Submarine questions

[ABBAFAN]

When a submarine is running on the surface with both diesels on propulsion, does this mean he batteries are powering everything on board? Is there no other generator for lighting etc? How long would it take to charge up air and batteries at the same time? Would it be only one of the diesels connected to the dynamo or could both charge at the expense of propelling the vessel?

Also, if ballast is blown at a great depth would water need to be taken on on the way up to compensate for air in the ballast tanks expanding as the water pressure drops?

[AVGWarhawk]

What type of submarine are you inquiring about?

[ABBAFAN]

With regards to the diesels then Uboats. But any submarine with regards the ballast question.

[Platapus]

Fleet boats had a smaller engine/generator that could be used to power some of the support systems while on the surface.

BTW, you have a lot of nerve asking a legitimate submarine question here in GT.

Don't you know that GT is for whining and illogical emotional comments only?

[Sailor Steve]

If you're talking about modern diesel submarines, I'm pretty sure they are all improved versions of the diesel-electric drives developed by the Americans prior to WW2. The diesel engines do nothing but drive the generators. The generators 1) Drive the motors which propel the sub, 2) power the boat's systems, and 3) recharge the batteries. Of course while submerged the batteries drive the motors and power the systems. There is also at least one small axhiliary diesel engine which drives its own generator to help supply power and ease the load of the main generators.
http://www.maritime.org/fleetsub/elect/chap2.htm#2A

If you meant WW2 u-boats, they had the engines either propel the boat directly or recharge the batteries.


BTW, you have a lot of nerve asking a legitimate submarine question here in GT.
On the other hand we have a whole forum dedicated to this sort of thing.
http://www.subsim.com/radioroom/forumdisplay.php?f=186

[ABBAFAN]

With regards to the boats in SH3, Where you have a choice of having a diesel drive the generator or propell the boat with the other one, would having both propell the boat allow the battaries to slowly drain on the surface due to powering lights etc while both diesels are driving the screws? I know the game is a simplification of reality but just wondered. Would a uboat have had a mini generator for when both diesels are propelling the boat? As there would still be electrical needs of course.

[troopie]

Unkie Neil posted this youtube link to a USN training vid not long ago:

http://www.subsim.com/radioroom/showthread.php?t=200577


It won't answer your in-game questions but it provides great insight into the workings of a WWII sub :up:

[ETR3(SS)]

With regards to your second question, if you're in a situation where you are blowing your ballast tanks you probably are intending to surface. Otherwise if you just wanted to change depth, you use the planes. So no, you wouldn't blow ballast and then turn around and re-flood the tanks. To do so would be a waste of a limited resource, compressed air.

[Pisces]

... axhiliary ...Busted at your own pet peeve .... :O:

[AVGWarhawk]

Busted at your own pet peeve .... :O:

:haha:

[Sailor Steve]

Unkie Neil
You may be hearing from Onkle Neal soon. :dead:

[Sailor Steve]

Busted at your own pet peeve .... :O:

:haha:
You guys never actually read anything I write, do you? Yes, an embarrassing typo, but only a typo, which I never mention to others.

My own pet peeve is abuse of the language, not spelling. A so-called native English-speaker who doesn't know the difference between "your" and "you're", between "where", "wear" and "ware", between "there", "their" and "they're" is what annoys me. People who are too lazy to learn their own language. When I've been called on those myself I've been appropriately contrite. But spelling? It happens.

As I said, it looks like neither of you has ever actually read what I've written on the subject, and neither of you has a clue as to my "peeves", pet or otherwise.

[AVGWarhawk]

As I said, it looks like neither of you has ever actually read what I've written on the subject, and neither of you has a clue as to my "peeves", pet or otherwise.

Sure Steve. Watever you say. :salute:

[Sailor Steve]

Sure Steve. Watever you say. :salute:
What part of "That's my story, and I'm stickin' to it!" did you not understand? :O:

[ABBAFAN]

Returning to the point in hand, I meant that blowing ballast deep will lead to the air in the ballast tanks expanding and pushing more water out as the boat rises won't it? Is there a way they compensate for this?

[Pisces]

...

My own pet peeve is abuse of the language, not spelling. A so-called native English-speaker who doesn't know the difference between "your" and "you're", between "where", "wear" and "ware", between "there", "their" and "they're" is what annoys me. ...

