Tachy-tele wristwatch

[joegrundman]

Hi Guys

i found this thing - in fact i think Hanhart still make them more or less identically, but i seems to be the KM wristwatch for Kaleuns and officers

http://www.historypreservation.com/h...ates/uboot.php

the resolution isn't quite good enough for me to read everything clearly, and it claims to differ from the Fliegerchrono by the same company, although i can't tell the difference from this better resolution image of thisFligerchrono :




anyway i'm thinking of implementing it as an alternative stoppuhr

I have a couple of questions:

does anyone know what the red blob does at the top? is this a rotatable bug?

how does one use the telemeter and tachymeter scale?

thanks in advance

joe

[MauserKar98k]

I think Hanhart watches look awsome, especially the Luftwaffe version:
http://www.historypreservation.com/h...es/Hanhart.php
It's too bad that they are so expensive. I don't have a grand to drop on a watch.

[joegrundman]

thanks for that, it looks like the large picture i posted is in fact the U-boat commander version, not the flieger version, despite the label.

in the link you provided the flieger version clearly does not include Telemeter and tachymeter markings in red

so..now..who can explain to me how to use the telemeter and tachymeter scales

i already answered my other question which is that the red mark at the top is a rotating bug, which presumably is used in conjunction with the telemeter

[joegrundman]

I found that one way to use the telemeter scale is for ranging between the sight of something happening and the sound of it.

so for example you see a torpedo explode and start the timer, then hear it through the air and stop the timer. If it says 6 seconds it's 2km distant.


this is an explanation that i found on the internets, but i can't believe this is what the KM used it for, since (a) the scale is much larger and it was rare that torps ran for more than 3 kilometers, so the entire scale beyond 10 secs would have been unused, and (b) the speed of sound underwater is much faster than through the air.

The markings are in red incidentally to be more effective with battlestations "redlight"

[Hitman]

Ah yes the famous Hanhart watch

I readed some time ago that the scale was meant for timing the torpedo impacts, hence it would act as the current fake red needle displayed in the chrono when a torpedo is shot, showing -according to the set speed- the estimated time of impact.

Here is an interesting link about the use of tachymeters:

http://en.wikipedia.org/wiki/Tacheometer

Given the divisions shown in the external scale (1-20), my bet is that it is probably to allow the commander calculating the speed of his own U-boat, an enemy ships or similar which travels between two marked positions.

The spiral shaped interior scale is clearly meant for longer timings, so probably for the aforementioned torpedo runs.

[joegrundman]

Thanks Hitman

The human U-boat encyclopedia comes to the rescue again!

so by following that link, i've concluded that the telemeter scale and the tachymeter scale are two different things -i'll study the telemeter later

as for the tachymeter, let's suppose we want to use it like we use the U-jagd chrono.

Let's say we have a target of 150m - to get it's speed with the fixed wire method and the UJ chrono couldn't be easier.

With the tachymeter, let's say it takes 30 seconds. On the tachymeter scale it gives a value of 120 (the rings further in are for timings of more than 1 and 2 mins respectively, so is quite useful in that regard)

The value of 120 means the speed in hours is 120 units of the measured length

the measured length was 150 m, so the speed per hour was

120 x 150m = 18000m/hour
=18km/hour
which is about 10 knots

i had a calculator to help me, even for easy one's like this.

Conclusion: it is definitely not as convenient as the UJ chrono, even if it is more versatile

from what i can see: the telemeter really is used for assessing range based on the time elapsed between a visual cue and hearing it though the air - i cannot really imagine what U-boats used it for

One question: when is it so important to have accurately timed torpedo runs anyway?

[Hitman]

Regarding the telemeter:

I think you made the calculation too complicated. The way to make it easier is to use the same units for both input and output, hence you should convert a ship's length to nautical miles (1802 metres).

A 180 metres ship is 0,10 NM

A 90 metres ship is 0,5 NM

A 45 metres ship is 0,25 NM

Following your example they would respectively be travelling at:

120x0,10=12 knots

120x0,5=6 knots

120x0,25=3 knots

But anyway yes, the U-Jagd chrono is still superior

Regarding the tachymeter:

Here is a US Civil War artillery chrono. The inner scale is adjusted to the speed of sound, and it was used to determine distance to enemy artillery by timing the difference between seen the flash and hearing the sound.



