Calculations errors with the TBT

[Sirkam]

I noticed something.
I played the Battle of Midway mission yesterday and doing the calculations with the TBT, more precisely with the target speed calculation (the clock), it gives me that the target speed was 54 Knots!!. Well, i collect all the data again, and the speed is similar (im played with the metrical option).... What am i doing wrong?

[Rockin Robbins]

First, it does not calculate wrong. Based on the information you provide it, you get a speed estimate. Usually you'll find it's a problem with inaccurate stadimeter use that messes up the numbers.

You're actually lucky in that you could immediately look at the number and say "no way!" Most of the time you just get a plausible wrong number and the way you find out is by watching the torpedoes cruise off to the land of Oz.

Because this method is so wasteful of torpedoes and is not able to be double-checked unless you already know the answer to the question you are asking, I don't recommend using the crew estimate of speed and course unless you just don't have time to do a plot and you can't do another end around to shoot at that target.

In other words, almost never is when you should be using the crew estimate method of determining speed and course.

[Platapus]

Three common causes of screwy speed readings are

Range to target - errors in range can really mess up your speed

Speed of your submarine - Unless your target is +/- 10 degrees from either 000 or 180 relative bearing, your speed calculations will be inaccurate.

Duration between readings - Accuracy in speed calculations improves the longer you observe your target. Also multiple observations help your accuracy. In real life subs tracked targets for many many minutes to get accurate course and speed.

I find using the speed estimation functions in SH4 to be inaccurate.

Personally I prefer using alternate means to get speed estimations

1. 3:15 (3:00) rule works well if you have the contact plot activated

2. Often I will use the direct observation method. This works well as you do not have to know the range to the target to get the speed.

a. Identify the target ship and determine the length in meters

b. Either stop your boat or have your target at 000/180 relative bearing to minimize your speeds influences

c. Put your periscope cross hair just in front of the target ship. Do not move the periscope!

d. When the bow of the target ship touches the cross-hair, start your stopwatch

e. When the stern of the target ship touches the cross-hair, stop your stopwatch

f. Speed (kts) = 1.94 x (length in meters)/(time in seconds)

f1. I "think" the conversion to imperial is Speed (kts) = 0.58 x (length in feet) / (time in seconds) but I am not sure as I do that metric thing all the time

This works for targets at any range and at "most" AoBs

Good luck and good hunting

[Rockin Robbins]

Ewwwwwwwwwww METRIC?????!!!!!!:rotfl:

[Sirkam]

Really useful your method Platapus . I'll starting to practice that method right now.

[Washington]

If you take two good data points and wait enough time between them, your crew will calculate an accurate speed and accurate true course. Let's not be hating on our own hard working crew here I have found the closer the range to target, the better the crew is...I think they all need glasses.

[Sirkam]

Originally Posted by Washington

If you take two good data points and wait enough time between them, your crew will calculate an accurate speed and accurate true course. Let's not be hating on our own hard working crew here I have found the closer the range to target, the better the crew is...I think they all need glasses.

There is a bug that the watch crew miss their eyes, there is the proof :rotfl:.

[Wilcke]

I prefer to use the hydrophone to do the speed estimation whether on a single target or a convoy. Much cleaner you can take your time, then you can decide if it warrants and end run on the surface.

Some of the task forces are just moving to fast for an effective setup.

A good example is in the Single Missions where you are placed 15000 or so yards from a TF that is doing 17 knots....not much to do there aside from trying a "noisy" submerged approach for a hydrophone only attack. Its a fun little mission, try it some time. If you screw up there are 6 tin cans that will just come on over for a visit and offer some advice!

My winning conditions are ...get into torpedo launch parameters....launch six on a spread...and slink away without alerting the tin cans. You can use the periscope if you are feeling lucky.

The Borneo convoy mission is a good training ground as the speed is less than 10 knots and the tin cans are rather dull; unless you get noisy. Try to load as much info into the TDC with the hydrophone then use two scope observations to confirm and refresh the data; 7 seconds per observation please.

With Werners video and this mission you can really hone the blade!

Happy Hunting!

[Washington]

Are you actively pinging the targets then? Doesn't that give away your position? And, with sonar, do the end of the sonar lines represent the range of the target?

[Platapus]

Originally Posted by Sirkam

Really useful your method Platapus . I'll starting to practice that method right now.

Uh it aint my methods. I just stole the good ideas from the other really smart people here

[Ducimus]

Originally Posted by Washington

Are you actively pinging the targets then? Doesn't that give away your position?

My magic 8 ball says, "No way!"

[Rockin Robbins]

Originally Posted by Platapus

Uh it aint my methods. I just stole the good ideas from the other really smart people here

We stole 'em so many times from each other we have no idea whose is whose any more! Some have lost 'em twice. Arrrrr!

But seriously, Platapus is gettin' good! He not only steals 'em but he learns how to use 'em well. That's what being a great submariner is all about.



So when the going gets tough, the tough ....... make a new signature pic!:rotfl:

[Sirkam]

Im too slow doing the equation (in the single missions). Damned mathematics .
But i'm happy after all, i sunk a Kongo Battlecruiser and damaged a Shokaku Fleet Carrier . But the mission still incompleted .

[Rockin Robbins]

The math is real cute but not a productive way to run a submarine. Ditch the math and do it right.

[AFRIKAKORPS]

This may be off topic, but Sirkam I really love your sig:rotfl:!