Question about 4 bearing method against a convoy

PapaSmurf · 09-25-17, 11:37 PM

I am wanting some educated opinions about using the 4 bearing method when tracking a convoy. It's pretty straightforward against a lone target but depending on the size and range of a convoy the sound signature of a convoy can be 20 degrees wide or even more. With this in mind, how do you captains decide what the correct bearing is to use when doing your hydrophone checks? I have been trying to find the 2 edges of the merchant sound contacts and then using the center of those 2 readings as the bearing that I mark on the map. This obviously involves some guestimation and I was wondering if there is a better way to do this against convoys. I don't use escort sounds because they are twisting and turning enough to possibly mess up the works whereas the merchants pretty much stick to a set course. So how do you guys decide which bearing to record when using the 4 bearing method against a convoy?

B_K · 09-26-17, 01:07 AM

With sound, it is, if not impossible, at least very hard. With that high bearing spread your estimation is useless, unless you draw least and most possible area of probable courses. If you want to use 4 bearing method, maybe use periscope instead of sound, when possible. Bearings will be far more precise.

But in my opinion the best way (at least when escorts have no radar yet) is to overtake convoy while nearly outside visual range and use 0 bearing method (described in other topics) - simply you cross convoy's course while taking bearings at regular times and at max visual range - intersecting bearing lines taken while approaching with observed course lets you also know speed.

When you can't get within visual range, at least try by trial and error method to steer such a lead angle and speed that all contacts stay in the same bearing and closing - that means you are on a collision course which lets you approach a convoy.

Ausdampfverfahren method can also be then utilised.

Read here http://tvre.org/en/acquiring-torpedo-firing-data

derstosstrupp · 09-26-17, 07:20 AM

I agree it is difficult to use the 4-bearing method unless it's a single ship. In fact, I find the 4-bearing method difficult and time-consuming in general. My beef with it is that it requires you to lie stopped for an amount of time submerged, when in reality due to buoyancy concerns this just wasn't possible. If using Stiebler's patches, this also becomes difficult in-game - you'll sink slowly if you stop. Also, all that time spent for a course and speed may be dashed when the target changes course/speed. That a lot of lost time standing still when you could be moving to get ahead of the target to mitigate the effects of a course change.

With the Ausdampfverfahren I find you can get all the necessary information with a rough estimate of target AOB. Even better, I find (though I'm biased

) the methods in my tutorial in my signature below very effectively deliver what you need and closely parallel historical procedures as I understand them. The 0-AOB method you mention is the foundation of the tutorial. Ausdampfverfahren is included there, as is another method, "Auswanderungsverfahren", which allows for getting target speed using rough range and timing bearing change over 1 minute, while moving.

It's good to see mention being made of tvre.org - that man (God rest his soul) did some great work!

Pisces · 09-26-17, 09:51 AM

Taking the left and right edges of the sound bearing won't work (good enough) with hydrophone 'bearing only' methods. Especially if the convoy has an asymmetric layout. A convoy is almost never a perfect filled square or rectangle. Some units are missing. This could result in an off-center middle of the sound bearing. Skewing your bearings as it rotates around you. Making the resulting bearing plots more inaccurate to reality than it already is for a bearing of a single unit. If you must, use periscope as B_K suggested.

Or use trial and error homing. Move halfway your detection range along the center of the bearing. Break off to start plotting when you make visual contact. At the halfway-point dip down again for a sonar check. Repeat the process. You'll find it eventually and can start to make plots of a single member of the convoy.

Sorry every method has it's limits.

hauangua · 09-26-17, 10:12 AM

Quote:

Originally Posted by Pisces

Taking the left and right edges of the sound bearing won't work (good enough) with hydrophone 'bearing only' methods. Especially if the convoy has an asymmetric layout. A convoy is almost never a perfect filled square or rectangle. Some units are missing. This could result in an off-center middle of the sound bearing. Skewing your bearings as it rotates around you. Making the resulting bearing plots more inaccurate to reality than it already is for a bearing of a single unit. If you must, use periscope as B_K suggested.

Or use trial and error homing. Move halfway your detection range along the center of the bearing. Break off to start plotting when you make visual contact. At the halfway-point dip down again for a sonar check. Repeat the process. You'll find it eventually and can start to make plots of a single member of the convoy.

Sorry every method has it's limits.

Hi Pisces

You which method of intercepting uses?
(by hidrophone)
Four Bering?
Or?
Thanks

Pisces · 09-27-17, 03:17 PM

It's been a while since I played SH(3). But when I found a hydrophone contact I would take 3 bearings while stationary. Use my (prototype 3-bearing AOB calculator disc) to figure out the AOB and target course. Start sprinting away from my listening location. Direction depends on AOB at bearing 3; either along target course when AOB3 is past 90 degrees, or go perpendicular to bearing 3 when less than 90 degrees). In the mean time I use the plot to predict where a 4th (imaginary) bearing line would fall from the listening location. When the time interval is about to end I submerge to take a hydrophone check at a new location. Then the 4th bearing from my current location should intersect with the predicted 4th bearing nicely to locate the actual position of the target.

And I am patient! Bearing difference between 1st and 2nd bearing should be more than 5 degrees. If the bearings drift slow I record the time for each bearing 2 at 5, 6, 7, 8, degrees and so on. Then measure the 3rd bearing for each of those intervals until I judge when the AOB resolution is narrowed down sufficiently to within +/-5 degrees. And then it is as good as a target course given by a radio report.

