captain orders his officers to keep the U-boat at a specific depth, and that it is the responsability of the officers to achieve that depth, and that the officers are skilled enough to achieve it. It sounds good to me !!!

What do you think??


Txema
:up: IMHO, that is what I have a crew for, to keep the boat in trim.

[Hartmann]

Yes it´s true

is something called delegation, you order things and your crew do this.

when commander is in the attack periscope waiting a destroyer and says "maintain the deep !! and the X.O give the orders to the crew in the planes controls and pumps triming the boat.

could be interesting a option with neutral buoiancy or vanilla via jsme

[Kpt. Lehmann]

Yes it´s true

is something called delegation, you order things and your crew do this.

when commander is in the attack periscope waiting a destroyer and says "maintain the deep !! and the X.O give the orders to the crew in the planes controls and pumps triming the boat.

could be interesting a option with neutral buoiancy or vanilla via jsme

Well, I can understand where you're coming from a little.

HOWEVER, you need to know that reverting to neutral bouyancy will also remove the boat handling dynamics on the surface as well... no more tossing and bobbing like a U-boat should.

In a small way, reverting back to neutral bouyancy will make your boat inherently less noisy too... because you spend less time maneuvering... causing the enemy to hear you less often. Therefore, the ASW package would be weakened in GWX... which I feel to be a strong point.

Removing it will also screw up the usefulness / accuracy of engine upgrades in GWX. (That's a subject unto itself.)

Are you really sure you want to remove this? To remove the one thing... you harm other intended effects... and you can see a tiny example of how everything is interlaced / connected to something else in GWX.

It isn't really that hard to get used to it ya know.

If you are really sure you want it removed... I'll make a modlet and release it here tomorrow or the next day. (Not feeling too well ATM.) Keep in mind that it will not be included with future GWX updates as an optional mod or otherwise... and no offense to anyone but I'm not going to make a habit of making a bunch of modlets to undo this or that feature. There's no way for us to make everyone happy.

Besides, you don't want to delegate everything away to the point that you are simply a passenger do ya?

[Samwolf]

HOWEVER, you need to know that reverting to neutral bouyancy will also remove the boat handling dynamics on the surface as well... no more tossing and bobbing like a U-boat should.

In a small way, reverting back to neutral bouyancy will make your boat inherently less noisy too... because you spend less time maneuvering... causing the enemy to hear you less often. Therefore, the ASW package would be weakened in GWX... which I feel to be a strong point.

Removing it will also screw up the usefulness / accuracy of engine upgrades in GWX. (That's a subject unto itself.)

Are you really sure you want to remove this? To remove the one thing... you harm other intended effects... and you can see a tiny example of how everything is interlaced / connected to something else in GWX.

Thanks for the explanation, Kpt. Lehmann, that info is good to have, I like all the other new dynamics in GWX. I don't think I'd be willing to give up all the rest to remove the positive boyancy even though I agree with the idea of the crew being able to maintain trim on my orders. Looks like another limitation to the SH3 engine that forces us to compromise on the the features we'd like to have.

[JohnnyBlaze]

Not sure what is more realistic, but I find the negative bouyance work better in game. atleast for me.
Might know the effect from nygm anti humming bird mod.

The advantage is that when running silent evading the DD's you could still get deeper without accelerating. The method I used was to crash dive and then move on extra silent at 1 knot and the sub went deeper without even ordering a depth. IIRC it required a 2knots of speed to maintain depth.

As you may notice I was a long time NYGM 2 user, but switched to GWX after it's release. I might never go back to nygm, but this sure is something I miss from earlier experiences


Just my 2cents..

But you did awsome with GWX. Thank you guys for that

[Hartmann]

Yes it´s true

is something called delegation, you order things and your crew do this.

when commander is in the attack periscope waiting a destroyer and says "maintain the deep !! and the X.O give the orders to the crew in the planes controls and pumps triming the boat.

could be interesting a option with neutral buoyancy or vanilla via jsme

Well, I can understand where you're coming from a little.

HOWEVER, you need to know that reverting to neutral bouyancy will also remove the boat handling dynamics on the surface as well... no more tossing and bobbing like a U-boat should.

In a small way, reverting back to neutral bouyancy will make your boat inherently less noisy too... because you spend less time maneuvering... causing the enemy to hear you less often. Therefore, the ASW package would be weakened in GWX... which I feel to be a strong point.

Removing it will also screw up the usefulness / accuracy of engine upgrades in GWX. (That's a subject unto itself.)

