U-Boat sinks further after reaching critical depth

[chripsch]

Hi gents,

I just rediscovered SHIII after some time of break.(GWX 3.0)

When I am crashdiving with my VII-C boat and I pass the 150m
mark I get the notice "we`re reaching critical depth" and the boat
continues to drop... Just with an emergency blow out I could save
my boat.

While when I played the last time SHIII I could dive down to 220m
with my VII-C without any problems now I feel I must stay above
150 m. If I want to dive deeper the boat continues to drop until
the hull crashes... I can`t hold a depth like 200m.

Another "nice" experience is that when I am crash diving and I hit
the ground all crew members in the bow torpedo room are dead.
I recall that this problem in the past (some years ago) didn`t exist.

Where there changes at GWX 3.0? How can I fix this issues?!

Thank you very much for your help,
Christian

[Gunnarr]

First time I told my helmsman to crash dive command, he sent me too low and we crushed.

I always just put a manual number , but not as low as I want to go. I make sure that we stop going down, then I tell them to go lower

I'm afraid of it too, but not sure why it happens

[bstanko6]

If you engage crash dive, and at any time play with the depth before you reach I believe 80 meters, you will continue to dive. You can change your speed, direction, but you CANNOT change depth while crash diving!

[Rambler241]

This behaviour is simply reflecting reality. As I understand this in RL - reflected fairly accurately in SH3 vanilla (and GWX by the sound of it) is that for a normal dive, buoyancy is set to neutral (by the guy with all the valves & pipes), and the dive planes are set about 3/4 down in this formation /----\ (bow on the right). This pushes the bow down, and the stern up. Use external view to watch a dive and you'll see the stern almost lift out of the water as the bow goes down. As depth increases, the planesmen ease off the 'plane angles, and then gently reverse the process until the required depth is reached - controlled, gentle, and safe.

In a crash-dive (as you well know) speed is set to flank, and the 'planes are set to maximum angle, creating a greater down-angle than described above. Just before the required angle is achieved, the planesmen back off the 'plane angles, first bow, then stern, to zero. Now the boat is descending at flank speed at an angle of around 10° (or less, depends on boat handling characteristics). You may have heard the term "down bubble" used on American boats in movies - "Set seven degrees down bubble". The "bubble" was literally that - a curved glass tube containing oil and a bubble - a much larger and precise version of the one used in spirit levels. A curved scale showed the bubble angle in degrees - up or down, either side of centre.

Watch the process in the command room (no bubble visible though!). This is surely real life on a small screen. To bring the boat to a level attitude, the 'plane process is reversed, bow 'plane up, stern 'plane up, pushing bow up and stern down, reducing the 'plane angles gradually: \----/. This takes a while, hence the boat continues to descend, but at a reducing rate.

Back to this post - in a crash dive, around 800 tons (or tonnes if you're picky) of metal and men is descending at a steep (for a submersible boat, which is what WW2 submarines were) angle, at flank speed - a critical and potentially dangerous situation. Many boats from pretty much all nations have been lost due to mishandling in even a normal dive. Follow Jörg Neumann's (my current handle in SH3) overriding advice:

Rule 1: Don't hit anything (especially the seabed)
Rule 2: See Rule 1

My advice: Once descending steeply, back off the speed, say to standard, and hit "A" to abort the dive (or rise - applies equally) and maintain current depth. Issue a depth order now, if you need to. Once level, increase speed if you need to. If you have no idea where the bottom is, don't crash dive.

As a postscript, hitting a stony bottom at crash-dive angle is highly likely to result in the instant death of all those unfortunate to be in the bow torpedo room. Christian asked "how can I fix these issues?". The answer lies within, Christian, as with many things in both real life, and SH3.

[Karl Hungus]

I believe that you're approaching test depth when you get the critical depth warning- the boat is actually capable of diving deeper than this. I've had a severely-damaged IXD down at 260m before.


Correct me if this is wrong:

Test Depth < Calculated Crush Depth < Actual Crush Depth (if you're lucky)

[banryu79]

Originally Posted by Karl Hungus

I believe that you're approaching test depth when you get the critical depth warning- the boat is actually capable of diving deeper than this. I've had a severely-damaged IXD down at 260m before.


Correct me if this is wrong:

Test Depth < Calculated Crush Depth < Actual Crush Depth (if you're lucky)

1) Yes, and if one use SH3Commander to launch the game a "random crush depth" feature comes for free. That's great, I mean, you take out for your next patrol and you do not know precisley how much deep you can push her...

So one of your habit when you start a patrol will become to find a suitable area to go and test how deep you can put your boat before taking damage. (in a Type VIIB I usually go to 200 meters and level, then, slowly going down in steps of 5-10 meters until stating taking damage and making my men mad on me or until I feel it's enough )
Of course, before taking your "deep diving stress test" ALWAYS designate a Damage Control team and make it ready!
Also, order a speed of 3 knots, your hydroplanes will be able to keep your boat at level.
Observe how the planesmen regulate the hydroplanes angle to keep the boat at level with different ordered speed (3 kn, 2 kn and 1 kn).


2) To correct once and for all the "crush diving bug" in the vanilla game just install the famous (and awsome) H.sie Patch. In any case, I like to fine tune my divings, so, in an emergency you could do as I do: do not press the 'C' key. No, no, don't do it. Istead issues the following commands:
- ahead flank
- Dive! (press the 'D' key)
- reaching 10 meters, when electric motors kick in: ahead full!
- now command your desidered depth (let's say 150 m.)

Then you keep mantaining 'ahead full' (or 'ahead standard') and when you are approching your chosen depth (40 meters or less, in our case 110 meters depth) command: 'ahead standard' (or 'ahead 1/3').
You can choose for a quicker but noisier descent VS a slower but less noisy one.

[Rambler241]

Diving Regulations for U-boats might be of interest. The translation from the German is a bit clunky, but both instructions and warnings are crystal clear.

Para. 113: "Attention must be paid to sufficient water depth"

Indeed.

The index page links to several other docs also, including a report on the capture and inspection of U570. which begins

"Graph," ex "U 570," is a 500-ton U-Boat, Type VIIC, and was built at the Blohm & Voss Yards, Hamburg. Commissioned on 15th May, 1941, with a crew consisting of 4 officers, 3 chief petty officers, 11 petty officers and 25 men, she carried out trials, mainly from Kiel and Horton, on Oslo Fjord, until about 23rd July, when, during a crash dive from a suspected British aircraft, she struck a reef and damaged her bows.