Just had a horrible couple of hours (IRL time) - went 3 (yes - three!) weeks without a contact in reasonable weather. I was so bored I thought I'd go up by Loch Ewe for some excitement.

Low and behold I get a contact in atrocious weather, bt I thought sod it - have a look to break the boredom. I had to get within 200m to see what it was. Guess what - a sloop! LMAO!

I had to dive to 140 and evade a few DDs to get away LOL.

I just saved and came out the game because I was fed up.

Give manual targeting a try sometime. The key to making it work is planning ahead by predicting where a contact will be and then arriving in time to take up an ideal shooting position, using stealth not to give yourself away.

I used to cruise around in auto target mode shooting at anything that moved from ridiculous distances and ridiculous gyro angles. Then I learned about the "Dick O'kane" intercept method and all of a sudden I was playing a completely different (and way more immersive) video game. I'll explain it a bit below though there are plenty of tutorials on SUBSIM.

The technique relies on this basic premise: One can hit a target with SURGICAL PRECISION if one can precisely determine the target's position, speed, course.

Notice I didn't mention range? You do not need to know your current range to the target in order to hit it using this technique AS LONG AS THE GYRO ANGLE IS ZERO. In other words, as long as the torpedo does not execute a turn after leaving the tube, the range to the target has no effect on the firing solution. If you don't believe me, just take it on faith for now and read on. You may want to use range to determine the target's position and course, but once those have been determined, you need not take any further range measurements.

The goal is to arrive at a position 2000 meters or so off the track of your target at periscope depth with your submarine's bow pointing towards the target's track at an angle of precisely NINETY DEGREES (plus or minus less than one degree). Your goal is to be there and stopped at least 5 minutes before the target crosses your bow.

Often when I'm cruising on the surface my lookout will call out a contact some distance away. I use my watch officer to give me a range and bearing, start my stopwatch and plot the target's position on the map. Three minutes and fifteen seconds later, I ask my watch officer for another fix, dive to periscope depth, and again plot the fix on the map. I connect the two marks with a line and extend it some distance beyond my position. I now have the target's position and course (leave the stopwatch running). Then I measure the distance between the two marks. Because I measured the targets position at an interval of three minutes and fifteen seconds, the distance in kilometers divided by ten equals the target's speed in knots. If you are worried about being detected on the surface, try measuring for one minute and five seconds (and multiplying by three to get the target's speed) or two minutes and ten seconds (and multiplying by one point five to get the target's speed).

In less than five minutes from initial contact one can determine the target's position, course and speed. We now have all the necessary information to complete our attack with surgical precision (I love that phrase. Can you tell?).

From this point onwards we need only keep track of the target's bearing via hydrophone to determine how much time we have left before we shoot.

Turn your submarine towards your target's projected track line. Use the protractor tool to measure a right angle between your position and the target's projected track line. Align your course so it intercepts the target's track line at PRECISELY NINETY DEGREES.

Use the compass tool to draw a two thousand meter circle centered on the intercept between your track and the target's track line. Order all stop before you arrive at the edge of the circle and drift so your submarine is motionless at between eighteen hundred and twenty two hundred meters from the target's track (this distance need not be precise. This distance simply gives a nice sight picture in the periscope).

Why are we performing such precise maneuvers when we could simply enter data into the TDC and shooting from that any position we like?

Answer: In all firing solutions except where the torpedo gyro angle is zero one must determine the target's precise range in order to compensate for the distance between the torpedo tube and the periscope (some 100 feet or so). When the torpedo turns, the TDC must compensate for this distance or the torpedo will simply miss it's mark by this same distance (100 feet) on top of any other errors resulting from inaccurate determinations of speed or AOB.

The difference between the course of the torpedo and the bearing to the target as seen through the periscope increases as the target's bearing approaches 90 degrees port or starboard, and decreases as the range to the target increases. But if the torpedo doesn't need to turn at all to reach the target, then the TDC does not need to compensate for the distance between the periscope and the torpedo tube, and the range to the target becomes irrelevant. Plus, by positioning ourselves ahead of the target, we can eliminate the error form imprecise AOB measurements by entering a precise AOB that we know the target will reach at some point in the future.

The law of sines takes over and as long one enters the correct AOB and speed into the TDC, and the target is within the torpedo's effective range, then the fish will hit whatever part of the target happens to be under the periscope wire, with precision. This only happens however if the target is on the centerline of your submarine when the torpedoes arrive.

And here is how we make that happen:

I'm going to assume you are using OLC Gold here. If you are not, download it and install it. It's awesome. Otherwise, simply be aware of how to switch your TDC computer from manual to auto and back.

While you are on your way to your shooting position, go to the periscope screen. Select each torpedo tube one by one, open its door, set depth to zero, impact pistol, and select a torpedo speed. I prefer impact pistols unless the water is very calm. If you use magnetic pistols remember to select an appropriate depth (one meter below the target's keel). Make sure the speed you select is the same for every torpedo you intend to shoot. Again make sure each of your torpedo doors are open (hit Q as you select each tube).

Raise the periscope slightly (don't pierce the surface) and set its bearing to zero. Open the TDC panel (select manual TDC) and set the AOB to precisely NINETY DEGREES port or starboard as the situation dictates (if the target will pass from starboard to port, then set AOB to red (port) ninety degrees). Don't worry about the target's current AOB. We are selecting precise AOB that we know will be correct at some point in the future (when the target crosses the projected centerline of our submarine). Enter the target's speed (calculated above) into the TDC computer. I like to set the range dial to my approximate distance from the target's track, but it's not necessary by any means.

Without moving the periscope, close the TDC panel (select auto TDC). Now turn the periscope until the gyro angle (digital readout in the periscope station) reads 000. Leave the periscope pointed there and note the bearing in the viewfinder.

Use the hydrophone to track the target's approach. When the target is about fifteen degrees from the bearing noted above raise the periscope. Without changing the periscope's bearing, wait for the target to cross the vertical crosshair.

Shoot when the target passes under the crosshair. The torpedoes will impact whatever part of the ship was underneath the crosshair at the moment the fire button was depressed; hence the term "surgical precision." Aim for the engine room and other juicy bits.

Once your torpedos are away, you can either dive to evade escorts or turn your periscope to bearing 000 and watch your torpedoes impact.



This technique is really easy and intuitive once you understand the basic concept. And the precision it affords will make any other style of attack seem like common butchery.


Cheers, and good hunting.

I've intercepted single ships using hydrophones before, Generally I try and keep it about 80 degrees bearing off my bows until it gets within medium range, then I just sit with the scope up, at 2X time compression, soon as the target's visible the TC resets to 1x and I scan with the scope untill I pick it out. Adjust my direction so it'll cross my bows at around 90 degrees aob, set torpedoes accordingly and either move back or forward as required for a point blank shot around 300-500 meters.
Last time I tried this on a convoy though I lost my boat. Sank a troop ship and was just lining up on the shadow of the ship behind it when I got run over by an oil tanker! :P

Yep with the rewards of penetrating convoy formations come and the risks.

I've had a bad feeling all along about this patrol - now I'm heading home, albeit slowly , hoping to spend my last torps on route.

But I have had to admit my computer can't run GWX3 very well - it's fine other than when I zoom into the 5km and 2.5km maps and then the stutter gets very bad. It ruins the experience for me.

I don't remember that happening with 1.3, which I have somewhere, so I'm going to load that back up. I'll maybe try 2 or 2.1 as well to see if I can mange that.

Such a shame. Oh well, I'm sure I'll be back on the water soon.

Skookum, thanks for the help mate; I'll have a closer look at that soon :up:

A few points about accuracy:

IIRC, the weapons officer give ranges only to the nearest 100 metres. So, any range you get from him could be out by as much as 50 meters. For the two readings you suggest, that's a possible cumulative error of 100 metres. At 2000m range, that a 5% error. This 5% error in total range gives an angular course error range that varies inversely with target speed. At 6 knots, target will travel about 600 metres in 3:15. The angular course error in this case is arcsin(100/600) = 9.59 degrees.

Measuring once every 1:05 triples the possible error.

Furthermore, using 3:15 is only an approximation. It introduces a further error of about 1/2%. 3:14 gives a more precise speed measurement.

For more accurate results, take several readings 3:14 apart, total them and divide by one less then the number of readings. Especially if you are using stadimeter readings rather than WO reports, it is also helpful to compare the various individual readings and account for anomalies amongst them.

IRL, kaleuns would observe a target for quite a long time (over several kilometres) to be satisfied they had correct course and speed info.

I'm not a big fan of setting torpedo depth to 0 unless the sea is dead calm. IRL, a torpedo breaching the surface would often get thrown off course.

Depth below keel for magnetic detonators should probably be increased a bit in less than calm seas.

When firing magnetics, you might want to set up a shot that impacts the target at an angle much less than 90 degrees. You do this by changing the angle between your course and the target's course to the angle you want the torpedo to intersect him at. You can still get a 0 gyro angle shot.

Indeed you are correct. There are inaccuracies in this teqhnique.

However, since the compass tool only gives measurements to the nearest 100 meters anyways we have to do what we can without making the process too complicated for busy kaeleuns.

The angular track error introduced by using fixes taken only three minutes and fifteen seconds apart really only means that the target's range at impact will be off some, and that the AOB will be off slightly too. Both of these errors are mitigated by shooting the fish at a gyro angle of 000. Sure, a six degree track error over ten kilometers means the target will be closer or farther away from your U-boat by 1000 meters. In my experience however the error is usually much less. Since the target's range at impact makes no difference to the firing solution at a gyro angle of 000, accurately measuring the target's speed is therefore more important. Again, in my experience, the nice round 3:15 rule gives me speed measurements accurate enough to choose, at will, the parts of the ship that I hit. I do take the time to confirm the targets speed as it approaches by using the OLC Gold stopwatch.

