What does the "Marks" on a Periscope mean ?

[Davinci]

To make the game a little bit harder, I'm playing without the ships icons displayed on the map.
Still trying to understand how someone would determine a ships course, some of it is clear, while other things are still a bit confusing.

Question - what do the markings on the Periscope stand for ?
https://steamcommunity.com/sharedfiles/filedetails/?id=2637657023

[Dewgle]

I am so happy you asked that :)

The vertical markings are called 'milliradians', 'millirads' or 'mrads' and are used to measure the height of the vessel from the waterline to the top of the tallest mast.

If you know how tall a ship is from waterline to the top of it's masts, and you know the magnification level of the device you're looking through, then you can derive the distance you are from the target. I learned this while playing Wolfpack with the same guys who are now developing Crush Depth.

This is the formula you would use and it works with the vanilla periscope as well as Hard's "Hard Scope" mod. This formula was originally used by the Kriesgmarine but I adapted it to work with the incorrectly modeled zoom levels in Uboat.

At 1.5x magnification (second zoom level)

Mast height / milliradians * 50 = distance to target in hectometers

At 6x magnification (third zoom level

Mast height / milliradians * 170 = distance to target in hectometers

(1 hectometer = 100 meters)

The markings at the very bottom of the periscope are also radians I believe and Hard himself provides a PDF with his mod that you can use to derive the target's AOB using those radian markings iirc.

If you're interested, I show some historically accurate methods for plotting a target's course, speed and distance for use on the TDC mod in this vid. How to use the vertical markings and how to determine the target's course using only your periscope.
https://www.twitch.tv/videos/1003657867

[Davinci]

@McDewgle.
Thanks, this should get Me started.

Another Question - using the default compass tool, if a Circle shows a mile radius , is it a mile or more than a mile?

It seems that years ago the tool was incorrect , has that been fixed ?

[Dewgle]

The compass map tool AFIK measures from the center out which means it will only give you the radius. To get the diameter of the compass-circle just multiply by 2.
https://i.imgur.com/3vql4SU.png

[derstosstrupp]

The bottom horizontal scale in the historical periscope was delineated in degrees, and it allowed the viewer to eyeball a spread angle. It also allowed range by target length to be estimated, with the aforementioned chart having rules of thumb to adjust the answer for smaller AOBs.

[DECAFBAD]

The optics in UBOAT give you neither 1.5x nor 6x magnification

The UZOs were 7x50 binoculars (~7° FOV), but in game what you see is closer to 2° FOV, which would be expected from 25x50 binoculars - (25x magnification in game)

Same goes for the periscopes, not very realistic.

[Quiyo]

Originally posted by Davinci:

.......Still trying to understand how someone would determine a ships course, some of it is clear, while other things are still a bit confusing........

To deterninate the course VISUALLY in this game, you must use the course tool.

Also you can use a self-made attack disc or the Solution solver (free on the subsim forum).

download page
https://www.subsim.com/radioroom/downloads.php?do=file&id=5118

if you want information on how to use the "course tool" or the attack disc, I can provide you in this topic

[Dewgle]

Originally posted by DECAFBAD:

The optics in UBOAT give you neither 1.5x nor 6x magnification

The UZOs were 7x50 binoculars (~7° FOV), but in game what you see is closer to 2° FOV, which would be expected from 25x50 binoculars - (25x magnification in game)

Same goes for the periscopes, not very realistic.

Right but the formula shown above will still work for the in-game periscopes

[Davinci]

Thanks “@ All “,

Originally posted by Quiyo:

[
To deterninate the course VISUALLY in this game, you must use the course tool.

So, that course tool can be used not only to calculate the AOB, but also turned to represent the ships angle?

So, this will not be a 100% angle, but a close enough to fire angle ?

To clear that up a bit..,.
Basically , turn the course tool to represent their estimated course.
Then draw out the lines on the map of that course, then re-use the course tool to get and AOB, correct?

