View Full Version : Whats with the aft tubes?
deamyont
05-01-07, 06:10 AM
What are the aft tubes for? And four of them? Why did they chose to have them historicaly?
If it was my chose, 6 bow tubes, no aft, and use bigger/more batteries, bigger engine or more fuel instead. Maybee even a shorter hull. Anything but all those aft tubes...
TDK1044
05-01-07, 06:53 AM
For large Convoy's, they're very useful. Last night I fired my six main torpedoes, and then while those tubes were being reloaded I turned and fired my 4 aft torps. This allowed me to fire ten torpedoes in under two minutes. I sank 6 ships.
I sometimes use my aft tubes first, if it is a slow-moving convoy, which leaves my forward tubes ready for when things heat up a bit. Try it some time, you might like it.
They are also good when you get in a convoy, allowing you to engage in two directions, which (historically at least) would help to disguise your position a bit.
And if none of that appeals, try popping some at a pursuing destroyer in a spread, that occasionally works too, and is funny as hell when it does.
perisher
05-01-07, 08:23 AM
Historically, WW1 and just after, as subs got larger they had tubes facing all directions, including beam tubes (these could not be reloaded at sea). Pretty soon the beam tubes were dropped as a bad idea. (Difficult to use and took up a lot of space). Many navies kept the stern tubes, they could be useful but they were much more difficult to use than the bow tubes. The problem was getting a good angle while moving away from your target. Eventually everyone dropped the idea. First to lose it were the British, although the S and T class boats retained an external stern tube. That is, of course, a one shot only tube. As built the T class also had two rearward firing external tubes mounted one either side of the conning tower. These were turned around in a field mod and made to shoot forward, giving the T boats an initial bow salvo of 10 fish. That was six in the bow tubes, plus two external bow tubes in the casing directly above the normal tubes and the two amidships externals.
Between the wars the French experimented with destroyer style rotating tubes on the decks of their larger "cruiser" submarines.
Today, computer aided aiming systems would make stern tubes as easy to use as bow tubes but the stern tubes would seriously interfere with modern streamlining.
I quite often use my aft tubes, both in the ways that TDK1044 & Chock describe but also I like to engage a convoy with bow tubes, dive underneath the convoy and once past engage again with aft tubes. This then leaves me with open water ahead to make my escape.
Must admit though that I've never managed to sink a persuing destroyer. Their senses seem too sharp so I now don't even bother trying to engage and save my ammo for merchants.
7Enigma
05-01-07, 08:36 AM
From a theoretical and safety (of the ship and crew) standpoint, it would actually be beneficial to have ALL tubes AFT. This would allow you to lay and wait for your prey, fire off a salvo, then immediately be able to leave as directly as possible.
Having tubes foreward requires a sub to fire at their target, then evade by first moving CLOSER to the target while turning away. I know if it was my arse on the line, I would prefer to have the immediate exit rather then having to turn away as my ship is being hunted....
SteamWake
05-01-07, 08:39 AM
I have tried unsuccessfully to attack pursuing destroyers from astern and from the bow. Typically using a beneath the keel shot with zero success.
The DD usually veers out of the torpedos path or the torpedo fails to detonate.
In fact the only DD's I have claimed never new what hit them.
But the stern tubes are usefull they just take a little more planning to set up a shot.
perisher
05-01-07, 08:45 AM
From a theoretical and safety (of the ship and crew) standpoint, it would actually be beneficial to have ALL tubes AFT. This would allow you to lay and wait for your prey, fire off a salvo, then immediately be able to leave as directly as possible.
...
Not so easy in real life, submarines are not humming birds, to quote the guys at NYGM Tonnage War. You cannot get ahead of a convoy, go to periscope depth and just hover there waiting for your prey to cross your sights. You have to keep the boat moving or it will not maintain depth, it will either go up or go down but it will not stay at a constant depth. The game will let you do this, but a real submarine could not.
7Enigma
05-01-07, 08:54 AM
From a theoretical and safety (of the ship and crew) standpoint, it would actually be beneficial to have ALL tubes AFT. This would allow you to lay and wait for your prey, fire off a salvo, then immediately be able to leave as directly as possible.
...
