From The Fleet Type Submarine NAVPERS 16160, June 1946, Page 177
(Available on-line at http://www.maritime.org/doc/fleetsub/)


From The Submarine Commander's Handbook (U.Kdt.Hdb.), OKM 1643, dated 1943:

From their training manuals, it seems that neither the USN nor the KM was aware of the possibility of a submarine remaining motionless at a constant depth. These manuals describe practical operations, not theoretical possibilities. (The theoretical possibility of establishing neutral bouyancy, and thus remaining stationary is indiputable. The question is whether this was done or could be done operationally, more especially in combat.)

Thankyou for all the info. Basically my boat constantly leaks so I have to run the pumps all the time to maintain a set depth. Which means I'll always make a noise when underwater. So if I sit on the bottom at say 160m, rigged for silent running will my boat slowly fill with water? :rolleyes:

No. The boat leaks enough so that you have to run the pumps sometimes when moving very slowly. When silent running you still must maintain enough forward momentum to use the dive planes to maintain your depth. It means you can't "hover" like the game allows. The boat will sooner or later begin to sink.

Very, very slowly. You will run out of oxygen long before there is enough water in the boat for you to notice. It will all be below the deck in the bilges.

Thanks steve! Can i hell get your loading screens to work... :(

Thank you, Steve, for explaining simply and clearly what I (and others) were struggling to communicate.:up:

I cant recall....

Is there a flooding level indicator in SH3 or SH4?

Yes, but it's per compartment. The compartments will show up with a "water level" on the damage control screen if they're flooding, and if you hover your mouse over that comparment, it'll tell you how long it is until the comparment reaches maximum flooding level, and how long it's going to take to pump the compartment out. If the time to pump out is longer than the time it'll take for it to flood, you're in trouble :timeout:

To the extent that your post described the NYGM mod, or H.Sie mods or whatever other mod, I would agree.

Such behavior is not modeled under the standard GWX mod.

Additionally, in real life, should a U-boat lose power or go all stop it would not sink but rather rise slowly to the surface. Forward motion is required not to keep the boat from sinking but to keep the boat from rising.

RL, whether the boat rises or settles depends on whether it is trimmed heavy or light. If it is trimmed to have some positive bouyancy, then it will rise. If trimmed to have negative bouyancy, it will settle.

Whether the boat is trimmed positive or negative depends on the situation. Generally, a slight positive bouyancy is preferred as a safety measure. In the event the boat loses all power, it will slowly rise to the surface.

In combat, when periscope observations were planned, it was safer to carry some negative bouyancy. The boat would have less chance of broaching, breaking the surface and exposing the periscope shears and the sail.

This topic is treated in NAVPERS 16160., and discussed in many of the first-person accounts, including Werner.

In-game, NYGM builds in negative bouyancy, GWX positive bouyancy, and stock SH3 lets you hover like a hummingbird. There is a parameter in a text file that you can change to adjust both amount and direction. I don't recall which file, but it has been discussed on this forum.

This is true. I wasn't thinking of the game at all, but of real life. My apologies for any confusion.

I can't recall the exact change, but it's my understanding that the positive bouyancy in GWX was removed after some complaints, and is not there in GWX3.

I don't know either, and I wish I did because while GWX is my mod of choice I like the 'sinking' function. It keeps me honest.

My personal experience, with GWX, is that when I set the depth for 25 meters and run silent I typically hover around 24 meters and never reach the 25 meter depth.

Steve, I found the thread:

http://www.subsim.com/radioroom//arc.../t-201357.html

The relevant post is one up from the end, by VanJast.

The file is Data/Zones.cfg, section PumpsXXI, parameter Flotability. VanJast says that he reduced the value from .15 to .005 and got a very slow settling. (50 m in 12 hours).

Although VanJast is a very reliable source, I was a little concerned because, when I checked the relevant file in GWX3 expecting to see positive bouyancy, the Flotability value was zero. If the positive bouyancy has been removed from GWX3, a zero value would be expected. I haven't tried tweaking the Flotability (and don't plan to), but for those who want to, Van certainly has shown us how.

Same here. I use GWX3 and when crawling along (submerged) at 1 knot, my depth is always a couple of metres less than ordered.
I always assumed, (probably wrongly), that it was due to sea density.

The differing viewpoints in this thread, have obviously sunk that assumption. :hmmm:

I can't remember what it was like in the stock version, as I have only used GWX for the past 5 years or so.

I don't know if this is related to it but i discovered that you need to click past the number if you want the number take place. Let me explain, if you want 5 knots speed, then you should click somewhere between 5 and 6 on the gauge. If you click on 5, then you will probably get 4 knots. Same for depth etc...

As you do, I run GWX and I run it from the day one. I don't know how the stock game is except for the one time I opened it and immediately closed it. I knew GWX by then and even the ships seemed ugly in the stock game after knowing how they looked in GWX.

Thanks Aras, that's the way I have been doing it.:up: