Bad Weather Convoys

[Nerazzurri]

Because I've just came back to the game after a while I want to know what you guys would do in this situation.

1939, 15m/s winds and rain and the associated waves and low visibility; convoy's approaching Britain, just off Ireland, slow moving, with what appears to be just one escort.

If it was open ocean I'd like to shadow the convoy. But with not far for it to reach it's destination there's not really any point, i don't think. And the chances of getting off a successful shot are very small, I think.

Would you's leave it alone, and if not, what would you do?? :doh:

[BulSoldier]

I am actually quite unlucky in my current patrol. It is late january '40 and it is just neverending massive rainstorm. IN day i have some visibility but at night iut is so dark that the watch crew noticed large convoy at 400meters (i was actually within the convoy and they were traveling opposite to my course). I dived and creeped away.It was plane luck not to ram a ship.

It was poitless trying an attack since even at 400meters from the closest target i couldnt see it.My best advice is whenever the weather is making your calculations hard you better just leave the convoy until there are more favorable conditions.
It is just not worth the risk shooting torps in such a hard conditions.There is always the next convoy, but when you are on patrol you cant just find torps floating around to rearm if you keep wasting your aals at hard targets.

[sharkbit]

Are you sure about the one escort? And by low visibility, I assume you mean the weather report reads no visibility(<1000m)?
If it is 0 visibility(<1000m) I'd be tempted to try a surface attack and run like a madman through the convoy taking snap shots with gun and/or torpedoes when a target presents itself and pray that there isn't a Southampton Class cruiser in the middle of the convoy that sights you when you emerge from the mist.:o

Lightly escorted convoys are just too hard to pass up, even in crappy weather.
:)

[mr chris]

I'd be tempted to try a surface attack and run like a madman through the convoy taking snap shots with gun and/or torpedoes when a target presents itself and pray that there isn't a Southampton Class cruiser in the middle of the convoy that sights you when you emerge from the mist.:o



Well it is funny you should bring up a Southampton Class cruiser.
As in my last patrol mid 1940 400km east of Ireland. I blundered into the middle of a convoy in heavy fog. I only noticed i was in the middle of one when decided to take some air on the bridge. I was presented to my horror, a Large cruiser popping out of the fog right in front of my boat. No more than 400m away. :o:o:dead::dead:
I hit cash dive so hard i thought i had broken the keyboard.
I managed to avoid being seen. I have no idea how the cruisers lookouts must have been sleeping on duty.
I set course to slowly slink away.
Then went up stairs to change my underwear.;)

[Packerton]

I saw Shadow it, or simply pick some targets in the center (usually the biggest ones) and use your hydrophones to hit that one.

[Jimbuna]

BE MORE AGGRESSIVE!!...SINK EM ALL!! http://www.psionguild.org/forums/images/smilies/wolfsmilies/pirate.gif

[Nerazzurri]

BulSoldier, I think I agree with you mate - better to leave it alone.

Sharkbit, I'm not sure about the one escort - about 80% certain. The visibility is about 400 metres. So even if I do go in on the surface I might just end up fizzing torps everywhere as I wouldn't have enough time to actually target anything. And with waves this size I just don't know how to approach the pistol settings anyway - ships bobbing around like corks.

Jimbuna, I might be more aggressive - tomorrow :cool:

[sharkbit]

I posted a similar question about attacking a convoy in piss poor weather a while ago and the funniest replies in the thread was:

"Think of all the other Kaleuns back in port, s******ing at you behind your back.

"Oh, look, it's Kaleun Loser..."
"The one who only hunts in good weather!"
"Perhaps he should ask for a transfer...to the carribbean?"
"As if the rest of us don't have the same problems..."
"Did you hear, Churchill sailed an entire armada to Gibraltar but 'Herr Kaleun' here couldn't see it well enough to take a shot?"
[imitates] "Ah well, never mind about the boys in the luftwaffe who'll take the sharp end of all those bullets... another convoy'll be along shortly."

Give it a shot. Sure you'll miss a few, but that's life (and North Atlantic weather) for ya! Better shoot off your eels, miss and blame the weather than make an example of giving up in front of your crew. "

I had to LOL :haha:

[Paul Riley]

If low vis is really bad there isnt much point in trying to get ahead of the convoy and intercepting it by the book,your best bet would be to race into the convoy itself at night on the surface (ideally with decks awash,7-8m),preferably from the rear keeping your bow towards them as much as possible to lower your silhouette,and fiercely attack from within,as you will be at close range and able to properly steer the UBoat towards your chosen target/s.Still,a very risky affair.

You are fortunate its only 1939,the escorts will be minimal and poorly experienced at this point,wait until you hit late 1942,and radar is your greatest enemy,not the weather.

If in doubt,leave it

[Nerazzurri]

Sharkbit, very good. The comment about the crew makes sense, in an immersion sense; but to play devils advocate, what would they think if I went in and wasted a handful of torps when I could save them for more favourable conditions?

PRiley, the conditions you mention were the plan I was considering, but I'm just not cofident with torpedoes in that position. From behind you'd need to use magnetics, not an easy thing to do with ships bouncing meteres up and down. And in low visibility, by the time you spot a target, and turn to get a reasonable gyroangle, you're under the torps minimum range :stare:

In the end I left it and turned away. Luckily I ran into slightly better weather the next day - so it worked out OK.

[Paul Riley]

Probably the wisest thing to do,the odds I think were too high against you,and if not overly confident in the first place would only exacberate the problem.UBoat commanders tried desperately to change conditions in their own favour,but I reckon in some situations the best course of action would be to abort,and try elsewhere.Better than a complete waste of torpedoes in conditions that are not ideal for UBoats,unpredictability of the high waves to mention but one,and bad visibility.

Good luck elsewhere.

[skookum]

I've successfully attacked convoys in poor visibility using the hydrophone and some intel. If I get a contact report on a convoy, I plot my intercept as usual to arrive about 30 miles ahead of the group. I do my best to line up with my bow 90 degrees to the convoy's predicted course and about 2000 meters off the center line. With the periscope pointed at zero degrees I input the convoy's predicted speed and AOB (90 degrees) into the TDC and then switch to auto TDC. Then I set my torpedo gyro angle to zero by turning the periscope to the appropriate bearing. I make a note of that bearing and plot it on the map from my boat's position. I simply launch a fish or two each time a hydrophone contact line crosses the bearing line. Because the gyro angle is zero the range to the target is irrelevant and I get a hit more often than not. It's impossible to perform the surgical precision that one can achieve with a visible target, I often have no idea what ships I hit until they show up in my patrol log, and I rarely get to watch my prey go down. But it certainly makes foggy days less bleak. It's pretty exciting watching the stopwatch count off the seconds to impact.

[Paul Riley]

Interesting tactic

[Nerazzurri]

Skookum, that sounds beyong my ability (I don't use manual targeting :oops:), but I'm going to give that idea some thought, because it sounds quite good.

[Paul Riley]

We all had and still have problems sometimes with manual targetting,not to mention awkward attacking conditions.
Give it a try sometime,there is loads of info in here about just about anything,not to mention the amount of brain cells pumping away in this forum day and night!
Myself,I have played this game since its release,and the other day I made a terrible error,and missed at only 500m with an electric torpedo :nope:

[Nerazzurri]

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.

[skookum]

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.

[Bronzewing]

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

[BulSoldier]

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

[Nerazzurri]

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:

[RoaldLarsen]

[a whole bunch of good stuff] ... 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?).

... [more good stuff]


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.

[skookum]

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.

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.

This is not modeled in SH3.

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.

Good Call.

[RoaldLarsen]

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.

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.

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. 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.

Both of these errors are mitigated by shooting the fish at a gyro angle of 000. 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.

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.

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.

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.

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.

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

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.
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.

[d@rk51d3]

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.

[Leandros]

If low vis is really bad there isnt much point in trying to get ahead of the convoy and intercepting it by the book,your best bet would be to race into the convoy itself at night on the surface (ideally with decks awash,7-8m),preferably from the rear keeping your bow towards them as much as possible to lower your silhouette,and fiercely attack from within,as you will be at close range and able to properly steer the UBoat towards your chosen target/s.Still,a very risky affair.

