Reminder tips on calculating ship speed

[Leoz]

Here are a few reminder tips for people that want to start doing the game with near 100 percent "realism" where you have to determine a target's speed.
Without this one figure, you will never hit what you shoot at.

All you need is a piece of paper and a pen, a calculator, or a note taking function on your smartphone and calculator app.

1. At that first ship-spotted announcement, use the plotting Mark tool and put down that first "Mark 1" on the F5 map. Even if it isn't too accurate, for example, you only have a bearing and have to guess the distance.
2. Write down this first mark as a note with the time. Example. "1105 Mk1" (1105am is the time the Mark 1 plot was put on the map)
3. Try and observe the target course angle on the bow and immediately match its' course, it doesn't have to be perfect. The goal here is to spend a half hour in the game time and get the target's course and speed.
4. Ten minutes later (For this example: 1115, get a course and estimated distance and plot that in your notes: "1115 Mk2".
5. By 1135 you should have 4 Marks on your F5 Map and plotted in your notes. You should now be able to figure out a course and speed of the target.
6. If needed, do an "overhaul". Speed ahead of the target out of sight and get ahead of it where you are able to setup for a daytime periscope attack or surface attack.
7. When the ship appears again, do a few more plots as mentioned above to make sure it agrees with your previous plots.
8. Now you are setting up for the attack, as the ship gets closer, attempt to ID the target. Example: I have not played the Med campaign much and almost launched 4 torpedoes at a friendly convoy.
9. If needed continue the plotting and make sure even if it is bearing only plots that the target is marching down the predicted target course you plotted.
10. If you need to do a "wire method", and a 78 meter long ship covers its own length in 30 seconds, 78 divided by 30 is 2.6, then times 2.6 by 1.85 for 4.81. Round up, the ship is probably going 5 knots.
11. if it is a convoy you are tracking at distance (night or day), try matching its course and speed from the left or right side of the convoy and look through the UZO or binoculars to match speed. Example: after some minutes, a ship you are looking at is neither moving faster or slower than you when you are traveling at 5 knots. There you go.
12. For single ship night surface attacks if visibility is good and you are looking at a target 45 degrees to you...while it is at a 45 degree angle on the bow...and it maintains that 45 degree bearing to you while you are going 8 knots,....it is also going 8 knots. (The drivers training video of how to visually avoid a collision with another car while you are both approaching an intersection).

Other methods:

14. Where you can get directly ahead of a target from distance and see it from zero angle on the bow. Plot that line and you have the ships course. Then go off to the side and plot bearings. If it moved 600 meters down that line in 3.25 seconds, it is going 6 knots.

15. One I am experimenting with in early war night surface attacks where the convoy is all split up from a course change with most ships doing a different course and speed (happens alot in NYGM). Go flank speed, setup your target where it is 90 AOB to you and you are zero angle to that target. Do a quick wire method at speed while looking through the UZO. Inaccurate but may be close enough to launch a spread of 2 torpedoes with 2 or 3 degree spread depending on target size. Also since things happen fast, if it is a 150 meter ship, do the wire method almost at half ships length and calculate for a 75M long ship.



Anyway...hope this helps. Cooking your own firing solutions in the game is both fun and satisfying.

[Pisces]

Originally Posted by Leoz

...
10. If you need to do a "wire method", and a 78 meter long ship covers its own length in 30 seconds, 78 divided by 30 is 2.6, then times 2.6 by 1.85 for 4.81. Round up, the ship is probably going 5 knots.
...

That is using the wrong conversion factor. And rounding up to hide the error.

In order to convert from meters to nautical mile, and from seconds to hours the correct conversion factor is multiply by 3600 (to go from seconds to hours) and then divide by 1852 (to go from meters to nautical miles. In the end that comes down to multiplying by 1.944, or 2 if you want to do it simple and quick. (and still be within 3% close to exact)

Also, there is no reason to round it up to a single digit. Speeds can be any decimal number. If a unit moves at that speed it is likely due to the lazyness of the campaign/mission creator.

14. Where you can get directly ahead of a target from distance and see it from zero angle on the bow. Plot that line and you have the ships course. Then go off to the side and plot bearings. If it moved 600 meters down that line in 3.25 seconds, it is going 6 knots.

3.25 minutes, as in 3 minutes 15 seconds (or 194.4 seconds. Looks familiar? ) , not 3.25 seconds.

Other than that, good approach to tracking a target. Let the plot show it's movement and speed over multiple/tens of minutes. That's where accuracy is shown.

[Leoz]

Thanks Pisces !!!