Not so easy in real life, submarines are not humming birds, to quote the guys at NYGM Tonnage War. You cannot get ahead of a convoy, go to periscope depth and just hover there waiting for your prey to cross your sights. You have to keep the boat moving or it will not maintain depth, it will either go up or go down but it will not stay at a constant depth. The game will let you do this, but a real submarine could not.
So how about this then :p :
Do your typical 90-degree attack with foreward tubes at very low speed (say 1kt just to keep your depth), then go back 1/3'rd and dive to escape. I'm curious at how inefficient reverse is as opposed to normal foreward movement, and also if there was a significant increase in noise as compared to normal operation. And obviously the aft dive planes would be less effective, but the tradeoff might be worth it to get distance between your target and escorts quicker?
perisher
05-01-07, 09:44 AM
I seriously doubt that a submarine ever went astern except when manoeuvring in harbour, all ships are difficult to handle going astern and I would imagine that depth keeping going astern was next to impossible. I read something abourt this recently but I can't find it right now.
When I use my stern tubes, I approach on a parallel track to my target(s), when I am ready I turn sharply away and increase speed, as my firing angle comes on I slow the boat, centre the rudder and fire. If I want to evade I put the rudder back on, go to flank and dive, once under 200 ft I cut to 1/3, rig for silent and make a 90 degree turn.
Having said that, on my last patrol I got target fixation and ended up too close for the bow shot, so I went under my target and took him with the stern tubes.
SteamWake
05-01-07, 09:49 AM
Youd be better off flooding the ballast tanks and charge foward.
AhhhFresh
05-01-07, 10:01 AM
It's because convoy's zig-zag, and any competent zig-zag pattern should be very difficult to predict exactly even after plotting their course for hours. They could get their base course and be pretty certain where they were going to pass, but to set up to ensure a forward torpedo shot meant that you were risking getting "caught in left field" if they zigged away from you on your firing leg.
Subs got into position so that regardless of the final zig they would have a minimum range shot from either from the bow or stern. That is, that if that zig was to port or starboard it wouldn't make much of a difference.
EDIT: I should note that I've never seen anything other than a very basic zig zag pattern in SHIV, so it's somewhat moot... unless it gets sophisticated in the latter part of the war, which I have yet to play.
7Enigma
05-01-07, 10:27 AM
So can anyone comment on the noise issue with moving in reverse compared to foreward? (ie things like cavitation, increased turbulence, etc.)
jetthelooter
05-01-07, 10:39 AM
reverse was typically used on the surface for maneuvering not for underwater use as it used a LOT more energy to move the sub than moving forward and battery conservation was paramount. stern tubes were typically used for OMG!! WTF!! type of shot on destroyers that sneak up on the sub. they were also used for finishing shots on stubborn targets to save the bow shots. they were also used in nite surface attacks where the more powerful diesel engines could be employed for reverse maneuvering.
Sailor Steve
05-01-07, 11:35 AM
Why aft tubes? Ten is better than six.
SteamWake
05-01-07, 11:37 AM
Why aft tubes? Ten is better than six.
Would boat balance also be a factor ?
There was a story (from the book "Red Scorpion") of the Rasher when Henry Munson was the captain, he was out of bow torps and was frustrated trying to line up the stern tubes. It states he tried to back into position, but the rudder kept falling to one side or another and thwarting his efforts.
I believe he eventually got into position and was able to take a couple ships down.
Chuck
I use the stern tubes the same as the forward tubes ... I run the boat in reverse while using them. Just have to remember that for turns, the rudder needs to be in the opposite direction than where you want to go.
I bagged a couple merchants last night with 3 of the stern fish.
U-Bones
05-01-07, 12:33 PM
Given an opportune situation, any time I can get TO the target track in a timely fashion, I will leave it slowly at 90 degrees and open with my stern tubes.
When using the stern tubes I try to cross over the targets path and creep away into firing position. I don't think I've ever used reverse for anything. I find trying to get the boat turned 180 degrees at a slow enough speed to remain undetected is too slow to be useful.