See if the scales match :hmm:

You ask for its use, and the answer is simple: Artillery The U-Boats carried a deck gun, remember? Also they could be fired upon by enemies while unable to dive, or they could want to see the distance to a distant battle taking place over the horizon at twilight, etc. But also its use was for metereology, to measure the time between lightning and thunder and determine if a storm is closing or heading away.

Regarding the timed torpedo runs:

The importance of them was:

-To check wether estimations made by the Kaleun or IWO had been correct, overestimated or undersestimated

-To have an idea of when there would be a huge sound in the water that could eventually render enemy hydrophones useless for some minutes

-Similarly, to have an idea of when the enemy escorts would be alerted about the prescence on a submarine

-To listen carefully to the proper bearing for a possible dud or premature detonation (Something BdU emphasized a lot)

I think there will be some more, but right know I can't remember them :hmm:

[Jimbuna]

Thanks for the heads up joe and an excellent explanation H

I was seriously interested until I read to the bottom of the page and saw the price

[joegrundman]

Hi Jimbuna..me too!

Hitman,

excellent, although if you will permit me this small quantum of pedantry, i think you have the names of Telemeter and Tachymeter/Tacheometer swapped around.

The scale from the Civil war artillery chrono does match the Hanhart telemeter scale, after adjusting miles for kilometers. Besides you can calculate it since you can see that 3.4 km matches 10 seconds, and as we all know the speed of sound in air is 343.14m/s at 20 degrees C.

thanks for providing the use - i'd forgotten about deckguns, and also thanks for explaining the use of timed torpedo runs - you know it was never something i'd really thought of as important information, i guess i should.

Finally, does SH4/3 take into account the distance and speed of sound with artillery explosions

[badwolf]

Hi joe
I thought you were paddling about in the pacific.
Anyway I do like the watch.

There was a mod released long ago called Avg.Joes Torpedo & Deck gun Speed-of-Sound Explosions Delay v1.2+.rar
Here's part of the readme

--------------------------------------------------------------------------------
This is a Silent Hunter III (v1.4) sound-delay mod, which changes 5 things:

1. After a torpedo has hit a target, there is an approximate 2-second delay, before any explosion sound(s) will be heard.

2. After a target has been hit with 88mm/105mm deckgun, there is an approximate 1.75 second delay, before any shell-strike sound is heard.

3. The main torpedo explosion .wav file (P11_@ref_torp_great_explosion.wav), has been modified/mixed a bit, to cause a bit more dramatic explosion sound.

***4. The default deckgun .wav file (P09_$Gun_muzzle_flash.wav) has been changed, to make the gun-sound more dramatic.

5. Several explosions are a bit louder than default, and also mixed with other (minor) explosion wave-files, to create (hopefully) more dramatic explosion sounds.
--------------------------------------------------------------------------------

Whether this is incorporated in the supermods I can't say.

[Hitman]

although if you will permit me this small quantum of pedantry, i think you have the names of Telemeter and Tachymeter/Tacheometer swapped around.

Oh no, no pedantry at all, your are right but the definition seems to be a bit confusing, some sites talk about telemeter others about tachymeters

Finally, does SH4/3 take into account the distance and speed of sound with artillery explosions

Sh4 certainly does (Though I can't tell how exact it is), SH3 unfortunately not IIRC the mod that badwolf refers to gives a fixed delay for all sounds, so you would experiment the same delay at 500 or 15000 metres distance. A hardcore limitation, I'm afraid.

[joegrundman]

Hi Badwolf, yes' ive been doing a couple of campaigns with the fleetboats, but the atlantic is where the heart is!

Anyway i'm thinking that for a couple of reasons it's only worth doing this watch for SH4UBM - one, speed of sound is only modelled in sh4, and without that the telemeter scale ahs no value at all, and secondly the SH4UBM chrono includes controllers for the minutes and hour hands of the clock while the SH3 stoppuhr is a stoppuhr only without being a clock too

thanks again Hitman