Are you really sure you want to remove this? To remove the one thing... you harm other intended effects... and you can see a tiny example of how everything is interlaced / connected to something else in GWX.

It isn't really that hard to get used to it ya know.

If you are really sure you want it removed... I'll make a modlet and release it here tomorrow or the next day. (Not feeling too well ATM.) Keep in mind that it will not be included with future GWX updates as an optional mod or otherwise... and no offense to anyone but I'm not going to make a habit of making a bunch of modlets to undo this or that feature. There's no way for us to make everyone happy.

Besides, you don't want to delegate everything away to the point that you are simply a passenger do ya?

Thanks for the explanation :roll: , i don´t though about that an a small change could need a lot of work and could screw another cool features in the GWX..:oops:.

perhaps is better have positive bouyancy and not remove surface dynamics or asw..engines... :hmm:

see how linked and connected are the diferent features of GWX gives an idea of the difficult and huge task of put all together in one pack.

thanks

[johan_d]

anser is easy.. what did the real thing do?

I personally like the positive, it gives need to drain the batteries, do something, action, and keep alert.
Keep it!

Johan

[svenks]

anser is easy.. what did the real thing do?

I personally like the positive, it gives need to drain the batteries, do something, action, and keep alert.
Keep it!

Johan

Yeah, well - I LIKE it too, for the same reasons you give - it makes it a bit harder!
I just don't think it's really realistic. Look, if you were in danger of breaching the surface under a destroyers nose, what would be most realistic to do: a) Accelerate or B) Add some water to the trim tanks.
Since we don't have the tanks, we're stuck with option a) when we have positive bouyancy (getting confident here). If we didn't, we could simulate adding water and slowly sinking (or at least not rising).

But I agree with the good Captain: If it breaks other things, let's not mess with it.

EDIT: After spending most of last late evading 3 escorts, I must say that I WILL be interested in such a modlet. Reason: I had to go real slow, like 1 knot, and in 1 hour I had lost 20m of depth. Furthermore at this stage BOTH set of dive planes were fully deployed - NOT realistic, since that would have placed my boat vertically :) And In real life, you would just have taken on some more water.


I I certainly agree, that shan't have a whole swarm of enable this/disable that modlets. But if you one day come up with a good idea to how I can bake my cake and eat it... No wait, that was wrong... Anyway, if you think of something, do let us know :know:

BRGDS
Sven

[AS]

Totally agree with you. GWX´s positive bouyoncy is not realistic at all, especially when running silent: as no U-Boat is perfectly sealed up it always takes on water, so when diving it gets heavier, not lighter. When on silent running you avoid any noise including the pumps that normally get rid of the water that´s coming in. So you would either increase speed a bit OR pump/blow ballast OR sink deeper.

In real life there were many cases were the U-Boat could not be kept stable without increasing speed, but without the engines they just had to blow ballast, else they would have SUNK, not SURFACED.

Cheers, AS

[Hartmann]

Totally agree with you. GWX´s positive bouyoncy is not realistic at all, especially when running silent: as no U-Boat is perfectly sealed up it always takes on water, so when diving it gets heavier, not lighter. When on silent running you avoid any noise including the pumps that normally get rid of the water that´s coming in. So you would either increase speed a bit OR pump/blow ballast OR sink deeper.

In real life there were many cases were the U-Boat could not be kept stable without increasing speed, but without the engines they just had to blow ballast, else they would have SUNK, not SURFACED.

Cheers, AS


This was very well simulated in "Command Aces of The Deep", silent running stop all pumps and the sub becomes heavier. Also include a Bilge gauge that show the level of water.
stay very deep at silent running a lot of time was difficult .

Sh3 is limitated in this aspect

[Kpt. Lehmann]

Totally agree with you. GWX´s positive bouyoncy is not realistic at all...

Negative ghostrider, that is an opinion... It is not fact. Our research indicates that U-boats were trimmed in the positive... UP is where the air is and DOWN is where death is after all.

Wouldn't you rather have a positive trim if you lost all power?

Trim was an element that required constant management by the crew... The crew took into account leakage and gradualy incresing weight.

What we need... is the ability to adjust trim, or a situational dynamically changing physical balance of the U-boat.

This we do not have.

I will not just stick everything back to neutral bouyancy for the reasons I mentioned above.

Concerning the moddable CODE our implementation of positive trim is no less "realistic" than modding the trim negative.

