Noob Situational Question

unterseemann · 05-12-09, 04:31 AM

Welcome aboard,

You have a contact but you can't see it through the periscop, it's not a big problem.
The range for hydrophon is around 25-30km ( 50km for a convoy) , for the periscop it's less than 10km. Go to the hydrophon post and listen to it: if the sound is weak it means your contact is quite far so you can estimate the distance around 22-25km, it's not very accurate but you can now report its supposed position on the map ( you have a bearing and a distance).
Now you have to make a visual contact. What i do is running at the surface at full speed to the contact ( in your example you have a contact to your 047 so i turn 47° to the right) FOR 10min then periscop depth and listen to the hydrophon. Normally it should not be in your 0 anymore but in your 10 or 350 (and the sound is stronger) so you now have the target's global direction. What you have to do now is surface the boat and anticipate: It's important to have a visual contact but if you can be ahead of your target the attack will be easier. So if the contact is in your 350 set your uboat to 330, surface and run at full speed. If visual contact is not made just go to periscop depth and listen to the hydrophon again ( if you do this correctly you can't lose the hydrophon contact) Soon you will have a visual contact. Determinate the ship's course now is easy but i need some screenshots to explain it.

Keep on practice and if you need something you will find everything you want here as you may have noticed!

This is a basic approach for a single merchant with no escort, good weather, don't try this in 44' with a hunter-killer group in bad weather

Pisces · 05-12-09, 08:58 AM

I feel too tired right now to expand on it, but here is a tool that can help determine the AOB (and from that course) of a contact by bearings only:

http://www.subsim.com/radioroom/showthread.php?t=147719

You can use it in conjunction with the methods described in here, to get speed and distance:

http://www.subsim.com/radioroom/showthread.php?t=110619

There is also a thread in the SH4 section someone recently stated that figured out the same procedure:

http://www.subsim.com/radioroom/showthread.php?t=151526

This a more systematic approach, and takes some time to work out. It involves no guess work. The solutions provided here by the others also work (probably with quicker visual contact) but with more trial-and-error.

As a very simple solution you could do, just to get close, is to just move perpendicular to the direction of the target (put the sound on your 90 or 270 hydrophone), in the direction the bearing drifts (left or right). Since this is reported as a slow contact (less than 8 knots) you can likely manage to do this submerged. If it was faster (medium or fast merchant) you would probably have to surface and move fast. If you keep adjusting your course a bit towards him until this drift stops (sound stays on the same bearing for a long time) you are infact intercepting him (or aka collision course, so be carefull in the end). So you close the distance as fast as possible and maintain you position forward of him. If he was moving away this would have worked quite different. Meaning you can still adjust your course (almost in the direction of the target) until the bearing stops drifting, but you need to be alot quicker then him. Most likely needing to surface and flank, while regularly diving again to know how the bearing drifts. Also keep in mind then that the drift depends on the compass direction towards him, but the hydrophone direction changes as you turn the boat. The sum of your course and hydrophone bearing must stay constant.

If you just set your course to get the sound on the 90/270 direction only initially (so no course adjustments afterwards) then you actually move more forward of him,while he only does the work in closing the distance. It buys more time and distance ahead of him. The tough part is figuring out when you are on his course line and must stop to prepare for shooting. This would have to rely on making visual contact before then.

cueball7000 · 05-12-09, 09:00 AM

This was extremely helpful everyone. I can't wait to get back and try it out for real. Thank You.

Jimbuna · 05-12-09, 10:24 AM

Welcome aboard cueball7000

nikbear · 05-12-09, 10:28 AM

Welcome aboard CB7000,going in at the deep end eh!

