How critical is AOB in solution?

[Galanti]

I'm trying full manual targetting with the Assisted Plotting mod, and am finding my fish are missing by a wide margin. In one case, my spread went out on a course well aft of where the target was at the time of launch!

I'm trying to track down what's going wrong, and the only thing I can think of is massive errors in the AOB inputs. Speed seems right, and range is constantly checked and rechecked using the stad and measuring distance using the map.

So I think the only thing left is AOB, but it doesn't seem that off to me. So what kind of a difference can say 20-30 degrees make, at ranges around 2500 yards and 8 knots of speed? I mean, my torpedoes are way, way off.

[AVGWarhawk]

Missing which way? I often find the AOB does not have to be exact. It is speed calculation that screws me up. This is the hardest to get accurate and really is the most important piece of the puzzle.

[McBeck]

Did you open your torpedo doors before making the shot?

The longer you are away from you target the more important your estimates are.

If you are 300-600 yards from target 10 degrees off wouldnt make much difference I think...

[AVGWarhawk]

Did you open your torpedo doors before making the shot?

The longer you are away from you target the more important your estimates are.

If you are 300-600 yards from target 10 degrees off wouldnt make much difference I think...

True, the closer you are the small miscalculations usually don't affect the outcome you are looking for.

[PopManiac]

Missing which way? I often find the AOB does not have to be exact. It is speed calculation that screws me up. This is the hardest to get accurate and really is the most important piece of the puzzle.

At the risk of spamming, cause I mention the same thing elsewhere, can you recommend any tutorial for speed calculation, besides the one made by Hitman?

Preferably something that does not take one away from periscope cause the clumsy game interface is quite convenient to be moving to map, taking measures and then back to scope...

[AVGWarhawk]

Sorry, Pop, I do not have any and have never watched a tutorial on speed calc. I'm a in your face Skipper, I get so close if I'm off a kt or two it does not matter. Plus I 'm good at guessing.

[McBeck]

Missing which way? I often find the AOB does not have to be exact. It is speed calculation that screws me up. This is the hardest to get accurate and really is the most important piece of the puzzle.
At the risk of spamming, cause I mention the same thing elsewhere, can you recommend any tutorial for speed calculation, besides the one made by Hitman?

Preferably something that does not take one away from periscope cause the clumsy game interface is quite convenient to be moving to map, taking measures and then back to scope...
What about the infamous 3:15 method...I cant remember how its done other than you plot the length the ship travels in 3 min and 15 sec. Some very easy calculation then gives you a very excact speed...

[McBeck]

Just found this
http://www.subsim.com/radioroom/showthread.php?t=113649

Might help you ALL out ;)

[TopCat]

Missing which way? I often find the AOB does not have to be exact. It is speed calculation that screws me up. This is the hardest to get accurate and really is the most important piece of the puzzle.
At the risk of spamming, cause I mention the same thing elsewhere, can you recommend any tutorial for speed calculation, besides the one made by Hitman?

Preferably something that does not take one away from periscope cause the clumsy game interface is quite convenient to be moving to map, taking measures and then back to scope...
What about the infamous 3:15 method...I cant remember how its done other than you plot the length the ship travels in 3 min and 15 sec. Some very easy calculation then gives you a very excact speed...

Well, if you plot the ship's course you can read the distance. 1 kn is 0.51 m/s. in 3:15 the ship sails a distance of exactly 100 metres. So if you've got the exact distance in 3:15 (195 secs) and divide that by 100 you'll get the exact speed in knots.

Edit: Btw, as 3'15'' is a bit long, the more helpful way to go will be to plot the distance vor 20'' and divide by 10. Of course, this will be much less accurate because the errors in plotting the distances will have a huge effect on the results. It depends on the distance you are away from the target. The nearer the target is the less do any errors in distances matter.
The same thing with the AOB. On short distances errors in AOB do not have a great effect on the firing solution.

[AirborneTD]

I use a fairly simple and quick solution for speed similar in some ways to the 3:15 rule. You must have the nomograph mod installed or use calculations. When I am in visual range (with map contacts showing), I zoom in on the target ship, start the chronometer and then quickly make a mark at the bow of the target ship. I then advance the time compression to advance the clock to just after 4 minutes has passed. I go down to 1x compression and make a mark on the target at 5 minutes. I then use the nomograph (mod) on my map to plot the speed. Works quickly and accurately.
You can also use this method if you have radar to get the speed of your target or convoy before they even come into visual range. You can also extend out the time to 10 minutes or whatever for a more accurate plot.

For AOB, I guesstimate first and verify my plot by starting the Position Keeper and verifying on the attack map. I tweak as needed.

I play with most options on except for NO Map Contacts, External Views and Stabilized Views. I routinely bag over 60K tons of shipping per patrol.

May not be as challenging as having No Map contacts update, but I figure I've got a team of professionals working the plot with me so I really don't fret it.

[Hitman]

I'm trying full manual targetting with the Assisted Plotting mod, and am finding my fish are missing by a wide margin. In one case, my spread went out on a course well aft of where the target was at the time of launch!

I'm trying to track down what's going wrong, and the only thing I can think of is massive errors in the AOB inputs. Speed seems right, and range is constantly checked and rechecked using the stad and measuring distance using the map.

