RUb Depth Charges - a strange incident.

[jason210]

I've been playing RUb all day. I think I can live with the gun - it just takes some getting used to after being spoiled with the default gun for 6 months.

Something that I find hard to accept are the depth charges. I was 108 m underwater, and on the surface was destroyer. In the default SHIII, I would expect to hear a report that depth charges were in the water, but this was not reported in RUb. Ok, I can live with that.

Suddenly and unxepctedly, I heard some depth charges going off. They weren't close, but the sub was badly damaged. I had hull integrity turned on (via SHIII commander) and this remained at 100%, but the rear batteries were destroyed, the main pump destroyed, and most of the rest of the equipment was damaged.Oh, I forgot to say, my radio operator was killed, and I had flooding in several compartments.

I was sinking so I blew the ballast tanks twice. This slowed the sinking down. I managed to get all the water out, and started to come up. I didn't want to break the surface of course, so when I got to 40m I ordered periscope depth. By this time I had repaired everything that could be repaired. As the sub leveled out periscope depth, it began to sink again! I re-ordered periscope depth and we were making 2 kts, so there should have been enough speed for the hydroplanes to keep the depth - but not so. It continued to sink. There were no leaks and there was no water in any compartments. At 47 metres I blew the ballast again and started coming up again. Again, as I neared the surface I ordered periscope depth. The destroyer was still up there, and I did not want to break the surface.

It levelled out at periscope depth, and I raised the periscope and caught a brief glimpse of the Destroyer before the periscope went under...I was sinking again! This time I didn't stop sinking....

I was in a type VIIB and it crushed at 320m.

Three things here. First, the sounds of the explosions did not seem loud enough to have caused all that damage. They were quiet. The damage seemed to happen without any drama. This can't be explained away as unimportant ear candy - the sound and damage have to go together to form the immersive experience.

Second, why was I unable to maintain depth?

Third, why did my radio operator die?

[Beery]

I've been playing RUb all day. I think I can live with the gun - it just takes some getting used to after being spoiled with the default gun for 6 months.

Something that I find hard to accept are the depth charges. I was 108 m underwater, and on the surface was destroyer. In the default SHIII, I would expect to hear a report that depth charges were in the water, but this was not reported in RUb. Ok, I can live with that.

Nothing has been changed in terms of depth charge reporting. The crew won't report depth charges if they don't hear them. If the DCs drop behind the sub the engine noise will cover them up. Also, if the hydrophone guy is tired or unqualified he'll do a worse job.

Suddenly and unxepctedly, I heard some depth charges going off. They weren't close, but the sub was badly damaged. I had hull integrity turned on (via SHIII commander) and this remained at 100%, but the rear batteries were destroyed, the main pump destroyed, and most of the rest of the equipment was damaged.Oh, I forgot to say, my radio operator was killed, and I had flooding in several compartments.

I was sinking so I blew the ballast tanks twice. This slowed the sinking down. I managed to get all the water out, and started to come up. I didn't want to break the surface of course, so when I got to 40m I ordered periscope depth. By this time I had repaired everything that could be repaired. As the sub leveled out periscope depth, it began to sink again! I re-ordered periscope depth and we were making 2 kts, so there should have been enough speed for the hydroplanes to keep the depth - but not so. It continued to sink. There were no leaks and there was no water in any compartments. At 47 metres I blew the ballast again and started coming up again. Again, as I neared the surface I ordered periscope depth. The destroyer was still up there, and I did not want to break the surface.

It levelled out at periscope depth, and I raised the periscope and caught a brief glimpse of the Destroyer before the periscope went under...I was sinking again! This time I didn't stop sinking....

I was in a type VIIB and it crushed at 320m.

Sounds like an exciting and nail-biting patrol. Pity it ended in death. The next version of SH3 Commander includes a 'Surrender' option. You will have the ability to surrender your boat if you're willing to let discretion be the better part of valour.

Three things here. First, the sounds of the explosions did not seem loud enough to have caused all that damage. They were quiet. The damage seemed to happen without any drama. This can't be explained away as unimportant ear candy - the sound and damage have to go together to form the immersive experience.

The depth charge explosion sounds are unchanged from the standard SH3 sounds. This may be a bug in the standard game, or it may be that the DCs exploded at the rear of your boat (which goes along with the fact that you didn't hear them in the water, although it doesn't explain the amount of damage throughout the boat). RUb does indeed make depth charges have more impact on the interior equipment. It makes damage less immediately deadly. One thing to note is that DCs in RUb are substantially LESS damaging than in standard SH3.

Second, why was I unable to maintain depth?

The flooding in RUb has a much greater impact on your ability to stay buoyant than in the standard game. What happened was that you blew ballast, twice, but the boat was still flooding. Maybe you had the flooding somewhat under control, but when it came time to blow ballast a third time there was probably not enough pressure in the ballast tanks to surface the boat. When you tried to surface by using your dive planes, either they were damaged, or your batteries were flooded, or your engines were damaged, or perhaps your boat had simply taken on too much water. Any one of these would have caused your attempt to fail.

Third, why did my radio operator die?

I've no idea. When SH3 calculates damage I think it assigns it based on the proximity of the compartment to the blast. If the damage is too much for a man in that compartment he will die. Maybe he was thrown off balance by the blast, or maybe he had some other accident.

[jason210]

Thanks. It was a good patrol but the first time I came to periscope depth I had 25% compressed air left, so I hadn't run out when I sank the first time.

I guess, like the gun, I'll get used to this new interior damage, but it seems a bit strong when major equipment is actually destroyed. As you said, it's a pity it ended in depth - but there was nothing I could do. If I'd surfaced that would have been the end too.

[Kissaki]

But didn't you say there was no water in any compartments? The u-boat commanders on shore are worried... :(

[Beery]

But didn't you say there was no water in any compartments? The u-boat commanders on shore are worried... :(

True, he did say there was no water in the compartments. I missed that one. However, if he was already down to 25% compressed air when he sank the first time, then he must have had very little after he blew ballast the second time. If he had no compressed air (or too little) and perhaps no propulsion (or a damaged system that killed the propulsion), he would sink.

[BipBip]

I have another question about this accident :

Were your depth planes (bow or aft) damaged ?
Did you put power to help your sub in its rising ?

[Kissaki]

But didn't you say there was no water in any compartments? The u-boat commanders on shore are worried... :(

True, he did say there was no water in the compartments. I missed that one. However, if he was already down to 25% compressed air when he sank the first time, then he must have had very little after he blew ballast the second time. If he had no compressed air (or too little) and perhaps no propulsion (or a damaged system that killed the propulsion), he would sink.

Well, he had 2 kts. which I would think insufficient - but would a sub sink for lack of compressed air? I'm no technical expert, but if that is indeed the case it looks like I'm going to have to go through some new safety routines and regulations with my crew!

[Beery]

Well, he had 2 kts. which I would think insufficient - but would a sub sink for lack of compressed air? I'm no technical expert, but if that is indeed the case it looks like I'm going to have to go through some new safety routines and regulations with my crew!

I found that (when I was using SH3 version 1.3) if I was running silent at 3 knots, the boat had a tendency to sink. This was with no mods affecting the damage or the buoyancy). I'm not sure what SH3 1.4b does - I haven't noticed that same sinking tendency recently. I think if a U-boat had no propulsion (or too little) and no compressed air it would almost definitely sink. U-boats retain buoyancy by a mixture of ballast and propulsion. If neither is sufficient to maintain neutral buoyancy it will sink. I think the air contained in the boat's crew compartments is not enough, on its own, to surface the boat even if it is at a shallow depth.

