[tec] How to shoot a simple "salvo" or "Fan shot".

[Ducimus]

One of the biggest adjustments any old timer or new sub simmer experience, is with the American TDC in SH4. It is simply, just fundamentally different, and not having an explanation, will leave you scratching your head wondering why all your shots miss, or all hit in the same place. So.... lets talk about salvos.


First, lets assume you already have your target speed, AOB, and range inputed into the TDC, and you've enabled that nifty handy dandy position keeper and are just waiting to shoot. Such as in this picture:


Note the gyro angle on the torpedo, speed, and range to target. In this setup, I will be shooting VERY soon, as the target will be on the firing point very quickly. At this time, i should already have my torpedo speed and pistol selected for the torpedoes i intend to fire.


As part of prepping the torpedos aside from pistol and speed selections, i should open the outer doors for all torpedos i intend to fire. Given this is a porpoise class , with a cruiser as a target (certainly one you'd want to make sure goes down), i will be firing all four of my bow tubes. As such, they are all open in this picture. Forgetting to open a tube can cost you valuable seconds later on, which will result in a miss. So have them open NOW.


Here i am about to fire the first shot of a 4 fish salvo. Note ahead of time which direction the target is going in your periscope. Is he moving from the right, to the left? Which way hes moving is important, because it dictates which direction you offset your torpedoes. A simple rule of thumb is, "If hes moving to the right, offset to the right, if hes moving to the left, offset to the left". Or in other words, Offset in his direction of travel. If your shooting using your Bow or stern tubes, it doesn't matter, just note which direction he is moving in your periscope, and offset in that direction. The first shot in a salvo, you usually will start with a 0 degree offset if your sure of your targets speed.



Here i have fired my first torpedo at 0 degree offset, and am prepairing my second shot in this salvo by moving the offset angle 1 degree to the right. Special note here: The closer you are to the target, the wider the offset angle you'll have to use. The farther away from the target, the less offset you'll have to use. I have no set formula for this, only what my gut instinct tells me at a given range. Usually if the range is 2,000 or more yards, i'llll fire a 3 fish salvo at

0 degree offset
0.5 degree offset
1 degree offset.

In this scenario since the target is much closer, im using a larger offset angle, by 1 full degree per torpedo.

And again, Note the direction of the ship, and the direction i am spinning the offset angle. Both are to the right. (Again, if the ship was moving to the left, then id use a left offset angle)


In this screenshot, i have already fired torpedos, 1, 2, and 3, and am prepairing to fire the last torpedo. With each torpedo i adjusted the offset angle.

a.) Starting from 0 degrees offset, i then fired tube one.

b.) Then, i moved my offset, one degree to the right, and fired tube 2 about a couple seconds later.
c.) then with my offset angle still at the same position in the above step b, i then moved my offset again, one more degree to the right, to a total of 3 degrees, and then fired tube 3.

d.) Now, with my offset angle still at its previous position in step C, i again move the offset angle one more degree to the right, for a total of 4 degrees, and fire tube four.

Note the red lines i annotated in this screenshot, each one represents the offset i used when firing this salvo.

It may sound confusing, but Think of it, as "walking your torpedos to the right" (or left as the case may be). Or perhaps another way to state it, is, "walking your torpedoes in the targets direction of travel"



Here you can see how ive been walking my torpedos into his direction of travel.


And here you can see where the shots are ending up. The target has seen the torpedos, and has been taking evasive action. Unfortunatly for him, by the time he noticed my fish, it was too late to do anything about it. At any rate, my first shot in my salvo with the 0 degree offset has hit just aft of the middle of the target. Presumably because the target was starting to increase its speed.


The next couple of torpedos hit and space them selves out nicely enough.


And here is the results of our handywork. Two fish hit in the same spot, one hit forward, and another was a dud.



Hopefully this helps. With an understanding of the basics, and with some practice, firing a basic salvo in SH4 will become second nature to you.

[WhiskeyBravo]

Thanks Duci, nice tutorial, I'm going to give this one a try.

WB.

[claybirdd]

Thank you for sharing this, as I have been using the wrong gyro setup. Say I am in the above situation, I have always fired the first shots with port gyro the middle 0 and the later with a starboard offset. So again thank you for sharing.


If only I could get the dang AOB right. My solution does not get accurate enough untill moments before i have to fire. After much brow beating, I have implemented my own version of the O'Kane method. Preset AOB to 90(or close to it), and get range at the last minuite(almost always less than 1000). Speed I would get way earlier on.