[svenks]

What we need... is the ability to adjust trim, or a situational dynamically changing physical balance of the U-boat.


Hi Captain

You are SO very right here: Of course in real life, the boat was trimmed up or down as needed in the current situation. Therefore saying that postive or negative B is unrealistic is wrong, so let's have no more of that.

I really haven't a problem with positive B (or negative for that matter), only with some of it's side effects:up:

So we're caught between a rock and 3 hard places:
Positive B: You can't sit on the bottom, you constantly drift up (at the wrong times too:o ), and your depth rudders are doing overtime.
Neutral B: Say goodbye to some of the nice new dynamics in GWX.
Negative B: Same as for neutral + the risk of sinking slowly to chrush depth.

I understand your reluctancy to revert to Neutral, especially after all the hard work and research put into GWX on this point. However, you did mention a modlet - could you perhaps give us a chance to try it out?

With the deepest respect for your and the group's work,
BRGDS
Sven

[Lanzfeld]

If you were to change the positive B to negative B in GWX would that mess up the boat behaviour as well?

[Kpt. Lehmann]

If you were to change the positive B to negative B in GWX would that mess up the boat behaviour as well?

Most definitely... the two hold hands very tightly. It truly is one thing or the other.

I'm sorry.

[Letum]

There was a mod with negative buoyancy, not nice tho. You really don't want to sink if your e-motors are dead.

[hocking]

I have no idea why I am experiencing, but I am experiencing negative bouyancy when I dive to 160 meters and then go to silent running. When I am down around 150 to 160 meters and running at silent running (less than 2 knots), I start sinking deeper. One time I had sunk all the way to 185 meters before I noticed.

What is causing this?

[Tigrone]

I am sorry Dear Kapt. Lehmann, but I too am having some trouble with the rising. It is not the positive boyancy itself but that the rise seems very rapid at periscope depth. I find my boat goes from 15 to 10 meters so quickly that I do not have time to plot or setup intercepts and shots without attending to it. I have to increase speed a knot and dive several times a minute to keep my tower from being exposed. In a couple of single missions it seemed like I was starting the mission with my conning tower exposed within sight of the escorts. Is there a way to slow the rate of rise?

[Kpt. Lehmann]

I am sorry Dear Kapt. Lehmann, but I too am having some trouble with the rising. It is not the positive boyancy itself but that the rise seems very rapid at periscope depth. I find my boat goes from 15 to 10 meters so quickly that I do not have time to plot or setup intercepts and shots without attending to it. I have to increase speed a knot and dive several times a minute to keep my tower from being exposed. In a couple of single missions it seemed like I was starting the mission with my conning tower exposed within sight of the escorts. Is there a way to slow the rate of rise?

Unfortunately I cannot slow the rate of ascension without nullifying the positive bouyancy. Some boats have different rates of ascension... IIRC the VIIB is the fastest. The problem is that I've got them on the razor's edge of positive vs neutral bouyancy where the code is concerned.

After I get to feeling better I'll post a modlet to remove the positive bouyancy for those that are interested. It will likely be a few days even though it is a simple matter.

(ATM I'm just catching up on latest news and email. I've injured my back this week... and have developed a fever now so I'll be going back to bed in a few minutes... poor me LOL. :doh: Maybe its a brain tumor.:huh: )

[Hartmann]

Good health Kpt Lehmann. ;)

[svenks]

Hi Kapt,

Take your time and get well first!:up:
This can surely wait.

BRGDS
Sven

[Samwolf]

(ATM I'm just catching up on latest news and email. I've injured my back this week... and have developed a fever now so I'll be going back to bed in a few minutes... poor me LOL. :doh: Maybe its a brain tumor.:huh: )

http://fraser.typepad.com/photos/uncategorized/moviepic010_1.jpg

It's not a toooomer!!

[Kpt. Lehmann]

(ATM I'm just catching up on latest news and email. I've injured my back this week... and have developed a fever now so I'll be going back to bed in a few minutes... poor me LOL. :doh: Maybe its a brain tumor.:huh: )

http://fraser.typepad.com/photos/uncategorized/moviepic010_1.jpg

It's not a toooomer!!

LOL...:rotfl: :rotfl: :rotfl: I'll be back.