Of course, real kaeleuns may have stayed on the surface for hours analyzing target speeds and courses from a distance. A target approaching a moving U-boat from the bow in SH3 however will begin avoidance maneuvers very quickly, even in good weather, making an accurate shot very difficult.
The best bet is to get two quick fixes, dive, and mitigate the inaccuracies using the techniques described above.

This is not modeled in SH3.

Good Call.

While the line drawing tool only gives lengths in multiples of 100 metres, if you take into account the fact that it changes its length readout at the 50 metre mark, you can easily draw a line length accurate within 30m.

If you make a 50 metre error at each measurement, then you can get a speed measurement error of 1 knot, which is enough to induce a miss with slow torpedos.

Two 30 metre errors probably will not cause an miss, if you set target's speed in 0.5 knot increments, but could if you only measure target speed in whole knot increments.

When you add the error due to WO round-off to the error from using 3:15 instead of 3:14, the error in AOB can be greater than 10 degrees.

For this maximum error to occur, target course needs to be perpendicular to target heading with AOB close to 90.
In such a case, maximal angular error is only about 1 degree, or just over 5% at 2000m range.

Coupled with possible plotting error of 60 metres this gives a possible error in speed of 1 knot. Again, enough to miss with a slow torpedo. Adding just a single additonal reading 3:14 later cuts the maximum possible speed error in half, and half the time reduces it to less than 1/4 knot.

Well, yes, but how much? I've been trying to figure out what the torpedo course error is going to be when your AOB is off by 10 degrees. I'll edit this post if and when I get an answer.

Well, if you are measuring during the time target travels 10km of course error will be much less. Calculated error in this case will probably be negligable. But you are suggesting a method which allows a ten degree track error over 600 metres.

Right.

As shown above, plotting error and angular error over a single pair of readings can be enough to miss. With a third reading, error should be too small to miss.

The one second difference will not make a significant difference in measured speed, but it can make a 1/2 degree error in course.

I'd rather suggest taking several more readings from farther away to get better data, and then move in to intercept. Relying on only two quick fixes is too likely to result in a miss. I'll post more data when I've made the calculations, which may need to wait a couple of days.

Personally, I love convoy attacks in bad weather.

Sure, it can be hard to spot and ID your targets, but the escorts have a much harder time finding you too. You can get away with alot more at periscope depth in bad weather (even surfaced) than you can in good weather....... and I've even made many escapes at PD too. Once you dive any deeper they've got you in their sights.

Mind you, if they start pinging you hard......... dive deep and run away.

Funny thing about enemy radar later in the war - it actually helps you find the convoys....

@ RoaldLarsen

Not to sound snooty but I don't understand why you're picking this tactic to pieces. It gives me hit percentages in the high nineties. I usually can't choose which rivet I want to hit, but I get to pick the compartment I hit.

I think you're missing the point of the 90 degree engagement at 000 gyro angle.

The whole point of shooting from a right angle to the target's track, aside from guaranteeing a detonation with impact pistols, is that you can get away with the target's AOB being off some (yes, even ten degrees) without wondering if the torpedoes will hit. I do it often. I don't know what the exact figures are but I don't care because it doesn't affect my hit percentages.

With a gyro angle of 000, pure trigonometry dictates that no matter what the target's range is, as long as the predicted speed is reasonably accurate, and the target's course is roughly as predicted, that the torpedoes will hit. Doesn't matter if I thought the target was at 1,200 metres and it ends up being at 4,000 meters when I launch. The fish still meet their mark.

Very useful when simultaneously engaging convoy targets in different columns.

And in my experience, the 3:15 rule gives speed and track information accurate enough to just about guarantee a hit every time. Again, the less time I spend on the surface, the less likely my target will evade.

If you get convoy intel and intercept 150 kilometers ahead of the mark you made on the map, then you have a very accurate course prediction. If you noted the time of the intel too, then there's your speed.

I don't have the time on a busy convoy intercept, while engaging multiple targets on one pass, measure the precise range and set the tdc for every singe target. All the ships travel in the same direction at the same speed which is an ideal situation for this tactic.

I just sit there and let the ships sail into the kill zone on their own so I can pick them off at will. No mess, no fuss.

Hell, you don't even have to be stationary. As long as your course stays constant, you can move at any speed and still hit everything that crosses the wire.

All I need to know that when I launch a fish, that the ship under the wire will go to the bottom.

This technique lets me do that almost every time.

From my experience it's very hard to get true target's course in just 3.15 minutes. Two plots aren't enough. Sure, if I'm less than 1000m from a long target I will probably hit him allright, but shooting from a longer distance I'd call risky.

Skookum, I'm hoping to try your method out on my current patrol, regardless of whether I encounter bad weather or not.

I've reinstalled with 2.1, and my computer is handling it better than 3.0.

On my first patrol I've so far sank four ships for around 20 tonnes with 6 torps. So another one or two ships would be good, then I'll try your suggestion.

Good luck, and happy hunting! Oh, and don't forget to try OLC's GUI. It's sweet!

What are you sinking...liferafts? :hmmm: :DL