(REQ) Slower U-Boat Dive Times and more accurate handling

[CCIP]

Originally Posted by Ducimus

Personnaly, i think 47 seconds is accurate for a fast dive on a 9D2.

I'd vouch on that too. I think the dive times listed in literature are always basically minimums and probably belie the real operational ones in complicated circumstances or when the attack was unexpected. I personally suspect that unless they were on top alert and with some of the tanks pre-flooded, even Type VIIs would probably take well over a minute to dive. I mean it makes sense to use a reasonably minimal value in the game, but I'd take a conservative estimate of that. Better to err on the side of long dives if you ask me!

[Old Dog]

Originally Posted by Ducimus

Personnaly, i think 47 seconds is accurate for a fast dive on a 9D2.

I like the new hat Ducimus ! Sorry to see that you're feeling so blue.

Long range sub equals large fuel tanks equals increased flotation to overcome. I imagine that dive times are a moving target. On a long mission, as fuel tanks contain less and less fuel (and more and more air) dive times increase, and that the larger the sub, the longer the time it takes to get the bugger under water.

[CCIP]

Originally Posted by Old Dog

I like the new hat Ducimus ! Sorry to see that you're feeling so blue.

Long range sub equals large fuel tanks equals increased flotation to overcome. I imagine that dive times are a moving target. On a long mission, as fuel tanks contain less and less fuel (and more and more air) dive times increase, and that the larger the sub, the longer the time it takes to get the bugger under water.

Good point! But there's a massive ton of other factors as well - just think of other things like fresh water tanks, or torpedoes, or anything else that basically changes the sub's buoyancy when it leaves the boat. Don't forget the infamous "all hands forward"! (though there's debate if that's really something that happened, given the relatively negligible weight of the crew). There's all sorts of complicated factors that SH4 doesn't really factor in. I really wish the sub's physics model accounted for ballast in a less generic way than it does. It'd really improve the feel of its performance.

But we only have to work with abstracted factors!

[DS]

I was under the impression that sea water was pumped into fuel tanks as compensating ballast as fuel was expended in order to solve this problem.

[Old Dog]

Originally Posted by DS

I was under the impression that sea water was pumped into fuel tanks as compensating ballast as fuel was expended in order to solve this problem.

DS, you're right by golly ! I remember reading that !
I can't believe that the reduction of fuel and replacement by sea water was absolutely 1:1 though.
Admittedly, I was never a sub guy, Army Engineers only, and a Poly Sci major at that !

Replacing expended fuel with sea water would theoretically reduce dive times. The specific gravity of fuel oil is less than that of sea water...that's why it floats !

I've lead a sheltered life and never had a satisfactory explanation of how one can mix sea water and deisel fuel in one tank and operate the ships engines on fuel from that tank, especially given diving and surfacing and the various shakes that depth charges would give to the contents of the fuel tanks. They must have operated on a very conservative estimate concerning the level of un-contaminated fuel remaining in the tanks. Trying to run the engines on sea water is not the kind of experiment I would be willing to try in a war zone. I believe that, even with the sea water, there was a significant amount of air in the fuel tanks.

Thanks for the memory prod though.

[Wilcke]

Don't forget fuel filters, you gotta have those for diesels or else the injectors, pumps are rubbish in no time. Brings memories, I used to be a farmer! Lots of diesel on a farm!

[Sailor Steve]

Originally Posted by Old Dog

I've lead a sheltered life and never had a satisfactory explanation of how one can mix sea water and deisel fuel in one tank and operate the ships engines on fuel from that tank, especially given diving and surfacing and the various shakes that depth charges would give to the contents of the fuel tanks. They must have operated on a very conservative estimate concerning the level of un-contaminated fuel remaining in the tanks. Trying to run the engines on sea water is not the kind of experiment I would be willing to try in a war zone. I believe that, even with the sea water, there was a significant amount of air in the fuel tanks.

And the funny thing is it wasn't just diesel, but also fuel oil. The Iowa class battleships used the same exact method to make sure stability never changed!

[NonWonderDog]

Err... the diesel fuel used in submarines is fuel oil, right? Isn't all diesel fuel not derived from vegitable sources "fuel oil"?