[Mr.Fleck]

The tendency to sink is still there in SH3 1.4b (with RUb 144), but it seems to occur very seldom. I experienced it last night. Below 3 knots my sub was sinking. At 4 knots and above I could get higher. My boat was not damaged and the zentrale was at 100% efficiency. I think SH3 does not model the fact that the pumps are not working below 150 meters (at least I think this is the depth). Else the added water weight could explain the sinking.
Does someone know how the "sinking effect" is triggered? The next three times I submerged I experienced no sinking at all (even at 0 knots over 1-2 hours which definitely is not very realistic)

I'm not sure where I read it but as I recall "Schleichfahrt" at 90 rmp (corresponds to aprox. 1 knot) and proper dive plane settings should be sufficient to keep the depth of a Type VII (with neutral buoyancy).

[Jungman]

I notice that below about 200+ meters, the Uboat will sink slowly if not moving forward a small amount of speed. In shallower water, I do not sink at all at zero speed.

In my testing of a new mod, I notice the changes made to floatability and critical floatability could cause bouyance problems not so noticeable. It was changed to get more flooding time.

I stay away from it, what happens is your Uboat is too 'floaty', and then if you happen to get enough physical damage to be below critical floatation (which is reduced almost to zero) you will experience something like that, sink like a rock.

Normally your chance of compartment damage landing in that small spot is very unlucky. Was one of your comparments almost completely destroyed in the red? The color sometimes is not correct with the text due to increase HP made to it.

[Beery]

I just had the exact same experience as Jason210. I kept blowing ballast and stopping at periscope depth. I had some bad damage but the main thing I noticed was that the electric motors weren't working. I was still going along at 2kts, but the motors weren't working. Because of the damage I kept see-sawing up and down, alternately sinking and blowing ballast. Eventually I surfaced and got attacked and sunk. But it felt right. With a badly damaged boat things go wrong very quickly and the boat's trim is what tends to go wrong first.

[Kissaki]

I think if a U-boat had no propulsion (or too little) and no compressed air it would almost definitely sink.

I don't see why the amount of compressed air would affect buoyancy. When one spends compressed air to blow the ballast tanks, it is not replaced by anything heavier. Even air has positive weight, and is certainly heavier than vacuum. Having no compressed air left would therefore make the sub lighter, though not significantly.

[Beery]

I think if a U-boat had no propulsion (or too little) and no compressed air it would almost definitely sink.

I don't see why the amount of compressed air would affect buoyancy. When one spends compressed air to blow the ballast tanks, it is not replaced by anything heavier. Even air has positive weight, and is certainly heavier than vacuum. Having no compressed air left would therefore make the sub lighter, though not significantly.

My point was simply that without any means of giving the sub positive buoyancy it would sink. submerged U-boats, if they are without ballast, are heavier than the water around them.

[Kissaki]

My point was simply that without any means of giving the sub positive buoyancy it would sink. submerged U-boats, if they are without ballast, are heavier than the water around them.

If they are without ballast? Without compressed air, you mean? Because you can't get a sub lighter than having no ballast - and I've been able to surface without blowing ballast tanks and with no propulsion.

[Beery]

My point was simply that without any means of giving the sub positive buoyancy it would sink. submerged U-boats, if they are without ballast, are heavier than the water around them.

If they are without ballast? Without compressed air, you mean? Because you can't get a sub lighter than having no ballast - and I've been able to surface without blowing ballast tanks and with no propulsion.

Yeah, without compressed air is what I mean. You can surface without blowing ballast and without propulsion. As I understand it, it's a very annoying flaw in the simulation.

[Kissaki]

My point was simply that without any means of giving the sub positive buoyancy it would sink. submerged U-boats, if they are without ballast, are heavier than the water around them.

If they are without ballast? Without compressed air, you mean? Because you can't get a sub lighter than having no ballast - and I've been able to surface without blowing ballast tanks and with no propulsion.

Yeah, without compressed air is what I mean. You can surface without blowing ballast and without propulsion. As I understand it, it's a very annoying flaw in the simulation.

The only way I can make sense of this is if the ballast tanks are only "buoyantly" full, and not empty - and with no compressed air to push more water out. The presence of compressed air itself shouldn't do anything for buoyancy, because unless it has negative weight (which it doesn't) it doesn't make the boat lighter. And the uboat displaces the same ammount of water regardless.

[Beery]

The only way I can make sense of this is if the ballast tanks are only "buoyantly" full, and not empty - and with no compressed air to push more water out. The presence of compressed air itself shouldn't do anything for buoyancy, because unless it has negative weight (which it doesn't) it doesn't make the boat lighter. And the uboat displaces the same ammount of water regardless.

I'm no scientist, but I know that if you blow ballast, the boat rises. If you fill the ballast tanks with water the boat will sink. If you have no compressed air and no propulsion the boat will sink. Air is lighter than water, which means that in water it has a 'negative weight' - a tendency to rise to the surface. Fill the volume of a ballast tank with it and the boat will rise because the boat has become lighter than the water around it. It's like a balloon. The balloon itself (the plastic envelope) has a certain weight, but its weight is modified by the gas that you put in it. Put air in it and it will just fall to the ground because you've filled it with ballast. Put helium in it and it rises. But it will only rise if there is enough helium to counteract the weight of the balloon.

If you put a propeller and dive planes on an air filled balloon you can probably get it to rise into the air. If you blow ballast by replacing the air with helium it will also rise. But if your propeller is broken and all your helium is gone, the balloon will sit on the floor, and there will be no way to make it fly.

[Kissaki]

I'm no scientist, but I know that if you blow ballast, the boat rises. If you fill the ballast tanks with water the boat will sink. If you have no compressed air and no propulsion the boat will sink. Air is lighter than water, which means that in water it has a 'negative weight' - a tendency to rise to the surface. Fill the volume of a ballast tank with it and the boat will rise because the boat has become lighter than the water around it. It's like a balloon. The balloon itself (the plastic envelope) has a certain weight, but its weight is modified by the gas that you put in it. Put air in it and it will just fall to the ground because you've filled it with ballast. Put helium in it and it rises. But it will only rise if there is enough helium to counteract the weight of the balloon.

If you put a propeller and dive planes on an air filled balloon you can probably get it to rise into the air. If you blow ballast by replacing the air with helium it will also rise. But if your propeller is broken and all your helium is gone, the balloon will sit on the floor, and there will be no way to make it fly.

But the uboat rises so long as it weighs less than the water it displaces. As long as the ballast tanks are empty enough for the boat to rise, it shouldn't matter how much compressed air you had left. If it did, you have a hard time explaining the following case:

You have no propulsion, and you have just enough compressed air to blow the ballast tank one last time. You do, and the sub rises. After it's done rising, it starts sinking because of lack of compressed air.

Question is, if the lack of compressed air makes it sink, why did it rise in the first place?


Now, a cannister of compressed air is a heavy thing. Let's say it's a tiny one of about 10 lbs. both full and empty. If you put one on the boat, that's going to make the boat 10 lbs. heavier, whether it's full or not.


But tell you the truth, I now feel tempted to build my own type II and find out the hard way. :P

[Beery]

But the uboat rises so long as it weighs less than the water it displaces. As long as the ballast tanks are empty enough for the boat to rise, it shouldn't matter how much compressed air you had left. If it did, you have a hard time explaining the following case:

You have no propulsion, and you have just enough compressed air to blow the ballast tank one last time. You do, and the sub rises. After it's done rising, it starts sinking because of lack of compressed air.

Question is, if the lack of compressed air makes it sink, why did it rise in the first place?

That's easy. You have a leak in your ballast tank and compressed air is being replaced with sea water. At first the sea water would be pumped out - just like if you had a leaky balloon filled with air and started filling it with helium, at first it would rise, but after a minute the helium would escape and air would start to enter the leaks. Then the balloon would sink.

Now, a cannister of compressed air is a heavy thing. Let's say it's a tiny one of about 10 lbs. both full and empty. If you put one on the boat, that's going to make the boat 10 lbs. heavier, whether it's full or not.

Yeah, but that 10lbs of compressed air can remove many times its weight in seawater from the boat.

[Kissaki]

That's easy. You have a leak in your ballast tank and compressed air is being replaced with sea water. At first the sea water would be pumped out - just like if you had a leaky balloon filled with air and started filling it with helium, at first it would rise, but after a minute the helium would escape and air would start to enter the leaks. Then the balloon would sink.


I have a leak in my ballast tank? Stempel, grab a monkey wrench and have at it!

Seriously, though, are there not little hatches or such in the ballast tank that open to take in or expell water, and close to maintain buoyancy? Otherwise you'd be constantly using compressed air - even while travelling at the surface.

Yeah, but that 10lbs of compressed air can remove many times its weight in seawater from the boat.

Yes, but now all the seawater is gone. So is the compressed air. We're at the surface, and for the sake of argument the dive planes are located on the conning tower. In fact we're docked, and nobody's minding the sub. Why should it sink?

[Beery]

Seriously, though, are there not little hatches or such in the ballast tank that open to take in or expell water, and close to maintain buoyancy? Otherwise you'd be constantly using compressed air - even while travelling at the surface.

Of course, but if you have a leak, the tank will tend to equalize pressure with whatever the hole leads to. That means seawater if the boat is submerged. You can't plug a leak by opening or closing a hatch. The defining characteristic of a leak is its tendency to leak. :lol:

Yeah, but that 10lbs of compressed air can remove many times its weight in seawater from the boat.

Yes, but now all the seawater is gone. So is the compressed air. We're at the surface, and for the sake of argument the dive planes are located on the conning tower. In fact we're docked, and nobody's minding the sub. Why should it sink?

Who said it was surfaced? You asked me why a boat would rise a bit and then sink. We never talked about surfacing. On the surface it's a different matter entirely because the boat can be kept buoyant by filling the ballast tanks with air from outside using the pumps. You don't need compressed air.

[Beery]

Check it out:

http://www.onr.navy.mil/focus/blowballast/sub/work3.htm

[Jungman]

You can make a submarine rise or sink while at neutral bouyance. Normal and no leaks without using very little air. It is what they do when using flood recovery. It is very slow compared to using compressed air to force water out of the ballast.

Using a high pressure pump, you can pump water inside the submarine interior or ballast area out into the open sea under the pumps high pressure. It will leave a less thin air inside the sub which can be replaced with a little air from the 'low' air supply line if you wish. This small amount of air is just replacing the water that was pumped out of the sub into the ocean outside under pressure.

This does not work well if you are realy deep since the outside pressure is so high, you cannot pump againts it -thus in the old days that is why they would say subs had a tendency to sink if you did not keep it moving via the dive planes. It was impossible back then to pump against extreme high pressure at very deep levels.

That demo is very basic and a submarine can rise and fall with very little or no air usage very slowly. Only if it is an emergency need it expell it high pressure air. But they did use a small amount every time they moved up/ down back then using the pumps due to engineering reality.

Example, take a rubber compressed can with a compressed spring inside it. Make it so it just barely floats neutral. If you release the spring under water, the expanded spring will make the rubber can bigger displacing water weight around it and it will rise to the surface using no air. Of course the air pressure inside the can is droped some due to the air filling in where the water was, and that is were the small amount of low pressure air usage comes in.

Now a submarine has no rubber hull to expand. It is solid, so they use a high pressure water pump and valve to force the water from the ballast tank or water flooded inside the sub to the outside ocean. It is slow and will not work if too deep due to engineering limitations.

I had a great link on how the military used this in real life to minimize compressed air usage. Modern diesel submarines under normal operation and not damaged, could rise and sink without expelling air to a great degree slowly using this trick. It is like a expandable badder in a fish but using a pump instead.

http://www.geocities.com/gwmccue/Systems/Ballast_System.html

Anothe point I forgot but is modelled in the game, under high dep water pressure the boats hull is compresed some, making it displace less water, and thus tend to sink. Shoot a torpedo out and you lose weight and you tend to rise. Ther are auxillary tanks to help control over this stuff. It gets to be quite a bit of stuff to handle. They do remakr it is imposible to achieve perfect neutral bouyance. It is a saddle point, you will either rise or sink very slowly. So many subs moved alittle to keep at neutral depth.