Best of luck to you

Happy hunting

05-12-09, 04:31 AM	#1
unterseemann Soundman Join Date: May 2005 Location: lyon, france Posts: 144 Downloads: 53 Uploads: 0	Welcome aboard, You have a contact but you can't see it through the periscop, it's not a big problem. The range for hydrophon is around 25-30km ( 50km for a convoy) , for the periscop it's less than 10km. Go to the hydrophon post and listen to it: if the sound is weak it means your contact is quite far so you can estimate the distance around 22-25km, it's not very accurate but you can now report its supposed position on the map ( you have a bearing and a distance). Now you have to make a visual contact. What i do is running at the surface at full speed to the contact ( in your example you have a contact to your 047 so i turn 47° to the right) FOR 10min then periscop depth and listen to the hydrophon. Normally it should not be in your 0 anymore but in your 10 or 350 (and the sound is stronger) so you now have the target's global direction. What you have to do now is surface the boat and anticipate: It's important to have a visual contact but if you can be ahead of your target the attack will be easier. So if the contact is in your 350 set your uboat to 330, surface and run at full speed. If visual contact is not made just go to periscop depth and listen to the hydrophon again ( if you do this correctly you can't lose the hydrophon contact) Soon you will have a visual contact. Determinate the ship's course now is easy but i need some screenshots to explain it. Keep on practice and if you need something you will find everything you want here as you may have noticed! This is a basic approach for a single merchant with no escort, good weather, don't try this in 44' with a hunter-killer group in bad weather __________________

05-12-09, 08:58 AM	#2
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,904 Downloads: 304 Uploads: 0	I feel too tired right now to expand on it, but here is a tool that can help determine the AOB (and from that course) of a contact by bearings only: http://www.subsim.com/radioroom/showthread.php?t=147719 You can use it in conjunction with the methods described in here, to get speed and distance: http://www.subsim.com/radioroom/showthread.php?t=110619 There is also a thread in the SH4 section someone recently stated that figured out the same procedure: http://www.subsim.com/radioroom/showthread.php?t=151526 This a more systematic approach, and takes some time to work out. It involves no guess work. The solutions provided here by the others also work (probably with quicker visual contact) but with more trial-and-error. As a very simple solution you could do, just to get close, is to just move perpendicular to the direction of the target (put the sound on your 90 or 270 hydrophone), in the direction the bearing drifts (left or right). Since this is reported as a slow contact (less than 8 knots) you can likely manage to do this submerged. If it was faster (medium or fast merchant) you would probably have to surface and move fast. If you keep adjusting your course a bit towards him until this drift stops (sound stays on the same bearing for a long time) you are infact intercepting him (or aka collision course, so be carefull in the end). So you close the distance as fast as possible and maintain you position forward of him. If he was moving away this would have worked quite different. Meaning you can still adjust your course (almost in the direction of the target) until the bearing stops drifting, but you need to be alot quicker then him. Most likely needing to surface and flank, while regularly diving again to know how the bearing drifts. Also keep in mind then that the drift depends on the compass direction towards him, but the hydrophone direction changes as you turn the boat. The sum of your course and hydrophone bearing must stay constant. If you just set your course to get the sound on the 90/270 direction only initially (so no course adjustments afterwards) then you actually move more forward of him,while he only does the work in closing the distance. It buys more time and distance ahead of him. The tough part is figuring out when you are on his course line and must stop to prepare for shooting. This would have to rely on making visual contact before then. __________________ My site downloads: https://ricojansen.nl/downloads Last edited by Pisces; 05-12-09 at 09:37 AM.

05-12-09, 10:24 AM	#4
Jimbuna Chief of the Boat Join Date: Feb 2006 Location: 250 metres below the surface Posts: 191,014 Downloads: 63 Uploads: 13	Welcome aboard cueball7000 __________________ Wise men speak because they have something to say; Fools because they have to say something. Oh my God, not again!!

05-12-09, 10:28 AM	#5
nikbear Sea Lord Join Date: Feb 2007 Location: Northampton,UK Posts: 1,859 Downloads: 86 Uploads: 0	Welcome aboard CB7000,going in at the deep end eh! Best of luck to youHappy hunting __________________ 'It is not surely known when the grey wolf shall come upon the seat of the gods' Ericksmal.

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05-12-09, 09:00 AM	#3
cueball7000 Swabbie Join Date: May 2009 Posts: 6 Downloads: 59 Uploads: 0	This was extremely helpful everyone. I can't wait to get back and try it out for real. Thank You.