[Paajtor]

If I blow the ballasts with helium will my sub rise out of the water and into the air? ;)
What a waste!
Don't blow ballast with helium....blow it into your sub, and the entire crew will start talking really funny. :lol:

Back on topic: Lehmann, please keep things as they are.
It's not perfect, but it's the best we can get in SH3.
I don't mind, having to micro-manage depth at SR.
And I spend most my time surfaced, so I'm glad to have a boat that behaves nicely on the waves. :)

[Gavilan]

Hi gents, any updates on this mini-mod to revert to neutral bouyancy?

Thanks,

Gav

[melnibonian]

I can understand that having the boat rising causes problems but so far for me it isn't so terrible. I've just changed a bit my tactics. In my opinion it's all a matter of getting used to.

[Hartmann]

I found that at periscope depth and 2 knts is always 3-4 meters above requested depth, and setting depth to 16 meters seems that stabilize itself at 13 meters after some time.

the only problem is when the boat starts a mission near enemy warships at very shallow deep, for example 12 meters and you need increase the speed for go to 14 meters with risk of being detected.

perhaps changing periscope depth settings could help :hmm: , or set more depth in missions, with positive buoancy is easier raise the boat.

[johnno74]

I have no idea why I am experiencing, but I am experiencing negative bouyancy when I dive to 160 meters and then go to silent running. When I am down around 150 to 160 meters and running at silent running (less than 2 knots), I start sinking deeper. One time I had sunk all the way to 185 meters before I noticed.

What is causing this?

Interesting - When I heard about the positive boyancy thing I was wondering just how accurate the modelling is, and if just this would happen.

I'm a recreational scuba diver, and maintaining your depth isn't easy - if you have positive boyancy, you rise a bit, and then the air in your lungs and your BCD expands because of less pressure, so you have a bit of extra boyancy... which makes you rise even more. If you aren't paying attention you'll start accelerating towards the surface, or sinking - fine on a flat bottom, but when you are diving along the edge of a cliff, NOT a good idea. you have to keep a VERY close eye on your depth.

Anyway, this is why maintaining trim is so tricky. If it was SH3/GWX was *truely* accurate it would be all but impossible to hold depth anywhere but on the surface or on the bottom without some foward motion.

But the boyancy of your sub SHOULD change with depth... and it should be harder to maintain trim at shalow depths - 10m is 2 bar (2x atmospheric pressure) so this means the air in your ballast tanks only gives you half the boyancy it did at the surface... after sinking only 10m. 90m is 10 bar and 100m is 11 bar, so in 10m at that depth your boyancy only should change 1/10th. It looks like this is modelled to some degree in SH3.

Yes, the whole positive boyancy thing is a pain when stationary at PD, but I think its probably still easier than it was in than RL. Overall I'd rather have things the way they are with GWX. Kudos to Kpt. Lehmann for everything, who ever thought SH3 was capable of this?! :up:

(and kudos to ssi/ubisoft for making the game so moddable :yep:)

[Bill Nichols]

I have no idea why I am experiencing, but I am experiencing negative bouyancy when I dive to 160 meters and then go to silent running. When I am down around 150 to 160 meters and running at silent running (less than 2 knots), I start sinking deeper. One time I had sunk all the way to 185 meters before I noticed.

What is causing this?

Interesting - When I heard about the positive boyancy thing I was wondering just how accurate the modelling is, and if just this would happen.

I'm a recreational scuba diver, and maintaining your depth isn't easy - if you have positive boyancy, you rise a bit, and then the air in your lungs and your BCD expands because of less pressure, so you have a bit of extra boyancy... which makes you rise even more. If you aren't paying attention you'll start accelerating towards the surface, or sinking - fine on a flat bottom, but when you are diving along the edge of a cliff, NOT a good idea. you have to keep a VERY close eye on your depth.

Anyway, this is why maintaining trim is so tricky. If it was SH3/GWX was *truely* accurate it would be all but impossible to hold depth anywhere but on the surface or on the bottom without some foward motion.

But the boyancy of your sub SHOULD change with depth... and it should be harder to maintain trim at shalow depths - 10m is 2 bar (2x atmospheric pressure) so this means the air in your ballast tanks only gives you half the boyancy it did at the surface... after sinking only 10m. 90m is 10 bar and 100m is 11 bar, so in 10m at that depth your boyancy only should change 1/10th. It looks like this is modelled to some degree in SH3.


Of course, when the boat is submerged the ballast tanks are filled with water, so the effect on buoyancy of changing depth has nothing to do with the ballast tanks. What is actually happening is that the pressure hull compresses a small amount the deeper one goes. The compression on the hull means that less water is displaced, thus buoyancy decreases the deeper one goes. Submariners compensate for this by pumping water out of the boat's variable trim tanks when going to a deeper depth. Everything works in reverse when going back up.