You are fortunate its only 1939,the escorts will be minimal and poorly experienced at this point,wait until you hit late 1942,and radar is your greatest enemy,not the weather.

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

[skookum]

@ 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.

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.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.

[Kubryk]

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.

[Nerazzurri]

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.

[skookum]

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

[Jimbuna]

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.

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

[Nerazzurri]

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

Doh! 20, 000 tonnes :88)

p.s. no, I machine gun the liferafts :arrgh!:

[Jimbuna]

Doh! 20, 000 tonnes :88)

p.s. no, I machine gun the liferafts :arrgh!:

If you ever manage to sink one let me know :DL

[RoaldLarsen]

@ RoaldLarsen

Not to sound snooty but I don't understand why you're picking this tactic to pieces.Hmm. I didn't think I was picking it to pieces, just quibbling with some details. What you descrbe is a good general approach for sinking tonnage in the game and I just think it would be much better with another WO reading.

I'm going through this for two main reasons.

1) I'm a bit of a fanatic about simulation, and the method you describe was not usually employed, AFAICT.

2) I think it is possible you are overstating the adequacy of this technique.

In fact, I think this will work well enough much of the time, but I want people to be aware of the inherent inaccuracy of one pair of measurements 3:15 apart, in case they think this will do them for all their shots.

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.You keep statistics of all your torpedo shots? Please tell me you have statisitics for on the order of 10,000 shots, otherwise you can't claim with any validty that it is your method that is giving you the claimed hit percentage. It could just be statistical variance of the cumulative error of the WO reports.

I think you're missing the point of the 90 degree engagement at 000 gyro angle.
Nope. That's why I waited to do some calculations before I made this post. I realized that the 0 gyro angle shot at close to 90 degrees to target track would not be nearly as sensitive to course measurement error than non-zero gyro angle shots. But I didn't know how much.


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.
Well, I expect that they do affect your hit probabilities, but you haven't noticed. Relying on a single pair of readings 3:15 apart, in a scenario like the one you described can increase your inaccuracy above the inaccuracy expected due to plotting error by 33%. Take three readings, spead over 6:30 and the increase in inaccuracy is only 10%. Does this really matter? If most of your shots are taken at large targets at ranges under 1km, probably not. From the scenario you described, I assumed otherwise.

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.
I agree. So how accurate do you need to be with course and speed before you run into problems?

I ran the numbers for the following situation:
Submarine remains motionless throughout, except to pivot.
Submarine is 1750m from target's actual track.
Target starts 2450m away. (Bearing 46 degrees)
Target speed is 6 knots.
Assume no plotting errors or bearing errors.
You get bearing and range from WO, with range short by 50m from actual, due to rounding.
After 3:15 your get bearing and range again, this time with range long by 50m.
This gives you an observed target speed of 5 knots (nearest whole knot multiple), and an observed target course 8 degrees away from true course.
You rotate to perpendicular to observed course, and fire an electric torpedo when target comes on bearing for 0 gyro angle shot.
You miss the aiming point by 20m, but because there are no other errors, you still hit the target.

Now add in median error due to plotting inaccuracy and bearing precision limits. That 20m error factor is enough to change many shots from hits to misses.

Repeat the scenario except this time take your second reading after 6:30. This time you miss the aiming point by only 6.5m. This is not a signifcant change to the overall inaccuracy from plot and bearing error.

I can't give an exact figure for the difference in hit percentage because there are too many variables: range, initial bearing, target length, target speed...

What I can say is that determining target speed and course from only two readings 3:15 apart can have a significant impact on your miss rate, while adding a third reading after another 3:15 reduces the impact to insignificance.

With that one simple refinement to what you proposed, I think it is a great approach to attacking.

[evan82]

If we have some "good eye" skills, and we play with manual targeting, and our u-boat is in the good attack position alredy [usually 350m - 1500m from target with AOB from about 60 - 110 degree] then we can use periscope as a
hind-side. First we set periscope for bearing 0, then in TDC manually AOB for 0, range for 700m - 800m, and target speed for 0, and after this we push the automatic update button for the "ON" [red setting]. From this time we can use center of periscope as a hind-side. This is very good method when we dont have time for update TDC.

