[REL] Depth keeping problem fixed

[Obelix]

Originally Posted by Magnum

Using stock settings I can dive and keep depth without using the engines down to 160m. Between 160 and 180m I need at least 1-2kts to keep the sub floating, under 200m I need 4 and at 250 and bellow I need full power to level up. I consider this a very normal situation for a sub in the 38-45 time period. We are not talking about nuclear subs here and the color markers on the depth dial are for a reason.

No movement can not keep the boat at a given depth, even on modern boats. The thing that is impossible to perfectly balance the boat for holding at the desired depth without motion. The boat will tend either to surface or the bottom. Therefore, to keep the depth of the boat had to be at least a minimum speed that seaplanes could keep a boat at depth.
Therefore, keeping the depth of no motion, I believe than the fantastic and the game it's always annoyed me. How, indeed, falling through to a depth at low speed.

[Vanilla]

Originally Posted by Obelix

No movement can not keep the boat at a given depth, even on modern boats. The thing that is impossible to perfectly balance the boat for holding at the desired depth without motion. The boat will tend either to surface or the bottom. Therefore, to keep the depth of the boat had to be at least a minimum speed that seaplanes could keep a boat at depth.
Therefore, keeping the depth of no motion, I believe than the fantastic and the game it's always annoyed me. How, indeed, falling through to a depth at low speed.

Now imagine yourself a real kaleun in a sub at 200m depth with a couple of DDs overhead. You are trying to be as quite as possible but notice that your submarine is constantly falling down to dangerous depth unless you keep 5 knots of speed. Do you think a kaleun would not 'politely ask' his LI to dump 50-100l of ballast so he can keep silent running? I would defenitely do rather than be forced to choose between dying of depth because of sinking or DCs because of giving out my position. LI and trim system are there for a reason.
The bouyancy is obviously tricky to control but not impossible. And there is more than enough boyancy in all the tanks to keep level or rise at any depth - remember that the tanks volume (read bouyancy) is almost constant (unless damaged or crushed) with changing depth. And 1-2 knots is pretty much enough for horizontal planes to be effective in precise depth control.

Given all that I would agree that it is realistic if we would see some vertical speed, but random and dependent on depth, speed and damage, i.e. -15m after 10 minutes and +17 minutes after another 10 minutes at 100m depth at dead stop. Not constant -1m/s sinking we see now in vanilla - I would kill my LI I guess, if I'd seen that in RL.
Moreover I would love to see some compressed air consumption when submerged to simulate trimming, ideally dependent on speed, depth and of course damage. And that would be awesome to see some radical drop down some 40-50m down with some generous compressed air dump when a tank is crushed to simulate neutral bouyancy disruption and consecutive stabilising efforts through ballast dumping.

[Obelix]

Originally Posted by Vanilla

Now imagine yourself a real kaleun in a sub at 200m depth with a couple of DDs overhead. You are trying to be as quite as possible but notice that your submarine is constantly falling down to dangerous depth unless you keep 5 knots of speed. Do you think a kaleun would not 'politely ask' his LI to dump 50-100l of ballast so he can keep silent running? I would defenitely do rather than be forced to choose between dying of depth because of sinking or DCs because of giving out my position. LI and trim system are there for a reason.
The bouyancy is obviously tricky to control but not impossible. And there is more than enough boyancy in all the tanks to keep level or rise at any depth - remember that the tanks volume (read bouyancy) is almost constant (unless damaged or crushed) with changing depth. And 1-2 knots is pretty much enough for horizontal planes to be effective in precise depth control.

Given all that I would agree that it is realistic if we would see some vertical speed, but random and dependent on depth, speed and damage, i.e. -15m after 10 minutes and +17 minutes after another 10 minutes at 100m depth at dead stop. Not constant -1m/s sinking we see now in vanilla - I would kill my LI I guess, if I'd seen that in RL.
Moreover I would love to see some compressed air consumption when submerged to simulate trimming, ideally dependent on speed, depth and of course damage. And that would be awesome to see some radical drop down some 40-50m down with some generous compressed air dump when a tank is crushed to simulate neutral bouyancy disruption and consecutive stabilising efforts through ballast dumping.

All true, but I talked about that at speed 0 knots to keep the boat at a given depth is not possible. Will be a constant yaw in depth. The boat begins to sink - pump water tends to surface - fill the ballast. And this game (blowing ballast-ballasting) is constant. Another thing that we have a speed of 1-2 knots, it should already allow us to control the depth of the minimum consumption of compressed air.

[Stormfly]

Originally Posted by Obelix

All true, but I talked about that at speed 0 knots to keep the boat at a given depth is not possible. Will be a constant yaw in depth. The boat begins to sink - pump water tends to surface - fill the ballast. And this game (blowing ballast-ballasting) is constant. Another thing that we have a speed of 1-2 knots, it should already allow us to control the depth of the minimum consumption of compressed air.

it would be good to know what force whas used to press water out of the boat using the regulation cells, also which maximum dept was allowed because pressforce have to be stronger then outside water pressure.

[Vanilla]

Originally Posted by Stormfly

it would be good to know what force whas used to press water out of the boat using the regulation cells, also which maximum dept was allowed because pressforce have to be stronger then outside water pressure.

We can guestimate it: to start a steady accent you'd need to blow 200-300l of water out (my wildguess). Here is a link, it states:

The air flasks have a total capacity of 6200 liters (219 cu. ft.) at 2920 p.s.i. This is sufficient air to evacuate all main ballast, fuel ballast and bow and stern buoyancy tanks once at a depth of 180 feet, or 5.65 times the free air volume of these tanks. Most of them are located in the superstructure, but six flasks which are part of four banks are located in the maneuvering room and engine room.

2920psi is 198atm, that means that at least theoretically we could blow out at least 6200 liter of water at any depth up to 2000m in type IX. But then of course you'd spent some air trimming while going to that depth so it is more like 600-700m... All that means that one could easily trim (and keep trimming) a undamaged boat at any depth in the operating depth range, in particular at speed when planes help. With all that I see no reason why the boat should accent or decent at any speed except dead stop. And at dead-stop I would expect to see some random depth oscilations not constant accent or descent.

[Stormfly]

ohh i just asked me if it would be possible to use pumps instead of air at this dept... so if pumps and energy are not strong enough to trim the boat at this dept, i think they wont had waste theier valueable air for trimming, but used the planes with a minimum speed.