Early editions of this calculator tool were hosted via Google Sheets, but now I maintain it at this website:

https://uboat.yepdidthat.com

Try it out. :)

My four bearings method is also available here on Steam:
https://steamproxy.com/sharedfiles/filedetails/?id=3296045676

Enter values for hours, minutes and seconds to get the number of seconds. This is intended to be used with the speed calculator, if you are tracking contacts at both short and long distances.

This is intended to support players who want to use nautical miles & cables rather than metres & kilometres. Enter values in any field to see their conversions.

NB: From what I can see online, 10 cables doesn't exactly equal 1 nautical mile, but it's so close that it shouldn't hurt too much to just do it that way.

Distance / time = speed. It uses seconds in case your target is close by, and metres because that's what I use (and why I provide a converter). The resulting speed is in knots.

Intended to be used if you want to manually plot intercepts (particularly at long range). But it can also be used to work out what time you will approach a destination, for example if you wish to arrive somewhere during the night. Uses knots and kilometres and provides three results:

• Number of kilometres travelled in 12 hours at the nominated speed.
  
• Hours to travel the nominated distance at the nominated speed.
  
• Days to travel the nominated distance at the nominated speed.

This one comes with its own help text on the page. You will need to provide 4 values:

• Absolute course of the contact, ie where north = 0, east = 90, south = 180, west = 270. Either get close enough to observe it directly, or do something like the four bearing method (see my other guide linked below) to work out the course. If you receive a radio report of a contact's course, you can use that.
  
• Relative bearing of your Uboat to the contact. Essentially the AOB. You can achieve this either by measuring a spotted contact with the bearing tool on the map, or by using the protractor tool to find the angle between the contact's bow and your sub. If you received a radio report, you can try to use that & the reported course to make some predictions.
  
• Speed of the contact in knots. Again either observed or calculated by something like the 4 bearings method, or from information in a radio report.
  
• Uboat speed in knots. You can control this.

Entering all four values will output an intercept angle that you should follow. You can again use the protractor tool to plot it on the map. Start the protractor from the presumed location of the contact, then click on your sub, then move the cursor to find the same angle that the calculator shared. Obviously you need to make sure the angle is in the direction ahead of the contact, not the opposite!

As mentioned on the page itself, if you know the course & speed of your contact(s) you can plot it on the map, then plot your own course via the intercept angle. If you wish to arrive early, go faster than the speed you entered into the calculator.

For example:

We have put our own speed at 10 knots into the calculator and the resulting angle we should travel on is 37.3 degrees ahead of the contact.
If we put our speed at 12 knots, the angle becomes 30.3 degrees instead.

However, if we travel at 12 knots on a 37.3 degree angle, we will arrive on the intersection of both the contact's course and our course early, so we can position nicely for an attack.

Another nice trick here is to use the Travel Distance & Duration Calculator to check at what time you would actually intercept, based on your map work, to ideally arrive in the darkness of night.

Example:

Here I have marked out a position for the contact, with its course and our bearing from the contact.



Using the solution from the calculator, if we approach on an angle of 37.3 degrees and a speed of 10 knots we should intercept at this position. If we move faster, we will get there earlier.

Some short background - thinking about how to perform this function is how this calculator began as a Google Sheet.

For this to work, you need to know what magnification level you are using on the scope. You will also need to have 2 fairly accurate measurements, and you will need to be able to recognise the target in the game's identification book to get its actual length.

It doesn't matter which magnification/zoom level you use, the calculator adjusts for it as long as your measurements are accurate.

• Use the angle markers on the attack periscope (the notches at the bottom) to measure the width of your target. Be as precise as you can.
  
• Work out the distance of the target. You can use the stadimeter tool, or map tools, or the Ship Distance Calculator that I will describe in the next section. You need to be relatively accurate with this for it to work.
  
• Enter the actual length of the target, in metres, from the identification book.

You should now have an accurate AOB value. The calculator provides you with an AOB if the target was heading towards you, and an AOB if the target is heading away from you. It's up to you to determine which one is correct.

Optionally, you can manually measure the speed of the target if you use the HUD stopwatch to time how long it takes to traverse its own length. Typically by completely moving through the periscope crosshair. I included this for situations where the AOB angle is really sharp and not close to 90 degrees.

Example:

I measure the Empire Explorer to be about 20 degrees in visual length at magnification level 6x. It has an actual length of 123.9m. I know the distance is 5920m because I used the Ship Distance Calculator to find it (see the section below to accomplish this).



Plugging this into the calculator gives me an AOB of 60.3 for an approaching target, or 119.7 degrees for one that is moving away from me (like in this case):



I can confirm the AOB is about 118 degrees and the distance is about 6000m by using the bearing tool on the map. Considering the target is quite far away, the margin of error isn't bad at all.

Personally I find this more accurate than the in-game stadimeter tool. Maybe I'm just bad with it.

Firstly you will need to correctly identify the ship type using the in-game identification book. Enter the actual mast height in metres into the calculator.

Then, again using the attack periscope and while noting which magnification level you are using, measure the height of the ship from the waterline to the top of its highest mast by counting the number of milliradians on the left side of the scope.

The calculated result will tell you the distance of the target in metres.

At range and in bad weather it can be difficult to find the correct waterline. Either practice more, get closer, or just wait for better weather.

Example:
This is an Empire Explorer observed with 6x magnification. Its actual mast height = 29.6m.
I measure the height from the waterline to the top mast to be approximately 85 milliradians.



Entering these details into the calculator gives me 5920m:



Using map tools, It is about 6.0km:

This is the fun one.

The page describes it already, but basically this works best if you don't move, work out all the distance, speed and AOB information for a target, flood a torpedo tube, then pause the game.

Then, quickly determine and enter all of the same values for up to 4 additional targets.

The calculator will solve which targets you should shoot at first, and how long you should wait between shots. Just start the stopwatch after you fire at the first target and quickly prepare each subsequent shot to launch after the suggested duration.

It works, I have used it many times. There are some caveats listed on the page, but as long as you don't work with ridiculous or unrealistic firing data it should be reliable.