Estimating target speed

[ninja turtle]

Hi guys

I've been using the 3'15 method with success but I've also seen tutorials on youtube and read that you can use 3'30. Does anyone know which method might be the most accurate? I'm just curious why there are two measurements.

Thanks and good hunting

[reaper7]

One is for Metric, the other is for Imperial.

[ninja turtle]

Originally Posted by reaper7

One is for Metric, the other is for Imperial.

Aha!! Thanks Reaper for the quick reply. That makes perfect sense

[ninja turtle]

One more question, though. Which one is used with which?

I sound quite dense

[Shado]

Hi there, I believe that the Germans used the 3' 15", and the Americans used the 3' 30". The Germans I am sure used the metric numbers and Americans the imperial.

[Sailor Steve]

Americans used 3:00 precisely. 3:15 is adjusted for metric. I don't know where 3:30 comes from, as this is the first time I've ever seen it mentioned anywhere.

[MantiBrutalis]

As 100 yards is something like 91,5 meters, 3:00 would quite precisely correspond to 100 yards, while 3:15 is for 100 meters...

3:30 is something around 110 meters per 1 knot. I don't which metric would that be...

Edit - Anyway 3:15 works for me, managing those extra-precise shots at desired ship compartment.

[Pisces]

Don't know how they'd come up with 3m30sec either.

[Gustav Schiebert]

Originally Posted by Shado

Hi there, I believe that the Germans used the 3' 15", and the Americans used the 3' 30". The Germans I am sure used the metric numbers and Americans the imperial.

So were these methods used operationally? How did they do that without 'map updates' in real life - I've never used that method because I play without updates on, I always thought 3' 15" was a game method only.

If they plotted it, surely that's not as accurate as the U-jagd or the periscope scratchmark method on OLC GUI?

[ninja turtle]

Hi guys

Thanks for all the help with my query. Here's a link to the tutorial I watched the other day:



I'm sure I've read or seen others with this 3'30

[ninja turtle]

Originally Posted by Gustav Schiebert

So were these methods used operationally? How did they do that without 'map updates' in real life - I've never used that method because I play without updates on, I always thought 3' 15" was a game method only.

If they plotted it, surely that's not as accurate as the U-jagd or the periscope scratchmark method on OLC GUI?

Hi Gustav

To be fair at the moment I am using 'updates' as an option in my career, but will try and use the 'plotting method' mod when I'm confident enough. I'm sure this timing method can still be used but maybe takes longer to find the target direction and range estimates for that final speed. There's also the method of placing periscope on the bow, and starting the chronometer and stopping it once the stern has passed. I'm still learning how to play this fantastic subsim.

[Gustav Schiebert]

Originally Posted by ninja turtle

Hi Gustav

To be fair at the moment I am using 'updates' as an option in my career, but will try and use the 'plotting method' mod when I'm confident enough. I'm sure this timing method can still be used but maybe takes longer to find the target direction and range estimates for that final speed. There's also the method of placing periscope on the bow, and starting the chronometer and stopping it once the stern has passed. I'm still learning how to play this fantastic subsim.

Hey ninja - yeah after a while using map updates I went over to the stopwatch method. I use a real stopwatch and a printout of the U-jagd, so I don't have to fiddle with drag-and-drop stopwatches on the screen or anything like that, I can just take one measurement independent of the computer then input it directly into the TDC.

I sometimes even, when in a desperate fast-paced convoy attack, just whack in 5kts for merchant ships and fire. At short ranges you still hit even if they're actually going much faster.

I suppose you use the plotting method on the approach, when you have the time, and that gives you a standard speed for the convoy which you can use throughout the attack?

I read once about an allied tactic whereby on every leg of a zigzag they would also change speed. This would also confuse an onlooker, since they would probably assume a constant speed.

Huzzahs for SH!

[MantiBrutalis]

It is very possible to use the 3:15 rule without map updates. You just need its bearing from you (rather easy) and a confident skill in measuring distance.

If you take those two values 3:15 apart from each other, you have two positions on the map, so you have both AOB and speed right under your hands. These things are far easier done if you're not moving, but still possible to count in your speed and heading.

Things get a little awkward if:
1) You don't have enough time. Doing the measurement at least twice means you will be watching your target for 6 and a half minute.
2) The target is far away. The range estimate miserably fails for me from 3km upward. (see the problem between 1) and 2) ?)
3) You are moving. It gets very hard to account for your own movements. But do you have the time to watch the target for 6 minutes when you should be getting at some estimated firing position?


Personally, I totally fail at measuring distances and estimating AOB. When I try to play without map updates, I frequently fail to get to proper firing position, making the shot even harder. Also I tend to force ships aground or even ram them when leaving the base...

[GoldenRivet]

Ninja Turtle...

here is a simple and straight forward formula i have been using all these years.

1. Come to a complete stop as close to zero speed as possible...

2. While watching the ship through the periscope or UZO, Place the vertical cross hair slightly ahead of the ship. Start the stopwatch when the ships bow touches the periscope's vertical cross hair.

3. Stop the stopwatch when the ships stern crosses the periscope's vertical cross hair. (make sure not to move the scope or UZO at all)

4. make a note of this "Traverse Time" it will usually be something like 30 or 45 seconds or could be more or less.

5. Check the length of ship as recorded in the recognition manual.

Length of ship, divided by "traverse time" multiplied times 1.94 = target speed in knots

take more than one measurement if you can but this is deadly accurate

Example: Ship is 180 meters long, traverse time was 32 seconds

180 / 32 x 1.94 = 10.9 knots

in this case set 11 knots in the TDC and sink her!

[ninja turtle]

Originally Posted by GoldenRivet

Ninja Turtle...

here is a simple and straight forward formula i have been using all these years.

1. Come to a complete stop as close to zero speed as possible...

2. While watching the ship through the periscope or UZO, Place the vertical cross hair slightly ahead of the ship. Start the stopwatch when the ships bow touches the periscope's vertical cross hair.

3. Stop the stopwatch when the ships stern crosses the periscope's vertical cross hair. (make sure not to move the scope or UZO at all)

4. make a note of this "Traverse Time" it will usually be something like 30 or 45 seconds or could be more or less.

5. Check the length of ship as recorded in the recognition manual.

Length of ship, divided by "traverse time" multiplied times 1.94 = target speed in knots

take more than one measurement if you can but this is deadly accurate

Example: Ship is 180 meters long, traverse time was 32 seconds

180 / 32 x 1.94 = 10.9 knots

in this case set 11 knots in the TDC and sink her!

Thanks very much for the technique, GoldenRivet. I will try this method as soon as.