[Quiyo]

Originally posted by Davinci:

Thanks “@ All “,
So, that course tool can be used not only to calculate the AOB, but also turned to represent the ships angle?

the "Course tool" is for calculating the course (better heading). It is difficult to calculate the predicted aob with this tool but it can be done.

Originally posted by Davinci:

So, this will not be a 100% angle, but a close enough to fire angle ?

I don't understand what you mean by 100%. Aob is an attitude that may not represent what you want to calculate (the heading of a plane when lands with crosswind).

Originally posted by Davinci:

To clear that up a bit..,.
Basically , turn the course tool to represent their estimated course.
Then draw out the lines on the map of that course, then re-use the course tool to get and AOB, correct?

No, it is only Visual for course, the use is similar to an attack disc. It is difficult to calculate the predicted aob with this tool but it can be done. Attack disk is easier

Physical explanation (kinematics)

https://steamcommunity.com/sharedfiles/filedetails/?id=2473706632

do you want to know how to use it?

[Dewgle]

No.. Please no.. Please GOD no.. The vanilla course tool needs to be burned, not defended or explained.

There might be a language barrier but you cannot use the vanilla course tool to 'visually' determine the course of an enemy ship. I explain this in the very first 10 minutes of the video I linked above but let me summarize.

To use the vanilla course tool you must use the protractor to measure the angle of difference between your course and the target's course. It's easier to explain visually but:

• Use your ruler tool to draw a line of your u-boat's course
  
• Now do the same thing for the target ship, draw out it's course line nice and far
  
• Find the spot where those two course lines intersect and measure the angle with your protractor.
  
• Turn the course tool until it displays the angle you found on the proractor. Using right or left, red or green, depending on which side of the enemy's boat is facing you. Left or right.

That is how to use the vanilla course tool. It is not used to determine the target's course, quite the opposite, you feed the target's (relative) course into it.

To easiest method to determine the target's course, as explained in the video, is to observe the target's superstructures which are built with hard edges and wait until you see a solid 90° edge on the front or back of the wheelhouse.

Then, using the compass navigation mod, convert the relative bearing observed in your periscope to a TRUE bearing and then add or subtract 90° from that true bearing whether the target is sailing to the left or to the right.

Example:

• At relative bearing 40° in your periscope, you observed the target achieve a 90° angle sailing left.
  
• Using your compass navigation mod you converted 40° relative into 350° true
  
• Subtracting 90° from 350° = 260°

So the target is sailing 260° west. Again this is all described in the above video.

[Davinci]

Yes, I watched some of the video.
But, I’m trying to only concentrate on the game without any mods.

We have discussed the course tool thing before , but I have been using it since ( B119 ) , it works.

To Clarify , sinking ships is not the problem that I am facing.

The main problem today is how to determine their exact course without having it displayed on the map.

Without that exact, or close too exact position , it’s confusing how to draw out their course on the map.

That’s why I asked about the compass tool, thanks for clearing that up about the distance times two.

@ Quiyo - Thanks.

[Quiyo]

Originally posted by McDewgle:

No.. Please no.. Please GOD no.. The vanilla course tool needs to be burned, not defended or explained. :stop:

There might be a language barrier but you cannot use the vanilla course tool to 'visually' determine the course of an enemy ship. I explain this in the very first 10 minutes of the video I linked above but let me summarize.

that you have not understood that aob is an attitude used in the Course tool and TDC?

Originally posted by McDewgle:

To use the vanilla course tool you must use the protractor to measure the angle of difference between your course and the target's course. It's easier to explain visually but:

Originally posted by McDewgle:

How to use a visual tool with the map
¿¿¿¿¿¿???????

Originally posted by McDewgle:

That is how to use the vanilla course tool. It is not used to determine the target's course, quite the opposite, you feed the target's (relative) course into it.