This is mentioned in Lothar-Gunther Buchheim's novel The Boat(p. 66):

"The next command startles me. The Chief orders flooding in the [trim] tanks, although the boat is meant to rise.... The order to flood seems nonsensical. I have to think hard before I remember: if we rise, the boat expands because the pressure on it decreases, hence we lose specific gravity; and that must be equalized so we don't shoot up too fast."

There is also an excellent description of the various factors that affect submarine trim on pages 74-76.

:know:

[johnno74]

Of course, when the boat is submerged the ballast tanks are filled with water, so the effect on buoyancy of changing depth has nothing to do with the ballast tanks

Hmm my understanding was the ballast tanks are only PARTIALLY filled with water.
The top of the tanks still contained enough air to give a bit of boyancy, and the bottom of the tanks is open to the sea. To "flood the tanks" some of the air is let out of the top of the tanks, water flows in from the bottom, and you sink... To "blow the tanks" and rise compressed air is pumped into the top of the tanks, displacing the water out the bottom.

If the balast tanks were sealed then they would have to be made strong enough to withstand the water pressure when at depth (unless totally filled) - but by having them vented at the bottom the pressure equalizes - the air inside is compressed, and so takes up less volume, reducing the boyancy it gives. This means they can be located outside the inner pressure hull, saving valuable room...

I've heard of a sub that was tipped right over (by collision or something, sorry can't remember where I read the story) and the air in the ballast tanks escaped out of the vents on the bottom of the tank when they rolled over - instant crash dive. It would be quite important to blow tanks ASAP in this situation :yep:

Of course, there are many others here who know more about submarines than me so please correct me if my understanding is wrong...

[demowhc]

I have a strange issue where the uboat never reaches the depth I order it to. If I order to dive to 20 meters it will dive to about 17. If I order to dive to 30 meters it will dive to 28. The dive planes always look like they are pointed down but the boat will continue to run 3-4 meters shallower than ordered. If I want 20 meters I usually have to order to dive to 23-24 meters. This usually happens when running at 1/3 speed. Is this a new GWX feature? I'm never running silent running when I am doing these manuevers.


Im getting the same thing so now i always set the depth about 2 or 3 meters deeper than i want, and when i go to periscope depth I always have to drop it another meter or 2 as my bridge is sticking out of the water :S

I have also found the same thing with torpedos, i have to set them to around 3 meters or they go straight underneath even the biggest ships! I thought it was because i am using SH3 commander to set wave heights and that was somehow effecting it...

say i set the wave heights to 1.5x im guessing that it is adding to the max hieght of the wave aswell as the max drop between the waves (best i can explain it >.< hope u understand haha). so really you are at the correct depth but due to the waves extra height at thier peak and th extra lowness between the waves it appears that u are sticking out of the water, although i cant explain why the depth guage shows im at 8 when iv set it to periscope depth... btw only have GWX installed

[Bill Nichols]

Of course, when the boat is submerged the ballast tanks are filled with water, so the effect on buoyancy of changing depth has nothing to do with the ballast tanks

Hmm my understanding was the ballast tanks are only PARTIALLY filled with water.
The top of the tanks still contained enough air to give a bit of boyancy, and the bottom of the tanks is open to the sea. To "flood the tanks" some of the air is let out of the top of the tanks, water flows in from the bottom, and you sink... To "blow the tanks" and rise compressed air is pumped into the top of the tanks, displacing the water out the bottom.

If the balast tanks were sealed then they would have to be made strong enough to withstand the water pressure when at depth (unless totally filled) - but by having them vented at the bottom the pressure equalizes - the air inside is compressed, and so takes up less volume, reducing the boyancy it gives. This means they can be located outside the inner pressure hull, saving valuable room...

I've heard of a sub that was tipped right over (by collision or something, sorry can't remember where I read the story) and the air in the ballast tanks escaped out of the vents on the bottom of the tank when they rolled over - instant crash dive. It would be quite important to blow tanks ASAP in this situation :yep:

Of course, there are many others here who know more about submarines than me so please correct me if my understanding is wrong...

Your understanding is wrong. When submerged, the ballast tanks are completely full of water. The vents on the top of the tanks are shut, but the floods on the bottom are open, thus ensuring equal water pressure inside and outside of the ballast tanks.