For example. If torpedo speed is 30 kt and we attack C2 which is about 600m from us then we move center of the periscope [on 1x zoom] on the position: about a half lenght of the C2 cargo before C2 cargo and we fire torpeedo. If we have some experience in this then we have very powerfull tactic for some situations.:DL

You must feel the target speed

[Tozzifan]

skookum, thanks!

I've tried your method: 8 torpedoes of 8 on target

I'm not an expert, at all, and maybe there are better ways to sink merchants, nonetheless seing my hits percentage raising from 20% to 100%, makes me a lot thankful :woot:

[gordonmull]

One technique in bad weather is to take advantage of the convoy's formation.

Get into the middle of at least the first two lanes and cruise backwards until you've got one coming across for a shot from the rear tube at as near to 90 deg AOB as possible. If it gets too close, abandon this shot, if not take it. At the same time fire two eels on a 1 deg spread out into the fog on 0 deg gyro angle shot from the front tubes. If you hit you're rear target you're almost assured of a hit on your front target with both eels.

Personally, at this stage I also take a bit of a random shot about 10 deg (not precisely!) either side of 0 gyro angle in the hope of hitting something else. The random shots do sometimes pay off.

[Tozzifan]

One technique in bad weather is to take advantage of the convoy's formation.

Get into the middle of at least the first two lanes and cruise backwards until you've got one coming across for a shot from the rear tube at as near to 90 deg AOB as possible. If it gets too close, abandon this shot, if not take it. At the same time fire two eels on a 1 deg spread out into the fog on 0 deg gyro angle shot from the front tubes. If you hit you're rear target you're almost assured of a hit on your front target with both eels.

Personally, at this stage I also take a bit of a random shot about 10 deg (not precisely!) either side of 0 gyro angle in the hope of hitting something else. The random shots do sometimes pay off.

cannot this tecnique be used in calm weather ? (I mean, standing still at depth and waiting for the convoy)

too high risk of detection?

[Subcutaneous]

Here's what I don't get about this technique. If you point the sub perpendicular to the target track, the AOB isn't going to be 90 degrees at the time gyroangle is 0, unless the ship is stopped.


.....|--d--|
..ship------------------>
......\ A..|
.......\...|
........\..| <-Torpedo track gryoangle 0
.........\.|
...........^
..........sub

Angle A is the AOB for that ship, d is the distance the ship will move between torpedo launch and interception of the target track. Am I missing something?

[vorosgy]

Here's what I don't get about this technique. If you point the sub perpendicular to the target track, the AOB isn't going to be 90 degrees at the time gyroangle is 0, unless the ship is stopped.

Yes, you are correct, the AOB will not be 90 degrees, but that is no problem.

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.

When you enter the AOB 90 degrees, you are looking precisely forward. By closing the TDC panel (thus setting the TDC to automatic mode), the TDC will continue to automatically update AOB according to your looking direction.

So what you really enter in the TDC is that the target AOB will be 90 degrees, when it reaches bearing zero.

[meduza]

@Subcutaneous

You're not missing anything. :DL When you launch a torpedo, AOB is not 90, but when it hits, it will be (that is if you launched at perpendicular course, 0 gyro angle).

[Subcutaneous]

By closing the TDC panel (thus setting the TDC to automatic mode), the TDC will continue to automatically update AOB according to your looking direction.


This was the part that eluded me...as I was driving to work I suddenly realized I had forgotten about this aspect of the TDC. Once the TDC understands the target track, it's flexible about where the target actually is on that track.

I did come up with this adjustment though: I don't think you actually have to be perpendicular to the track, although I realize it helps the impact detonators. One could use the protractor to calculate the AOB from the target track easily enough, no? Click on the sub, then click on the point where the sub's heading line intersects the track, then anywhere on the track back toward the target. Tweak the resulting angle for your relative position to the target (in front, behind, port, starboard).