[Q] Manual targeting

[Tachyon]

Originally Posted by Pisces

If you need to turn in the same direction as the target crossing your view:
target left->right; you turn right/starboard: you adjust AOB by adding your course-change to the currently set AOB.

target right->left; you turn left/port: you adjust AOB by adding the course-change to currently set AOB.

If you need to turn in the opposite direction as the target crossing your view:
target left->right; you turn left/port: you adjust AOB by deducting the course change from the currently set AOB.

target right->left; you turn right/starboard: you adjust AOB by deducting the course-change from currently set AOB.

Could you clarify that for me please? By target left-> right, do you mean that the target is moving on the scope from the left side towards the right?

Let's assume my current AOB to the target is 90 degrees. So, if my U-boat's heading (not AOB) is say..50 degrees, the ship crosses from left to right and changes course slightly, I rotate starboard 30 degrees to keep up with the ship. My new AOB becomes 30+90 = 120 ?

[ppk]

Visualize it graphically ... And it all becomes very simple. I can't believe I even asked the question in the first place . It's elementary school geometry..

[Tachyon]

That's kind of how I visualized it too, so what I posted was correct?

[richardphat]

Or Or.......... get you a sonar.
You need the 2 bearing contact, 2 distance and you check contact from the two bearing contact.
Time watch is not needed to find the AOB but important to find the target speed.
You do trigonometry.
With trigonometry you got the speed target
You have the course of the boat.
Cruise parallel to its course at the same speed.
Now get a new bearing.
(180- new bearing)= AOB.


Note this is purely Theory, when you get in game. The hydrophone, and every device which helps you to make your plot are not accurate. And plus you have to act fast.
Hmmm you ask me how i figure out? Just playing with trigonometry

[ppk]

As I understand it the AOB is irrelevant to your own course. It is the angle from the target's bow to your boat, with no consideration for the direction you are pointing to. The picture I made illustrates the situation where you want to point your bow at the target to take a shot at it, so it isn't actually where I pictured it, it is traveling along the red line and the AOB values I gave are only good at the two moments where this red lines meet the relative bearings to your boat (which did not move significantly, only turned it's bow). In other words, it is the AOB at 000 gyro angle. It changes because you are pointing to a point further along the target's trajectory and then waiting for the target to get there.

I'm not exactly sure about what you posted since you don't specify the target's course change but if you were to match it exactly then I don't think there would be a significant change in AOB, as long as you turn quickly enough.

[Tachyon]

Ok, so let's forget that I mentioned the ship was changing course. My sub is on the starboard side of the ship. Let's assume the ship was heading from left to right without any course change and my AOB was at 90 degrees starboard. The ship still hasn't crossed the center of my periscope.

Meanwhile, I rotate my U-boat slightly by 10 degrees to starboard, so new AOB would be 90+10 = 100 degrees?

This is exactly as Pisces posted?

If you need to turn in the same direction as the target crossing your view:
target left->right; you turn right/starboard: you adjust AOB by adding your course-change to the currently set AOB.

[ppk]

That's it

[UnderseaLcpl]

I can't offer the detailed advice given above, but I do have a few tricks that may help, if you're still interested.

In my experience, if an escort is drawing too close, you already messed up. There are two keys to baggin the big ships consistently. One is plannning, and the other is targetting.

Personally, I don't even use the TDC, even though I use manual targetting. (apologies who heard this song and dance before) Quite frankly, it is not necessary. Use a fast G7a and lead the target by one degree for each knot of speed at 90 AOB. The gyroangle should be 0 (or 180 for aft tubes, of course)
This approach eliminates the need for AOB calculations and allows for quick firing as targets present themselves. Just wait for them to cross your aim point. When targets zigzag, maintain the same lead, but aim no farther forward than the foremast, to reduce the chance of topedoes missing forward due to the relatively reduced speed of the target. As long your AOB is 90 (or close), and the tubes are open, the torpedo should hit on or very near the point where your periscope was centered when you fired, no matter the range. Attacks at leass than 2000 m produce the best results however, as the closer the ship is, the less time there is for calculation errors to manifest themselves.

Also, I like to use impact pistols only, set for 2m for 2500 tons and under, or Granville-class ships, and 3m for everything else. Two per ship. I have yet to meet the merchant that didn't sink from two closely-placed shots, especially on the bow area, and I have yet to see an impact pistol detonate prematurely or hit the ship's bottom in rough weather and dud.

Another important consideration is how you find and set up attacks on, convoys, which you didn't mention. For me, the best way is to submerge and hunt by hydrophone, as it gives me a much wider search radius, and therefore, the time to develop my attack. With the map contact updates on, you can plot the convoy's course and speed with a reasonable degree of accuracy by using the bearing lines and the three-minute fifteen second timed marks method. If not, the hydros will at least let you know the general heading of the convoy, distance, and whether they are approaching or moving away. Enough info to place yourself within a cone of probable courses that will likely allow you to establish visible contact.

Simply place yourself on a relatively perpendicular angle and wait for periscope contact. Make some final adjustments to get yourself a nice 90degree aob, taking note of any escorts positioned in front of the convoy. Ideally, you want to stay 2-500m from the outer limits of their track, and always 3-500m after 1943 or so. Destroyers cheat and use their hydrophones and ASDIC at high speeds, so keep the engines at slow ahead, switching to slow back if you get too close to their track. Personally, I never stop. U-boats sank if they stopped so I don't do it. I'm sure you have notcied the tendency of escorts, especially the lead escort(s), to cirlce back from time to time, so give them a wide berth once they pass you if they are doing this.

Always go for the center lanes (maybe stating the obvious) as they usually hold the best stuff.

Basically, with an on-the-fly targetting system like this, and a proper pre-attack set-up, you should never have to worry about being detected before you attack, or having to change position rapidly to avoid an escort or attack a target. Convoys are cooperative like that.


A few post-attack tips; don't dive, and especially, don't crash-dive after the attack. You may get another shot (from a reload) before the convoy passes, and you can keep track of the escorts. They may not know where you are. If you use my method to successfully launch multiple torpedo attacks in rapid succession, and in rough weather, this is even more true. It is often possible to slip out of the convoy and away at periscope depth without ever losing track of the escorts.

Escorts cannot use active and passive detection at the same time, so if you must dive, go deep and thin them out as much as possible by dropping 2-5 BOLDs in quick succession. Several will pursue the false contacts and, even better, keep getting in each other's way, giving you time to distance yourself.
One or two will always keep track of you, so stay at dead slow until you hear depth-charges or you hear "Wasserbomben!" I don't trust my hydrophone operator to find his butt with both hands and a map in these situations, so I use the station myself, but maybe yours is better.

All you really need to do is keep track of circling escorts and their speed. If they aren't going around you 360 degrees, they are cirling somewhere else and you needn't worry about them. If they are, listen to the loudest one for a change in engine pitch. That's an attack run, of course. If he's perpendicular or near-perpendicular, go to flank for about twenty seconds. You're in his baffles for that time, and it should get you away from the K-guns. Then focus your attention on the next loudest one.

Going to flank speed and changing depth ( ilike 220 as my standard, plus or minus 20 depth changes) after an attack is almost sure to make them lose ASDIC contact, and eventually, they will switch to passive sensors and lose you when you go back to slow. Eventually, you will reduce the number of pursuers to one (tedious sometimes)

At this point, evade the next attack using the prescribed method, but go to fulll reverse when you hear the charges burst and full rudder (once you're going backwards) in the direction he went after his run. Now you are loud and directly in the path of his next attack, which is right where you want to be. Wait for him to come to a near-zero, bearing on the hydros, making minor rudder adjustments to provide him with it. Then, you listen until his sound recedes from the zero-bearing and go to flank speed for about 5 seconds. Turn the engines off, and swing your KDB or Balkongerat around to 180 and see which way his contact goes. If he goes to his left, turn left, if right, go right, at flank speed for another 10-15 seconds.
In this manner, you can not only place yourself outside the next search circle, you can also present a minimal profile to your assailant.
To be honest, it doesn't always work the first time, and he may set up another attack run from stern-to bow, but even this can give you another opportunity to escape his net. Depth charges take quite a while to sink to 200m or so, and that's your window to go the opposite way.

Maybe it's not your style, but I hope that some of these tips can help. They have served me well in my careers, and I hope they can serve you well, too.

Happy hunting,

The Lance


edit, I probably should have mentioned that I hunt only where convoy routes converge. There is a lot of air cover later in the war, but if you stay submerged during the day and only surface to recharge when oxygen is at 50% or so, at night, it shouldn't give you a lot of problems. Also, beware the Schnorkel. I only needed one career ended by bombing while schnorkeling toteach me that. Gibraltar, AM52 (or maybe it's 25, whatever is off the North Irish Coast) and BF15 are prime hunting grounds. BF15 not so much because of the shallow water.