Submariners go to a lot of trouble to ensure there is no air trapped in the ballast tanks when submerged. When the boat dives, the vents are opened and remain open until the sub is well underwater. After reaching the ordered depth, the vents are cycled open and shut to let out any air that didn't go out during the dive. If the sub remains submerged for any length of time, the vents are cycled open and shut periodically in case any air has leaked into the ballast tanks from the sub's high-pressure air system. The reason for doing all of this is precisely to avoid the buoyancy problems you described should there be a bubble of air in the ballast tanks.

Trust me, I know of what I speak. :know:

http://www.subguru.com/nautilus/subqual.jpg
:lurk:

[panthercules]

Trust me, I know of what I speak. :know:

http://www.subguru.com/nautilus/subqual.jpg
:lurk:

Very cool - so you must have been one of the last crew to serve on this historic vessel before she was decommissioned - were you aboard for her last cruise from Groton to Mare Island that ended that May? Did she go through the Canal or take the short cut under the Pole again? :D

[Deamon]

What is actually happening is that the pressure hull compresses a small amount the deeper one goes.

I'm woundering how much do it compress vs. depth ? :hmm:

I'm looking for a formula for simulation purpuoses.

[Deamon]

Hmm my understanding was the ballast tanks are only PARTIALLY filled with water.
Partialy filled are only the compensating and trimm tanks, not the buoyancy tanks!

When it would be as you described it, any submarine would be uncontrolable!

[Bill Nichols]

Very cool - so you must have been one of the last crew to serve on this historic vessel before she was decommissioned - were you aboard for her last cruise from Groton to Mare Island that ended that May? Did she go through the Canal or take the short cut under the Pole again? :D

Yep, I was on the final crew. We took her through the canal. I'm proud to say that I was Officer of the Deck for her last dive after departing San Diego en route to Mare Island.

We discussed going across the pole, but for technical reasons decided that would not have been prudent.

[Bill Nichols]

What is actually happening is that the pressure hull compresses a small amount the deeper one goes.

I'm woundering how much do it compress vs. depth ? :hmm:

I'm looking for a formula for simulation purpuoses.

The exact number depends on the size of the hull and how strong it is. A rough value is given in the book, "Concepts in Submarine Design". In Section 3.12 it says, "The buoyancy loss at full diving depth can be reckoned in tens of tonnes in a submarine of 2000 to 3000 tonnes submerged displacement."

The book "Theory of Submarine Design" (by Kormilitsin and Khalizev) in Section 7.4 gives an equation for submarine buoyancy variations due to hydrological effects, and typical values for the input parameters. It's too much for me to quote here, if you want more send me an e-mail.


For simulation purposes, you'll also need to consider the effect of water density variations at different depths (caused mostly by temperature changes, with a small contribution from hydrostatic pressure). Variations in salinity can also be important, although salinity tends to be mostly constant across most of the ocean.

[AS]

Now that we have a real submariner around, I´d love to know something about the "real thing"! Maybe you feel like answering some of my questions, I´d appreciate it very much!

1. I often wonder what it is like to dive and run submerged. Do you have a "sense of being under water" or is it rather a matter of gauges telling you how deep you are? In simple terms: is a submariner AWARE of travelling under water (e.g. creaking sounds, water dripping etc.?)

2. Is there any light switching for day and night to go with the normal day/night shift or is it just always bright light everywhere?

3. Would you say that SH3 U-Boat performances are somewhat realistic with regard to "depth changing time", turning, acceleration?

4. Finally back to our topic: do you think a real sub would surface after a while (positive buoncy) or go deep if all engines were stopped? (I know today they have hovering automatics, but let´s imagine we are in WW2, the batteries are empty: what would the U-Boat do?)

Cheers, AS

[Deamon]

The exact number depends on the size of the hull and how strong it is.
Can the strength be concluded from the subs crush depth ?

The book "Theory of Submarine Design" (by Kormilitsin and Khalizev) in Section 7.4 gives an equation for submarine buoyancy variations due to hydrological effects, and typical values for the input parameters. It's too much for me to quote here, if you want more send me an e-mail.
Haven't seen your mail somewhere. Will PM you instead.

For simulation purposes, you'll also need to consider the effect of water density variations at different depths (caused mostly by temperature changes, with a small contribution from hydrostatic pressure). Yes I know. Hydrostatic pressure ? You mean from currents, like in gibralter wher you would bounce of when you dive to a curtain depth ?