As I said, it looks like neither of you has ever actually read what I've written on the subject, and neither of you has a clue as to my "peeves", pet or otherwise.Ok, makes sense. I do read it, but my memory lacks appearently. ;p Apologies for making assumptions about your peeve.

//off off-topic

[geetrue]

while on the bow planes at 400' on a 350' diesel submarine (USS Salmon SS-573)

I will never forget the Officer of the deck and the Chief of the watch yelling blow negative at the same time.

We came up very fast :yep:

for a more qualified study of surfacing a submarine you can go here:

http://www.heiszwolf.com/subs/tech/tech01.html

To surface the boat, the water in the MBT's is forced out by pressurized air. When the boat is deeply submerged, the water is forced out using high pressure air to overcome the water pressure. Once the boat is near the surface, the blowing of the MBT's proceeds with low pressure air. Once at the surface, the Russian boats close the Kingston valve and then opens the main vent valve briefly to equalize the air pressure in the MBT with that of the atmosphere. In the USA/UK boats, the main vent valve remains shut to keep the air in the MBT under pressure. The pressure inside the tanks remains equal to that of the low pressure air system.

[ETR3(SS)]

Returning to the point in hand, I meant that blowing ballast deep will lead to the air in the ballast tanks expanding and pushing more water out as the boat rises won't it? Is there a way they compensate for this? Correct. As you go shallower the water pressure decreases allowing more of it to be discharged from the ballast tanks by the higher pressure air. As more water is expelled from the tanks the air pressure will drop as it has more room to expand. As far as compensation is concerned, yes they could open the MBT vents to vent some of that air. But the $100K question is WHY would they want to do that? Like I stated before if you merely wanted to change depth you use your planes to proceed to the new depth. You don't blow ballast to go to a shallower depth.

[Schroeder]

You may be hearing from Onkle Neal soon. :dead:

Actually it's Onkel Neal.:O:
Busted again.:D

[Sailor Steve]

Actually it's Onkel Neal.:O:
Busted again.:D
Very true. My German isn't what it once was. In fact my German never was what it once was.

"Your" absolutely right.

[ABBAFAN]

I meant as a way of slowing the ascent or even to prevent it from speeding up as more and more balast is expelled by the expanding air already in the tanks.
Perhaps similar to rising and descending in a gas balloon?

On the other hand, would decreasing water density compensate anyway by reducig the boat's bouyancy as she rises?

[ETR3(SS)]

I meant as a way of slowing the ascent or even to prevent it from speeding up as more and more balast is expelled by the expanding air already in the tanks.
Perhaps similar to rising and descending in a gas balloon?

On the other hand, would decreasing water density compensate anyway by reducig the boat's bouyancy as she rises?Well in a hot air balloon lift is generated by the hot air in the balloon itself. As the air cools it descends thus making it necessary to heat the air trapped within the balloon to maintain altitude or to ascend. That's pretty well know.

A submarine operates on a completely different principle. When it submerges it takes on water in its ballast tanks to maintain a state of neutral buoyancy. Depth changes are accomplished by the use of the control planes. Once submerged the main ballast tanks aren't touched except to surface the boat. There's no need to blow water out or take water on except for when your displacement would change (consuming food stores, firing torpedoes, etc) and there is an auxiliary system for this purpose.

As for your second question about water density affecting buoyancy, I'll hold off on answering that for now.

[ABBAFAN]

I know about hot air balloons, I was making the comparison with gas balloons which are rather different.

Do they close the valves at the bottom of the ballast tanks once blowing has been done and the vessel is on the way to the surface?

[ETR3(SS)]

I know about hot air balloons, I was making the comparison with gas balloons which are rather different.

Do they close the valves at the bottom of the ballast tanks once blowing has been done and the vessel is on the way to the surface?My mistake about the balloons. In that case the comparison is even further apart.

Now about your question here, I can only speak to American submarines. The US boats have a vent valve on the top of each ballast tank and flood grates on the bottom. This maintains the water pressure in the ballast tank equal with that of sea pressure on the outside. It is my understanding that Russian boats have valves on the top and bottom of their ballast tanks. They submerge by opening both sets of valves. Once the ballast tanks are full of water both valves are shut. This maintains a constant pressure of the water in the tanks, that which would be nearer to surface water pressure. My conjecture is that you could blow HP air into the tanks and then open the bottom set of valves to force the water out quickly even at great depth. I would imagine that the valves would be closed again once the tanks were blown dry. I either used to have a diagram of this or saw one somewhere but damned if I can find it now. :hmmm: