Crash Dive Question

[Segwin]

Hello All:

If you're in shallow waters and give the crash dive command will the crew know enough not to bottom out the boat or should I first know the depth and then dial in a proper depth?

TIA

[con20or]

They'll bury her up to the screws if you let them.

Always sound before you dive, if there are escorts bearing down on you it may be the last chance you get to do so anyway!

[squirrel777]

When you want to dive in a hurry in shallow water, press 'C' (crash dive) and then, 5s later select your depth ('P' if it's really shallow).
Your crew will get down much faster than by just selecting a depth and you will avoid touching the bottom. You will still need to ping before though (or ping while the crew prepares for diving, after hitting 'C').

[AVGWarhawk]

They'll bury her up to the screws if you let them.

Always sound before you dive, if there are escorts bearing down on you it may be the last chance you get to do so anyway!
That is funny man!!!! Anyway, what I do is hit crash dive and then hit the A key for maintain current depth. But yeah, if you hit crash dive the crew only hears crash and that is just what they do, crash into the bottom.:shifty:.....training by Bernard I suspect!

[Sailor Steve]

Actually that was also true in real life. In a crash dive all tanks are fully flooded, the trim ballast water is pumped to the forward trim tank, the planes are put on full dive and down she goes. No one yells "Crash dive, but only to periscope depth!" 70 meters is about as quickly as they can level off in those conditions.

It's the captain's (and the duty watch officer's) responsibility to know how deep the water is under the boat. If a plane or destroyer is spotted close enough to warrant an emergency they didn't usually check the conditions, they just shouted "Allaaaarrmm!!". If they were near the coast or knew it was shallow they would probably just say "Periscope depth...NOW!"

[Segwin]

Speaking of periscope depth, on more than one occasion I have been at periscope depth and have had the destroyed run (I think) over me breaking all the glass in the gauges and causing all sorts of damage. I say I think because I'm not using any event camera. If you're at periscope depth should this happen?

If it sounds like a nub question it's only because it is. ;)

Using 1.4 patched to TGW.

[AVGWarhawk]

Speaking of periscope depth, on more than one occasion I have been at periscope depth and have had the destroyed run (I think) over me breaking all the glass in the gauges and causing all sorts of damage. I say I think because I'm not using any event camera. If you're at periscope depth should this happen?

If it sounds like a nub question it's only because it is. ;)

Using 1.4 patched to TGW.

Yes, the destroyers will run you down!!!! I think some more damage should occur when the conning tower is mowed down by a destroyer. I have been hit with my scope up but no damage. Other times I have been hit with the scope down and then it is broken and will not go up. Anyway, even at periscope depth you are vulnerable to the hulls of warships.

[HEMISENT]

The periscope damage was a real sore point for me. During testing for another mod awhile ago, I set up different test scenarios having a warship run over my boat. Different angles, speeds, sea state etc. Most of the time the scope suffered little or no damage. This was before NYGM 2.2 now I think this problem has been solved.

[Steeltrap]

Bear in mind the problem with maintaining depth after you interrupt a CD. There's a thread on it somewhere.

You can change the depth to which you level off after a CD. I know U-boats trained to get to 20m in 25s according to Peter Cremer.

I've configured mine to level at 30m.

[Segwin]

I've configured mine to level at 30m.

How did you do that?

[melnibonian]

I've configured mine to level at 30m.

How did you do that?

I think you edit the cfg files, but I can't remember which one. I'll have a look and let you know later on as I'm at work right now.

[Cpt.Thorne]

Interrupting CD evolves into Crash Dive Blues
See here
http://www.subsim.com/radioroom/showthread.php?t=92883&highlight=crash+dive+blues

[Albrecht Von Hesse]

Actually that was also true in real life. In a crash dive all tanks are fully flooded, the trim ballast water is pumped to the forward trim tank, the planes are put on full dive and down she goes. No one yells "Crash dive, but only to periscope depth!" 70 meters is about as quickly as they can level off in those conditions.

It's the captain's (and the duty watch officer's) responsibility to know how deep the water is under the boat. If a plane or destroyer is spotted close enough to warrant an emergency they didn't usually check the conditions, they just shouted "Allaaaarrmm!!". If they were near the coast or knew it was shallow they would probably just say "Periscope depth...NOW!"

I'm not totally sure about this, as I'm going strictly from memory. But in instances where a sub wanted to assure the absolute minimum time to dive, they 'rode the vents'. Ballast tanks have Kingston valves at the bottom, and vents at the top. What they did was keep open the bottom Kingston valves, open up all the internal valving ahead of time to the ballast and negative tanks, but keep the upper vents closed. This kept water from inflowing and flooding the tanks as the air inside was trapped. But in the event of needing to crash-dive, all that was needed was to open the upper vents and away you went.