Variations in salinity can also be important, although salinity tends to be mostly constant across most of the ocean. I think there are also fluctuations due to rain and sun. Also where my sim takes place is the edge where very different salinity levels meet each other. Also through currents there can be salinity layers of a very different concentration, as i have red from some accounts.

[Bill Nichols]

1. The exact number depends on the size of the hull and how strong it is.
Can the strength be concluded from the subs crush depth ?

2. The book "Theory of Submarine Design" (by Kormilitsin and Khalizev) in Section 7.4 gives an equation for submarine buoyancy variations due to hydrological effects, and typical values for the input parameters. It's too much for me to quote here, if you want more send me an e-mail.
Haven't seen your mail somewhere. Will PM you instead.

3. For simulation purposes, you'll also need to consider the effect of water density variations at different depths (caused mostly by temperature changes, with a small contribution from hydrostatic pressure). Yes I know. Hydrostatic pressure ? You mean from currents, like in gibralter wher you would bounce of when you dive to a curtain depth ?

4. Variations in salinity can also be important, although salinity tends to be mostly constant across most of the ocean. I think there are also fluctuations due to rain and sun. Also where my sim takes place is the edge where very different salinity levels meet each other. Also through currents there can be salinity layers of a very different concentration, as i have red from some accounts.

1) Crush depth is certainly an indication of how strong the hull is, but that's not enough for estimating buoyancy variation with depth. The latter depends on how much the hull compresses when sea pressure increases. That depends on what the hull is made of, the thickness of the pressure hull, etc.

2) BillNichols a t Subguru.com

3) Hydrostatic pressure is pressure at a given depth. For seawater, that amounts to about 44psi for every 100ft depth increase.

4) Yeah, those things (rain, salinity variations e.g. freshwater to seawater, etc.) can affect water density and thus buoyancy.

[Bill Nichols]

Now that we have a real submariner around, I´d love to know something about the "real thing"! Maybe you feel like answering some of my questions, I´d appreciate it very much!

1. I often wonder what it is like to dive and run submerged. Do you have a "sense of being under water" or is it rather a matter of gauges telling you how deep you are? In simple terms: is a submariner AWARE of travelling under water (e.g. creaking sounds, water dripping etc.?)

2. Is there any light switching for day and night to go with the normal day/night shift or is it just always bright light everywhere?

3. Would you say that SH3 U-Boat performances are somewhat realistic with regard to "depth changing time", turning, acceleration?

4. Finally back to our topic: do you think a real sub would surface after a while (positive buoncy) or go deep if all engines were stopped? (I know today they have hovering automatics, but let´s imagine we are in WW2, the batteries are empty: what would the U-Boat do?)

Cheers, AS

1) There's no real indication that one is underwater, unless you're near the surface and can feel wave action. I compare the feeling one gets in a submarine to being in a train with no windows. You know you are moving (can feel vibrations, etc.) but you don't know anything about what is outside.

2) My experience (US nuclear subs) is that most areas are continually lit. Exceptions are the berthing areas (lights always off, unless on for cleaning) and the control room/attack center. In the latter, lights are either off or rigged-for-red during evening hours so that the OOD's night vision will not be impaired should the sub need to surface in an emergency.

3) I'm happy with SH3's representation. I'm not so happy about the 'positive buoyancy' mod, though. :-? My feeling about that is: As CO, even if I keep the boat at a slight positive buoyancy, I expect my crew to keep the depth I have ordered. If I order periscope depth, I expect the boat to go to periscope depth, not any shallower. If I go to all stop, I expect the crew to flood the variable tanks as necessary to keep the sub from bobbing to the surface.

4) Some CO's like to keep the boat as close to neutral buoyancy as possible, others prefer a slight positive buoyancy. If the boat is positively buoyant, then stopping the engines will cause the sub, under most conditions, to rise to the surface. Similarly, if the boat is negatively buoyant, it will drop to the bottom. It is nearly impossible to always keep the sub at exactly neutral buoyancy, so if one stops the engines it will generally either go up or down if nothing else is done. By pumping water into or out of the variable ballast tanks, the crew can adjust the buoyancy to 'hover' at a given depth. As you mentioned, many modern subs have an automatic system for hovering.

:arrgh!:

[Deamon]

As you mentioned, many modern subs have an automatic system for hovering. The type 212 have even an autopilot. When you are on the surface for example, you just need to say bring me to 20 meters and nothing more need to be done. :arrgh!::arrgh!::arrgh!:

[svenks]

I'm not so happy about the 'positive buoyancy' mod, though. :-? My feeling about that is: As CO, even if I keep the boat at a slight positive buoyancy, I expect my crew to keep the depth I have ordered. If I order periscope depth, I expect the boat to go to periscope depth, not any shallower. If I go to all stop, I expect the crew to flood the variable tanks as necessary to keep the sub from bobbing to the surface.


