There is multiple ways to determine a targets speed. some methods allows you to get more data than just only the speed. Some methods allows for better accuracy in the results than others. This guide will include the the most common methods of determine the speed for use in a target solution or to shadow the convoy with their speed. The accuracy of the results, will differ depending on your data collection accuracy or chosen method.

This guide will make reference to "AOB" Angle on Bow. If you do not know what it means then please check out this other guide explaining it.
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2553649456
The guide will also assume you know how to identify a ship so the guide will also reference this guide: https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2871279241

The most common and accurate method of determine the speed of a target is by measuring how long time it takes to travel a known distance. This is done by using following formula:

D = Distance Traveled (In Meters) (m)
T = Distance Travel Time (In Seconds) (s)
V = Velocity (In Meters/Second) (m/s)
S = Speed (In Knots) (Kts)

Formula for: Speed in Meters/Second (m/s)

Formula for: Speed in Knots (Kts)
Note: The 1.944 is the rounded constant you need to multiply the velocity (m/s) with to convert it to Knots (Kts). If you need to simplify the constant for easier headmath you can use 2.0 instead of 1.944

When you are are a complete halt (0 Kts) and you can see the targets Bow edge & Stern Edge This is easiest to see at AOB 90°, however you can do this at any AOB. When you are more on it's side you can easier see the ships beginning and end edges there by be able to easier measure the time it will take for a ship to "travel it's own length" in distance. This method of measuring speed can be referred to as the "Fixed-Wire Method".

Requirements:

• Your speed is 0 Kts (The closer to 0 Kts, the better result.)
  
• Know the length of the target (Have identified the target Click for guide)

To begin measuring you have to use your AP, OP or UZO vertical crosshair line. Position your crosshair line just in front of the ship you want to measure its speed and when the ship bow/front crosses the line start your timer (using the in-game keys F1-F4)
Ship bow passes the crosshair line. Start the timer

While you are running your timer do not move your optics until the ships Stern/Rear/Aft crosses the crosshair line.

Ship Stern passes the crosshair line. Stop the timer and take note of the time. In this example we can see the time is 51.39s

Now we need to know how long the ship is, which we can do by identifying if with the Ship Recognition Manual and look at the data for ship length.

In this example we can see the length of the ship is 132m

With the ship length known and the time it took for the ship to "travel it's own length" we now have:

1. D = Distance Traveled = Ship travel it's own length = Example ship 132m
   
2. T = Distance Travel Time = Time for ship to travel it's own length = Example ship 51.39s

If we put that into the formula, we get:

You can use the above mentioned technique even when moving at a known speed. It the same formula but you need to take into consideration your own speed and AOB of the target. You need to match the targets course (or reciprocal course, going in their opposite direction) and do your measuring around it's AOB 90°

Requirements:

• Matching Targets Course (or Reciprocal Course) (The closer to the course, the more accurate)
  
• Know your own speed (And if you are traveling against or with the target)
  
• Know the length of the target (Have identified the target Click for guide)

NOTE: You can measure the speed at more angles and AOB's but for simplicity reasons this guide will not go into how to conduct them

These are the following methods depending on course and speed.

Same Course, Faster than target:
Note: You will have to measure from Stern to Bow (Back to Front)!

Same Course, Slower than target:

Reciprocal Course, Any Speed:

If you know a ships course and distance to you, then you can plot it on the map. If you plot two positions that the ship have been at and you know the timestamps the ship were at those positions or you know the time it took for the ship to move from one positions to another, you can then measure the distance on the map from the first position to the second position.

Requirements:

1. Know the Targets Course (The more accurate the better result)
   
2. Know the Targets distance to the submarine at two points in time.
   
3. D = Distance Traveled = Distance between the two plotted points
   
4. T = Distance Travel Time = The time it took for the ship to travel from one plot point to another

Once you know the the targets course and distance to you, plot it on a map by drawing a long line representing its "course line" as can seen by the dashed line in the example:

"Course line" for 119° plotted when crossing the targets AOB 180°, traveling behind the target

Once a "Course line" have been plotted, you can then draw two lines (or more) that intersects with the "Course line" at two points in time. In this example we made our first observation at magnetic Bearing 078° and the second observation around 58.31s later, at magnetic bearing 072°

Two observation at two different bearings, 078° and 072° with a time difference of: 58.31s

The distance between the two points, we can measure with the map tools to be, 290m

We can then use this information to calculate the speed.

You can determine a ships speed by matching it's course and then its speed. This of course requires that you know the ships course. The more accurate you are matching the course the more accurate your speedmatch is going to be.

Requirements:

• Matching Targets Course (The closer to the course, the more accurate)
  
• NOT be at targets AOB 0° or 180°

Once you are on the targets course you should order the speed to "Dead Slow" As it is a good start speed, already starting at 7.2 Kts. Once the submarine have settled on 7.2 Kts you can then with your AP, OP or UZO place your vertical crosshair line on one of the targets masts or kingposts and keep it still.

Keeping it still on the ship when matching the targets course
If you over time see that it drifts ahead of the target ship, you are then too fast.

If you are seeing it drifting behind, you are then too slow.


Depending if you are too slow or too fast you now need to attempt to match the speed of the target. You can do this by increasing/decreasing your engines by 10 RPM at the time. In order to do so, move your EOT between the "Attention" and "Both engines 10 faster/slower" in order to increase or decrease your speed.

You can change your RPM at the "Engine Order Telegraph" (Left image) and you can see your RPM at the diveplane station (Right image)

NOTE: If you can not achieve a perfect speed, you can try to go a little bit faster and then use the dive planes to add a bit of drag to slow you down.

Once the vertical crosshair line is not moving (over time) you have got the speed right.
You can then check what speed you have, to know the target speed, check it at the Navigators Chart


The Navigation Chart allows you to reed the speed in a digital format and it eliminates any potential optical mistakes

NOTE: Do not use the Odometer at the helm station! As characters head is in a position at a angle above, you might mistake the speed as the needle is floating on top of the disc containing all the values. This is caused by the effect called parallax. You can minimize this effect by hopping on the helm station and panning your screen and center over the middle of the odometer but to be complete sure better use the navigational chart

In the games current state (Ver 0.25) you can use the smokes angle coming out of the funnel as a rough indicator of the speed of the target. This method is not the most accurate way of doing it but when you are close enough to a target you can afford being little inaccurate with your data and still hit your targets. For the most accurate result you need to be close to the targets AOB 90° (The closer to 90° the better result.)

Requirements:

• To be close to the targets AOB 90° (The closer to 90° the better result.)

The faster a ship goes the more the smoke's angle going to be. Below you have a few examples that might help train your eyes to estimate the speed.

Many of these methods works for version 0.25 if they will work in future version, well that have to be tested. The smoke might be affected by the windspeed setting and the waves might toss you around too much to be unable to acquire a accurate data enough for determining speed, but most likely these methods will be still useful and used but perhaps for the situations that is suitable for them to work in.

All speeds have been ascertained by making a custom missions where their speed have been specified. You can do this yourself and doublecheck my findings!

The community is small and if you have not yet joined the discord you should. Its a good platform to share knowledge, ask for help from experienced players, find other players to play with, join events or follow up with the development process. Join me there and ask me questions over voice Official Wolfpack Discord[discord.gg]

Other Guides By Fox

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2894764377
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2870513651
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2842875340
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2553649456
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2568475031
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2871279241
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2994179687