Drawbacks to that I would think is if you didn't get the main induction valve or conning tower hatches closed fast enough. --shudders at the thought of prematurely diving without a green Christmas tree--

[davidaspy]

If its really serious i crash dive even in the shallowest water (15m is my record). Id rather hit the bottom and be damaged than have that planes bombs connect. Its the lesser of two evils. Also time spent pinging is time not spent diving. Press 'c' first and then ping. This mentality has saved me more than once.

[Sailor Steve]

I'm not totally sure about this, as I'm going strictly from memory. But in instances where a sub wanted to assure the absolute minimum time to dive, they 'rode the vents'. Ballast tanks have Kingston valves at the bottom, and vents at the top. What they did was keep open the bottom Kingston valves, open up all the internal valving ahead of time to the ballast and negative tanks, but keep the upper vents closed. This kept water from inflowing and flooding the tanks as the air inside was trapped. But in the event of needing to crash-dive, all that was needed was to open the upper vents and away you went.

Drawbacks to that I would think is if you didn't get the main induction valve or conning tower hatches closed fast enough. --shudders at the thought of prematurely diving without a green Christmas tree--
Another drawback, as I said, is that there is no way you're going to open up everything, diving as quickly as possible, and then pull out at periscope depth, or even thirty meters. As to your <shudder>, did they ever 'pull the plug' without a green christmas tree?

[Albrecht Von Hesse]

Another drawback, as I said, is that there is no way you're going to open up everything, diving as quickly as possible, and then pull out at periscope depth, or even thirty meters. As to your <shudder>, did they ever 'pull the plug' without a green christmas tree?

I agree! I don't see how you can set everything for a max-rate of dive and expect to abort that half-way through and level off at periscope depth, or even 30 meters for that matter. That's a lot of inertia driving you at that point.

I've never read of an account where a dive was started intentionally without a properly functioning green board. I'm almost positive that that's considered 'against the Book'. But I have to wonder if that didn't happen in wartime a lot. Shaving seconds here and there might be risky, but so is being a sitting duck half-submerged as ashcans rain down around your ears.

I've seen several war footage videos on-line (mostly on youtube). Mostly they've been propaganda ones. From the films it does seem as if they're already setting dive planes and flooding tanks even while the watch crew is still clearing the bridge. As an open conning tower hatch would definitely red-light the board, it appears as if they are starting to dive without a full green board.

With regards to SHIII, the game certainly lets you start a dive without full green. There's no way the diesels should run as long as the game has them run. The main induction (the air intake that ventilated the submarine on the surface, and in particular, supplied external air to the diesel engines) is one of the biggest --and potentially fatal-- openings through the pressure hull, and diving with it remaining even partially open is deadly.

The S-5 sank due to the main induction being left open. That sinking was also the driving force to design and implement automated indicator boards (the Christmas tree).*

I'll keep researching. :hmm:

*ref: http://www.chinfo.navy.mil/NAVPALIB/CNO/N87/usw/issue_23/s5.htm

[Steeltrap]

I've configured mine to level at 30m.

How did you do that?

It's in the .cfg files. There is a folder for each u-boat type. Each contains a line "crash dive = x". I'd give the specific folder/sub-folders but I'm at work, not home.

Just change that to whatever you want and that's where it levels. NYGM 2.2 set it to 20m (stock is set at 70m). I believe that was to allow you to dive quickly and then not have the "interrupt" problem. You end up levelling at whatever depth is there. Diving after that is done by selecting the depth per usual or just pressing "D".

As for diving before a green board, Cremer says he usually opened the main vents himself after dropping down from the bridge. On some occasions he says there was already water starting to wash around the base of the tower, but I'm not sure how that would happen without the vents being opened first (not a submariner, so I don't know.....). He also tells a story of how one colleague ended up diving so quickly that he had his cap knocked off in the scramble down the hatch, didn't have time to grab it, so the boat dived and left his cap floating on the surface! Quite an amusing scene after the fact, but probably a bit more nerve wracking at the time.

[Albrecht Von Hesse]

. . . On some occasions he says there was already water starting to wash around the base of the tower, but I'm not sure how that would happen without the vents being opened first (not a submariner, so I don't know.....). . .

Perhaps the dive planes were already set to dive? That would begin forcing the boat under even with the tanks empty.