Subnuts
05-01-07, 01:11 PM
I think it's useful to remember that the Fleet boats were called that because they were designed to fight with the fleet, not independantly of it. They were designed to run on the surface at high speeds, communicating with the main battle force, and finally submerging and "thinning out" the enemy before the fleet arrived. Therefore, it makes sense that they'd have a heavy torpedo armament, since a submarine sneaking inside of an enemy task force would need all the torpedoes it could fire. A Fleet boat sneaking inside of a task force could sink a battleship with it's forward tubes and a cripple another with it's stern tubes. When they designed the Fleet boats back in the early 30s, they never thought they'd be sending them againist lone merchants. Or at least that's how I'm seeing it.
SteamWake
05-01-07, 01:39 PM
they were designed to fight with the fleet, not independantly of it. They were designed to run on the surface at high speeds, communicating with the main battle force, and finally submerging and "thinning out" the enemy before the fleet arrived.
Sweet ! Where can I get that mod !!!
Oh nevermind :oops:
SingeDebile
05-01-07, 03:19 PM
when your intercepting a convoy i sometimes like to sit right in the middle of it... so ill use up all my forward torps for those infront and rear torps for those passing behind...
this may only be realistically possible without the manual tdc since it gets kinda crazy quickly when you are switching between targets
SingeDebile
05-01-07, 03:22 PM
From a theoretical and safety (of the ship and crew) standpoint, it would actually be beneficial to have ALL tubes AFT. This would allow you to lay and wait for your prey, fire off a salvo, then immediately be able to leave as directly as possible.
Having tubes foreward requires a sub to fire at their target, then evade by first moving CLOSER to the target while turning away. I know if it was my arse on the line, I would prefer to have the immediate exit rather then having to turn away as my ship is being hunted....
i like this
deamyont
05-01-07, 03:54 PM
From a theoretical and safety (of the ship and crew) standpoint, it would actually be beneficial to have ALL tubes AFT. This would allow you to lay and wait for your prey, fire off a salvo, then immediately be able to leave as directly as possible.
Having tubes foreward requires a sub to fire at their target, then evade by first moving CLOSER to the target while turning away. I know if it was my arse on the line, I would prefer to have the immediate exit rather then having to turn away as my ship is being hunted....
With all tubes aft, the sub would need to make a 180 degree turn after aproaching a convoy. This would take a lot of time at silent running at 2 knots, time it dont have. Also, it would show of the biggest possible signature towards all directions...
And youre not diving towards the threat. When attacking the convoy the escorts are on your sides, and even behind. Youre diving towards a harmless merchant.
No, all tubes bow. Aproach convoy stealthy, fire all torpedoes and crash dive. Escorts hear you but its to late for the ships in the convoy to evade the torpedoes. Even if the smaller ships might be agile enough to turn, they cant because of the other ships around them. While crash diving, turn. It looks like you dive towards the targets but youre now sailing away. And the escorts cant hear you over the sounds of sinking ships...
I like that over the scenario when you sneak in, and take minutes of extra time turning, giving escorts a chance to kill you before you even fired. :up:
In real life, do you think they would like the idea of taking a huge fleet submarine inside a convoy, rather than to stay at safe range?
deamyont
05-01-07, 03:59 PM
Why aft tubes? Ten is better than six.
If you only have time to fire those at the front, (check previous post) wouldnt it be better to have all torpedoes stored at the front?
Ducimus
05-01-07, 04:17 PM
I use my aft tubes for single merchants, to finish off a wounded ship when using a deck gun is not feasible, or as a means of self defense if pursued by a Tin Can.
Everything else gets a bow shot :88)
Sailor Steve
05-01-07, 04:19 PM
Ten tubes forward? Twelve? That would take a pretty big cross-section. Twenty-four torpedoes for six tubes? No room to store them.
The thinking was probably as Subnuts described, with the added safety of being able to shoot as you run. Even the Germans had one or two aft, depending on the boat.
perisher
05-01-07, 04:50 PM
The ten forward firing tubes in the British T class comprised of the "normal" six interior tubes in the torpedo room. Above them, outside of the pressure hull but under the casing, were two external tubes. (Like the external storage in a U boat, except these were launch tubes facing forward.) The other two forward tubes were either side of the conning tower, where the casing bulged out to allow a walkway around the tower. So they didn't do much to increase the cross section.