I haven't mastered 'the 4-bearing method while moving' of Kuikeg (in SH4 or SH5 forum section) in practice. It's on my to-do list when I start playing the game again.

09-25-17, 11:37 PM	#1
PapaSmurf Bosun Join Date: Sep 2016 Location: On the front of a bass boat or in a deer stand Posts: 64 Downloads: 129 Uploads: 0	Question about 4 bearing method against a convoy I am wanting some educated opinions about using the 4 bearing method when tracking a convoy. It's pretty straightforward against a lone target but depending on the size and range of a convoy the sound signature of a convoy can be 20 degrees wide or even more. With this in mind, how do you captains decide what the correct bearing is to use when doing your hydrophone checks? I have been trying to find the 2 edges of the merchant sound contacts and then using the center of those 2 readings as the bearing that I mark on the map. This obviously involves some guestimation and I was wondering if there is a better way to do this against convoys. I don't use escort sounds because they are twisting and turning enough to possibly mess up the works whereas the merchants pretty much stick to a set course. So how do you guys decide which bearing to record when using the 4 bearing method against a convoy?

09-26-17, 07:20 AM	#3
derstosstrupp Grey Wolf Join Date: Aug 2008 Posts: 887 Downloads: 489 Uploads: 0	I agree it is difficult to use the 4-bearing method unless it's a single ship. In fact, I find the 4-bearing method difficult and time-consuming in general. My beef with it is that it requires you to lie stopped for an amount of time submerged, when in reality due to buoyancy concerns this just wasn't possible. If using Stiebler's patches, this also becomes difficult in-game - you'll sink slowly if you stop. Also, all that time spent for a course and speed may be dashed when the target changes course/speed. That a lot of lost time standing still when you could be moving to get ahead of the target to mitigate the effects of a course change. With the Ausdampfverfahren I find you can get all the necessary information with a rough estimate of target AOB. Even better, I find (though I'm biased ) the methods in my tutorial in my signature below very effectively deliver what you need and closely parallel historical procedures as I understand them. The 0-AOB method you mention is the foundation of the tutorial. Ausdampfverfahren is included there, as is another method, "Auswanderungsverfahren", which allows for getting target speed using rough range and timing bearing change over 1 minute, while moving. It's good to see mention being made of tvre.org - that man (God rest his soul) did some great work! __________________ Ask me anything about the Type VII or IX! One-Stop Targeting Shop: https://drive.google.com/drive/folde...WwBt-1vjW28JbO My YT Channel: https://www.youtube.com/channel/UCIJ...9FXbD3S2kgwdPQ

09-27-17, 03:17 PM	#6
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,892 Downloads: 300 Uploads: 0	It's been a while since I played SH(3). But when I found a hydrophone contact I would take 3 bearings while stationary. Use my (prototype 3-bearing AOB calculator disc) to figure out the AOB and target course. Start sprinting away from my listening location. Direction depends on AOB at bearing 3; either along target course when AOB3 is past 90 degrees, or go perpendicular to bearing 3 when less than 90 degrees). In the mean time I use the plot to predict where a 4th (imaginary) bearing line would fall from the listening location. When the time interval is about to end I submerge to take a hydrophone check at a new location. Then the 4th bearing from my current location should intersect with the predicted 4th bearing nicely to locate the actual position of the target. And I am patient! Bearing difference between 1st and 2nd bearing should be more than 5 degrees. If the bearings drift slow I record the time for each bearing 2 at 5, 6, 7, 8, degrees and so on. Then measure the 3rd bearing for each of those intervals until I judge when the AOB resolution is narrowed down sufficiently to within +/-5 degrees. And then it is as good as a target course given by a radio report. I haven't mastered 'the 4-bearing method while moving' of Kuikeg (in SH4 or SH5 forum section) in practice. It's on my to-do list when I start playing the game again. Last edited by Pisces; 09-27-17 at 03:44 PM.

09-26-17, 01:07 AM	#2
B_K Bosun Join Date: Nov 2011 Posts: 68 Downloads: 63 Uploads: 0	With sound, it is, if not impossible, at least very hard. With that high bearing spread your estimation is useless, unless you draw least and most possible area of probable courses. If you want to use 4 bearing method, maybe use periscope instead of sound, when possible. Bearings will be far more precise. But in my opinion the best way (at least when escorts have no radar yet) is to overtake convoy while nearly outside visual range and use 0 bearing method (described in other topics) - simply you cross convoy's course while taking bearings at regular times and at max visual range - intersecting bearing lines taken while approaching with observed course lets you also know speed. When you can't get within visual range, at least try by trial and error method to steer such a lead angle and speed that all contacts stay in the same bearing and closing - that means you are on a collision course which lets you approach a convoy. Ausdampfverfahren method can also be then utilised. Read here http://tvre.org/en/acquiring-torpedo-firing-data

09-26-17, 09:51 AM	#4
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,892 Downloads: 300 Uploads: 0	Taking the left and right edges of the sound bearing won't work (good enough) with hydrophone 'bearing only' methods. Especially if the convoy has an asymmetric layout. A convoy is almost never a perfect filled square or rectangle. Some units are missing. This could result in an off-center middle of the sound bearing. Skewing your bearings as it rotates around you. Making the resulting bearing plots more inaccurate to reality than it already is for a bearing of a single unit. If you must, use periscope as B_K suggested. Or use trial and error homing. Move halfway your detection range along the center of the bearing. Break off to start plotting when you make visual contact. At the halfway-point dip down again for a sonar check. Repeat the process. You'll find it eventually and can start to make plots of a single member of the convoy. Sorry every method has it's limits.