My point exactly! Unfortunately as Kapt Lehman points out, there is no trim in SH3.

But that being the case, I've come to the conclusion that Neutral Buoyance is probably the best way to go, even if it is a compromise. So that's where I'll cast my vote.

And speaking of the good Kaptain: How are you doing?

BRGDS
Sven

[Pirate]

I also vote for having the option of nutral bouyancy. The famous modlet that didn't came out :) lol

[AS]

@ Bill Nichols: thank you very much indeed!:up:

Cheers, AS

[Sailor Steve]

It is nearly impossible to always keep the sub at exactly neutral buoyancy, so if one stops the engines it will generally either go up or down if nothing else is done. By pumping water into or out of the variable ballast tanks, the crew can adjust the buoyancy to 'hover' at a given depth. As you mentioned, many modern subs have an automatic system for hovering.

:arrgh!:
I think that was the idea of both the "positive bouyancy" in GWX and the "negative effect" of the Anti-Hummingbird Mod; to make it inconvenient to stop underwater. It would be nice if the future could find some way to randomly have all three-positive, negative and neutral.

On the other hand, all this is a lot of work to force gamers to do something they could always do for themselves, i.e. not stop while submerged.

[FIREWALL]

I myself like pos boyance. Sorry for bad spelling. Was in Scarpa Flow
9-26-39 to recreat G.P. famous sinking of Royal Oak. Sat on bottom
with no damage on silent running, stop for two hrs real time. " had to
do a couple a things around the house for the Admrl.:lol: " hideing out
from two DD's.

But it's not a bad idea to do a small mod to remove it .

BTW Kpt Hope your feeling better.:up:

[Albrecht Von Hesse]

Now I'll admit having NO clue how bouyancy is coded in the game. However, I've an idea (and because I've no clue I've also no idea if this is possible:oops: )

Is there any way that, any time you bring your boat below 2 knots submerged the game randomly selects either positive, neutral or negative bouyancy, and whenever surfaced always positively bouyant? (As my understanding with GWX is that positive bouyancy was needed for the boat handling performance)

[Kpt. Lehmann]

I myself like pos boyance. Sorry for bad spelling. Was in Scarpa Flow
9-26-39 to recreat G.P. famous sinking of Royal Oak. Sat on bottom
with no damage on silent running, stop for two hrs real time. " had to
do a couple a things around the house for the Admrl.:lol: " hideing out
from two DD's.

But it's not a bad idea to do a small mod to remove it .

BTW Kpt Hope your feeling better.:up:

Sorry for my absence all.

The bad weather has made my real life job absolute hell. I've been in work-eat-sleep mode for several days. On my time off I've been too tired to even turn on my PC.

I'll make a small JGSME mod removing the positive bouyancy this coming weekend. It will not be a part of the January 31st update however. It will be made available completely separate from GWX as removing the positive bouyancy removes other intended effects.

[Gavilan]

The bad weather has made my real life job absolute hell. I've been in work-eat-sleep mode for several days. On my time off I've been too tired to even turn on my PC.

I'll make a small JGSME mod removing the positive bouyancy this coming weekend. It will not be a part of the January 31st update however. It will be made available completely separate from GWX as removing the positive bouyancy removes other intended effects.

Sorry to hear the weather & work is taking it's toll. Hope things improve for you.

As for the JGSME mod, I think that's the best solution. Then people can decide to use the mod or not depending on preference. I'm certainly not an advanced GWX player so would appreciate the option until I improve and then I can remove the mod if I feel the need.

Thanks for keeping us updated.

Gav.

[Kpt. Lehmann]

As promised:

http://www.subsim.com/radioroom/showthread.php?t=104229

[GT182]

Bill, I've been on the Nautilus in Groton, she's one of the best and a treat to go thru. A bit cramped tho with all the glass they put in her. I wear my SSN 571 cover all the time too. ;) My ex son-in-law was stationed at Groton and the USS Annapolis was his first TOD. I have a friend that lives in Ft. Covington NY that was also at Groton... first name Walter. Can't remember his last name off hand but maybe his first name will ring a bell.

BTW, have you ever had the chance to go back and give her a kiss? She sure is special.