So I think the only thing left is AOB, but it doesn't seem that off to me. So what kind of a difference can say 20-30 degrees make, at ranges around 2500 yards and 8 knots of speed? I mean, my torpedoes are way, way off.


The AOB as AVG said does not need to be exact, however an exact AOB can allow you calculating speed very easily. From what you tell, I think it is speed the main problem you have. You can do this test to check that easily: Go to the navigation mission in the sub school and try to set up a solution for the T3 tanker that starts in front of you. Set a non-exact AOB and a speed of 9 (I think that's the speed the tanker travels) and start the position keeper. You will notice that despite the X mark going in a divergent course to the real location of the tanker, your torpedos would hit the real ship after going past the X, as they will remain paralell for some time. Now restart the mission, set an exact AOB but put a wrong speed, f.e. 12 knots. You will miss easily with your torpedoes now :down:


At the risk of spamming, cause I mention the same thing elsewhere, can you recommend any tutorial for speed calculation, besides the one made by Hitman?

Preferably something that does not take one away from periscope cause the clumsy game interface is quite convenient to be moving to map, taking measures and then back to scope...


One of the easiest methods is the one based on ship's length: Set your bow to point to the target (Or make all stop and have zero speed yourself) and measure with the chronomenter how many seconds the ship takes to get past your vertical scope mark. Divide the lentgh in metres or yards by the number of seconds, and you have already the speed in m/s or yds/s. Multiply by two and you have a rough speed result in knots. F.e. 4 metres or yards/second is something like 8 knots, 5 metres or yards/second is something like 10 knots and so on.

Also if you build a wiz wheel like the one discussed in the IS-WAS thread, you can have a very easy and exact speed measuring :up:

[Krupp]

Also if you build a wiz wheel like the one discussed in the IS-WAS thread, you can have a very easy and exact speed measuring :up:
I just made my first "by the book" attack using course finder and calculating speed with the speed omnimeter and bagged a heavy cruiser with four torps.:sunny: I'm so happy that I got this wonder tool at this point, when the game is still fresh.

[jetthelooter]

i have noticed that most of the shipping i run across the speed can be determined by a couple of methods. radio reports on TF and convoys tell the speed. for single ships and pairs and such they travel and 1/2 their listed max speed rounded down. if two ships of different types are together they travel at the faster ship's 1/2 speed rounded down.

if your spotted all bets are off as they can speed up slow down and zig zag at different speeds.

destroyers tend to travel at 15kts when going to a plane spotting. if a DD makes a visual on you and is headed right to your position it is always at 33kts until they close to 2000yds then they slow to 18kts and zig zag to avoid torpedoes.

when a DD returns to a convoy or TF it is always at their listed max speed.

after attacking a convoy some ships will speed up others will slow down and they will zig zag but not enough to make any difference in a torpedo solution if you fire a spread.

AOB only needs to be mostly right it is the least critical component speed and range are the most important. but the key to it is a correct ship ID. i spend most of my time making sure i have ID'd several targets correctly

[Chock]

AOB can be important at longer ranges, and this is apparent when you note that many of the famous US sub commanders and XOs would practice estimating AOB with models placed some distance away, which they would look at through binoculars the wrong way around.

If you estimate that your torpedo is going to take about a minute to travel 1500 yards (1552.7 to be exact, but 1500 is close enough for quick calculations), then a target travelling at eight knots is going to cover 270 yards in that time. Which gives you the deflection angle your torpedo is going to have to take into account on release in order to intercept it. But at a zero AOB, there would of course be no deflection to calculate, merely a 270 yard change in range. From this you can see that cocking up your AOB estimate could result in your torpedo being as much as 270 yards astern or ahead of the target. But of course nobody is going to confuse zero AOB with 90 AOB, so you probably aren't going to miss by that much. However, say you were off by ten percent in your AOB estimate; that would equate to missing your desired aim point by an average of 27 yards (could be either more, or less depending on the angle), and that's if your estimates of range and speed are spot on.

With regard to speed, if the target was travelling at seven knots rather than eight, it would cover approximately 35 yards less in one minute, and at nine knots, about 33 yards more. So a one knot miscalculation puts you out by about 34 yards either way. Add a ten percent mistake on AOB (27-ish yards), and you are looking at your torpedoes going ahead or astern of the target by approximately 62 yards (186 feet), which is roughly about half the length of an average freighter.

So from that we can see why real sub commanders would fire a spread, hopefully on overlapping or converging targets (which also covers the possibility of the target[s] taking evasive action). We can also see the value of opening the torpedo doors early to limit the delay between you pressing fire and the torpedo leaving the tube.

This is why getting close (less than 1000 yards) will increase your hit probability by a massive amount, as the difference in predicted positional errors for the target are far less.

[Galanti]

Thanks for all the input, guys. It seems clear that I may need to tighten up all the inputs. I know there are some issues with stadimeter readings, could this result in wild range fluctuations?

What worries me is that i am missing by literally a mile, and like I mentioned in one shot my torps immediately went well aft of the target, in which case I either must have dialled in a negative speed, or I can't tell ass from nose and pooched the AOB by 180 degrees!