[joegrundman]

Nice tutorial, indeed, but i disagree with the rule of thumb regarding defelcting in the direction of travel.

If for what ever reason you have overestimated target speed, you will miss with all your torps this way.

I think it is mathematically hardest for a target to avoid the sequence stern ->mot ->bow

[Ducimus]

Originally Posted by joegrundman

If for what ever reason you have overestimated target speed, you will miss with all your torps this way.

Very true, which is why i said.. "The first shot in a salvo, you usually will start with a 0 degree offset if your sure of your targets speed."

If your unsure of his speed, then you'll have to spread your torpedo deflection out much wider in case hes going slower then you think he is. (-1 degree instead of 0 which is MOT). Or a degree or two more in his direction of travel if you think he might be going faster then what your speed estimates are saying.

Personally, i just make sure i get my speed estimates right. But yes, i do miss on occasion, it happends.

[M. Sarsfield]

I always make one stern shot when I fire a salvo. Sometimes that high speed target sees the fish coming and turns hard. Now, the stern shot becomes a bow hit.

[Rockin Robbins]

Had an additional function of the TDC which we do not have. They could input the ship length and get the TCD to calculate the spread from stern to bow. Usually they would do 100% of the ship's length, but could increase that, guaranteeing misses, if they were unsure about input parameters and wanted a wider spread.

In our simulated submarines, they have dispensed with the calculated spread and we substitute the "by guess and by golly" spread. I'm afraid there is no way to close that gap if you're shooting a divergent spread where each torpedo takes a separate track.

[M. Sarsfield]

A good spread observation can be made with the scope, noting the degree difference between bow and stern. The spread will always be conservative, since the target profile (AoB) will be at a small profile 99% of the time from time of observation compared with time of launch.

[Soundman]

Yes, Duciboy...(Just kidding hehe)

This is a little bit off subject, but one I have wanted to ask for a long time. I've noticed you can set speed selection and/or Magnetic/Contact switches for each torpedo in advance, i.e. they are set independently, but this will not work for the offset. It would be great if the offset angles could be set in advance, ahead of time, instead of ...set angle-fire, set angle-fire, set angle-fire. My question for your consideration is....Could this be modded or is this hard coded.

A technique I have used at times on small convoys in a trail formation, is to anticipate the angles between the two boats position at the time of firing and my position, using large offset angles. The advantage is you can fire at both ships at almost the same time and thus disallow the second ship the time and/or chance to start a zigzag course or avoidance in general. This technique requires perfect positioning and timing, along with very large (sometimes maximum) spread angles. At times, it also requires firing from 1400 to 1800 yards or so, depending on the spacing of the two targets. It's very rewarding when done successfully.

[M. Sarsfield]

That's a neat approach to the multi-target problem.

I use the attack map to show me time to each target and then time the two launches accordingly after the chrono starts timing the first launch. I've gotten simultaneous hits this way - obviously, you you shoot at the trailing target, first.

Speaking of chrono, why do the u-boats have the ability to show different times on the chrono for each torpedo, but the US subs do not? I know they brought the ability over from SHIII, but it would have been nice to add it to the fleet boats, too.

[clayp]

Whats a "pistol"?.....

[Ducimus]

Originally Posted by clayp

Whats a "pistol"?.....

What dictates how the torpedo warhead will explode. In other words, do you enable magnetic, or have the torpedo contact only?

Magnetic, the torpedo will explode when it senses its close to the target (IE, set the fish to explode under the ships keel), but also by a direct contact will detonate it as well. While more robust, its also sensitive to ocean waves, and may premature.

Contact, the torpedo will explode by contact hit only. While less robust, its chances to premature are alot less then a magnetic setting.

[clayp]

Originally Posted by Ducimus

What dictates how the torpedo warhead will explode. In other words, do you enable magnetic, or have the torpedo contact only?

Magnetic, the torpedo will explode when it senses its close to the target (IE, set the fish to explode under the ships keel), but also by a direct contact will detonate it as well. While more robust, its also sensitive to ocean waves, and may premature.

Contact, the torpedo will explode by contact hit only. While less robust, its chances to premature are alot less then a magnetic setting.

Thank you very much sir....

[Buffalo9]

Good technique, the spread works well on convoy's that have overlapping.
Though, i've noticed that they stay abeam pretty much until you shake them loose, then it's a free for all.

[Dmsdmullins]

When i fire on convoys in trail i try to shoot at about a 30deg aob either comming or going. If you miss there is a slight chance you will hit someone in the next row. Just a thought, every little bit helps including luck.