Crash Dive Question

Originally Posted by 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!"

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]

Originally Posted by Albrecht Von Hesse

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?

Originally Posted by Sailor Steve

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/...ssue_23/s5.htm