Very handy if you stumble upon the Tirpitz.
deamyont
05-02-07, 12:43 AM
Even the Germans had one or two aft, depending on the boat.
Not on the XXI :up:
7Enigma
05-02-07, 06:55 AM
From a theoretical and safety (of the ship and crew) standpoint, it would actually be beneficial to have ALL tubes AFT. This would allow you to lay and wait for your prey, fire off a salvo, then immediately be able to leave as directly as possible.
Having tubes foreward requires a sub to fire at their target, then evade by first moving CLOSER to the target while turning away. I know if it was my arse on the line, I would prefer to have the immediate exit rather then having to turn away as my ship is being hunted....
With all tubes aft, the sub would need to make a 180 degree turn after aproaching a convoy. This would take a lot of time at silent running at 2 knots, time it dont have. Also, it would show of the biggest possible signature towards all directions...
And youre not diving towards the threat. When attacking the convoy the escorts are on your sides, and even behind. Youre diving towards a harmless merchant.
No, all tubes bow. Aproach convoy stealthy, fire all torpedoes and crash dive. Escorts hear you but its to late for the ships in the convoy to evade the torpedoes. Even if the smaller ships might be agile enough to turn, they cant because of the other ships around them. While crash diving, turn. It looks like you dive towards the targets but youre now sailing away. And the escorts cant hear you over the sounds of sinking ships...
I like that over the scenario when you sneak in, and take minutes of extra time turning, giving escorts a chance to kill you before you even fired. :up:
In real life, do you think they would like the idea of taking a huge fleet submarine inside a convoy, rather than to stay at safe range?
My quote was based on the assumption that you were already past the intersection point, not that you were running towards it. It was mentioned that my idea was not practical due to the lack of hovering ability that the game allows (finding a likely intersection point and then idling aft tubes facing the enemy). So you would need to pass the intersection point and then very slowly (1kt) move away from your target(s), while readying your aft tubes.
This could definitely be done as you had described to good effect IF you were far enough ahead of the target so a long slow turnaround could be performed at a deep depth.
EMAPhil
05-02-07, 07:02 AM
7Enigma asked about the efficiency of Propellors in reverse.
The simple answer is they are very bad.
Fixed angle blades are optimised for a certain forward condition -so many RPM at an expected forward speed. This means the water hits the blade at exactly the right angle for power, efficiency and for a sub, noise level.
In reverse all this is totally screwed up, so all the above parameters are now awfull.
Think of each blade as a wing. Not many airplanes would fly going backwards! Even variable pitch propellors have an optimum setting and the further away you move from that sweet spot the losses start to mount.
sunvalleyslim
05-02-07, 05:29 PM
I have tried unsuccessfully to attack pursuing destroyers from astern and from the bow. Typically using a beneath the keel shot with zero success.
The DD usually veers out of the torpedos path or the torpedo fails to detonate.
In fact the only DD's I have claimed never new what hit them.
But the stern tubes are usefull they just take a little more planning to set up a shot.
Steamwake,
When encountering a DD bearing down on you, I go for a 0 angle on the bow of the DD. And I wait until he's less than 800 meters from me. In Sh3 it worked almost everytime. Mush Morton (USN) used the "down the throat" shot quite effectively in the war
Why aft tubes? Ten is better than six.
If you only have time to fire those at the front, (check previous post) wouldnt it be better to have all torpedoes stored at the front?
Yes, which is why they now design them in that way, but it is because of the control and guidance which now exists, making it possible to attack a target behind you from forward facing tubes. In most modern submarines the tubes are actually no longer even in the 'bow' which is taken up by sensors. They are placed further back where the hull has a greater diameter and more space.
As for the noise aspect of astern propulsion, there would be more noise and cavitation due to the increased power necessary to generate the thrust as well as the curve of the prop. A left hand prop would be turning right hand and vice versa causing cavitation. (At least, that is what I remember. It was a while ago.) In combat or submerged I doubt it would be useful or even safe. Control would also be a major factor. The pivot point would be at the wrong end of the rudder and dive planes, and a small amount of water flow would have a magnified effect and cause control issues.
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