How to calculate Target Course

[Shelton]

Hi all

I am playing SH3 with map updates off so in the nav window I cannot see the target. Does anyone know how to calculate the target course given the following parameters?

1. Relative Bearing to Target
2. My uboat Heading
3. Angle on the Bow (of the target to uboat)

So just say
1 = 240 degrees
2 = 90
3 = 60 starboard

What is the ships/targets heading ?

Regards
Shelton.

[joegrundman]

EDIT--THESE MATHS ARE WRONG, SEE FURTHER DOWN FOR THE CORRECT SOLUTIONS!

OK, start with your heading. Add the periscope angle. Then add the AOB if it's starboard or subtract the AOB if it's port.

E.g.1. your heading 000, periscope angle 090, AOB starboard 90, target course =180
E.g.2 heading 055, scope angle 235, AOB port 25, target course = 055+235-25=290-25=265

In your example, 240, 90,starboard 60, target course =240+90+60=390=030

You can also draw it on the map using the protractor tool

But easiest of all is to build yourself a proper KM or US whiz wheel and solve the problem in seconds without ever having to think about it. You can also use it to plot a course that will give you the desired firing position

http://www.subsim.com/radioroom/showthread.php?t=114351&highlight=whiz+wheel

[ichso]

240 + 90 + 60 modulo 360 = 30°

But someone was still faster :)
For long range calculations you will need a more exact course than you get from rough AoB estimations.
So better make observations of the target's position relative to your own ones and mark them on the Nav map.

Then you can just read the target's course from there. You can then plan your attack so that the AoB is a very simple one, like 90°
See Wazoo's manual plotting tutorial - Fast 90° method (for example).

The Wiz Wheel should be the most historically accurate one though. At least for german submarines from that period.

[GoldenRivet]

i modestly submit my very first tutorial video.

this tutorial video instructs the viewer on how to plot solutions on paper using a ruler and protractor

it assumes the player already knows how to gather range to target, and understands headings and bearings

view it and PLEASE offer constructive critisism.

thanks!

http://hosted.filefront.com/GoldenRivet/

[joegrundman]

I may have been faster, but i was certainly wrong!

Actually i don't know hot to do it. Just build a whiz wheel. It's much easier :)

[Shelton]

Just watched the tutorial video - fantastic!! yes as you mention it becomes very difficult if my uboat is also moving - but i get the general idea - so there isn't a forumale i use to calculate the target course - other than plotting at different times?

[GoldenRivet]

plotting the target's position relative to your boat over time vs doing mathematic formula is probably easier - especially as far as visualisation - is probably easier

it is for me anyhow, of course everyone is different.

glad you liked it.

plotting the solution either requires a much larger sheet of paper or a much smaller scale on the ruler. but aside from plotting the target's position every couple of minutes you have to plot your own, including any turns you make etc.

edit: i should also mention the video only covers bow shots, unless you mark your bearings from 090 through 180 to 270 instead of the way shown (090 to 270 through 360)

[joegrundman]

Ok, there is a solution to do it. My wife and i worked this out over pancakes for breakfast.

Unfortunately it's kind of slow.

There are four situations you need to determine, and the equation is different for each.

1. AOB is port, and periscope angle is less than 180

Target course = heading + periscope angle + AOB -180


2. AOB is starboard, periscope angle less than 180

Target course = heading + 180 + periscope angle -AOB


3. AOB is port, and periscope angle is greater than 180

Target course = heading + periscope angle + AOB - 180


4. AOB is starboard, and periscope angle is greater than 180

Target course = heading + periscope angle - AOB -180

e.g. heading 240, scope angle 90, AOB starboard 60, use equation 2

240+ 180 + 90 - 60 = 090

Someone please check the solutions, right now i'm a bit surprised that equations 1 and 3 are the same. EDIT - I've tested them and they all seem to be correct

But you can see right away why the real submarines used a whiz wheel for this ;)

[Shelton]

OK, start with your heading. Add the periscope angle. Then add the AOB if it's starboard or subtract the AOB if it's port.

E.g.1. your heading 000, periscope angle 090, AOB starboard 90, target course =180
E.g.2 heading 055, scope angle 235, AOB port 25, target course = 055+235-25=290-25=265

In your example, 240, 90,starboard 60, target course =240+90+60=390=030

You can also draw it on the map using the protractor tool

But easiest of all is to build yourself a proper KM or US whiz wheel and solve the problem in seconds without ever having to think about it. You can also use it to plot a course that will give you the desired firing position

http://www.subsim.com/radioroom/showthread.php?t=114351&highlight=whiz+wheel

thanks for the tips and the link as well!

[joegrundman]

If you can't be troubled with making your own whiz wheel (I have made three, and the US ISWAS style is my favourite), the good news is that I am working on an electronic version of the KM whiz wheel that would appear in game. It's at a beta level now, it functions but not really well enough. However I am interested in having a playtester that could give me some constructive advice for it.

[Shelton]

Ok, there is a solution to do it. My wife and i worked this out over pancakes for breakfast.

Unfortunately it's kind of slow.

There are four situations you need to determine, and the equation is different for each.

1. AOB is port, and periscope angle is less than 180

Target course = heading + periscope angle + AOB -180


2. AOB is starboard, periscope angle less than 180

Target course = heading + 180 + periscope angle -AOB


3. AOB is port, and periscope angle is greater than 180

Target course = heading + periscope angle + AOB - 180


4. AOB is starboard, and periscope angle is greater than 180

Target course = heading + periscope angle - AOB -180

e.g. heading 240, scope angle 90, AOB starboard 60, use equation 2

240+ 180 + 90 - 60 = 090

Someone please check the solutions, right now i'm a bit surprised that equations 1 and 3 are the same. EDIT - I've tested them and they all seem to be correct

But you can see right away why the real submarines used a whiz wheel for this ;)

hey Joe thanks for this - i am going to use this next time i spot a merchant and try it out!

BTW YES your correct - the original equation on my first post - the merchant was indeed travelling 90deg !!!! so I was confused when ichso posted 30!

[XLjedi]

i modestly submit my very first tutorial video.
.
.
.
view it and PLEASE offer constructive critisism.

thanks!

http://hosted.filefront.com/GoldenRivet/


:o wow... nice video. I liked it.

You're manually drawing half of a maneuvering board. You plotted the DRM line (direction of relative motion) and since you mention being stationary you are also correct that it equates to the contact TC (true course).

If your sub was moving, you would need to plot a movement vector for your sub and the contact speed and DRM. It's not difficult, I could show you how to do that if you like.

[XLjedi]

If you can't be troubled with making your own whiz wheel (I have made three, and the US ISWAS style is my favourite), the good news is that I am working on an electronic version of the KM whiz wheel that would appear in game. It's at a beta level now, it functions but not really well enough. However I am interested in having a playtester that could give me some constructive advice for it.

Will it be analog or digital? I was planning on inclucing an analog one in MoBo v1.1 myself... I'd be happy to take a look at whatever you've got.

[joegrundman]

It's analog. it looks and functions more or less like the authentic one. If you PM me your email address I'll send you my WIP

joe