Youn don´t know use a Attack disk or Course tools

Originally posted by McDewgle:

To easiest method to determine the target's course, as explained in the video, is to observe the target's superstructures which are built with hard edges and wait until you see a solid 90° edge on the front or back of the wheelhouse.

Easier? Yes, quicker? NO
In a war (I was only in the army for 2 years, but I was in afghanistan), the time is vital!!!

Originally posted by McDewgle:

Then, using the compass navigation mod, convert the relative bearing observed in your periscope to a TRUE bearing and then add or subtract 90° from that true bearing whether the target is sailing to the left or to the right.

Example:

• At relative bearing 40° in your periscope, you observed the target achieve a 90° angle sailing left.
  
• Using your compass navigation mod you converted 40° relative into 350° true
  
• Subtracting 90° from 350° = 260°

So the target is sailing 260° west. Again this is all described in the above video.

So the course tool works bur easier

[Quiyo]

All visual heading tools work the same way, they look for the angle of difference between one's own heading (Reference) and that of the target and THEY DO NOT USE THE MAP

The image is in spanish but with the graphics you can understand it (if you have doubts I can translate it for you).
https://steamcommunity.com/sharedfiles/filedetails/?id=2596796504

The way to do it is the same way used in physics or engineering (something that few see) to calculate the direction from an observer (submarine periscope).
https://steamcommunity.com/sharedfiles/filedetails/?id=2473706632

here's how to do it with three different methods: Course tool (vanilla), lead solver* and attack disk.
https://steamcommunity.com/sharedfiles/filedetails/?id=2596825866

Lead solver and attack disk can be downloaded for FREE in:
https://www.subsim.com/radioroom/downloads.php?do=file&id=5118

[Quiyo]

here is an example with the Course Tool (Vanilla) and the Attack Disk

the target
https://steamcommunity.com/sharedfiles/filedetails/?id=2589086981

With the vanilla course tolos

First the AoB (50°) but "how i see it" (arrow in 130°)
https://steamcommunity.com/sharedfiles/filedetails/?id=2589087252

Now we set the bearing (turn -30° or 330°), arrow in 100°
https://steamcommunity.com/sharedfiles/filedetails/?id=2589087542

we have the angle w (difference between courses in this case with positive sign), click "Set" and we have the target course.

With the attack disk (sorry, only in Spanish)
First the Bearing 330° or -30°
https://steamcommunity.com/sharedfiles/filedetails/?id=2589435988

the second step is the Aob 50º
https://steamcommunity.com/sharedfiles/filedetails/?id=2589436683

At this point we have again the angle w as in the course tool (Vanilla)

And the third step (the last) is to orientate the compass rose
https://steamcommunity.com/sharedfiles/filedetails/?id=2589437802

comparison of the two methods

https://steamcommunity.com/sharedfiles/filedetails/?id=2600221719

[Quiyo]

Another example with positive bearing and aob > 90° (this is the same course as the previous one).

The target
https://steamcommunity.com/sharedfiles/filedetails/?id=2599542369

With the vanilla course tolos

First the AoB (120°) but "how i see it" (arrow in 60°)
https://steamcommunity.com/sharedfiles/filedetails/?id=2599540823

Now we set the bearing (turn 40°), arrow in 100º
https://steamcommunity.com/sharedfiles/filedetails/?id=2599541751

we have the angle w (difference between courses in this case with positive sign), click "Set" and we have the target course.

With the attack disk (sorry, only in Spanish)
First the Bearing 40°

https://steamcommunity.com/sharedfiles/filedetails/?id=2600222518

the second step is the Aob 120°

https://steamcommunity.com/sharedfiles/filedetails/?id=2600223279

At this point we have again the angle w as in the course tool (Vanilla)

And the third step (the last) is to orientate the compass rose

https://steamcommunity.com/sharedfiles/filedetails/?id=2600224167

comparison of the two methods
https://steamcommunity.com/sharedfiles/filedetails/?id=2600224972