SUBSIM Radio Room Forums - View Single Post - Tachy-tele wristwatch

joegrundman · 01-23-09, 09:15 AM

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?

01-23-09, 09:15 AM	#6
joegrundman Ocean Warrior Join Date: May 2007 Posts: 2,689 Downloads: 34 Uploads: 0	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? __________________ "Enemy submarines are to be called U-Boats. The term submarine is to be reserved for Allied under water vessels. U-Boats are those dastardly villains who sink our ships, while submarines are those gallant and noble craft which sink theirs." Winston Churchill Last edited by joegrundman; 01-23-09 at 09:25 AM.