[TEC] Telemeter scale in the german optics

[don1reed]

Yes, Irish, they did. Not to hijack the thread, but Camo/deceptive paint jobs also to deceive length overall...especially during WW1. No matter how tall or short a mast, the LOA from a 90˚ perspective works just as well.

edit: viewing a man on deck and allowing for ~2m for his height, one could just as easily compute range.

btw: welcome aboard, badwolf!

[badwolf]

Thankyou don1reed,
A new alias badwolf (aka - The Bad Wolf), but my old computer died, flung it overboard. Couldn't retrieve old data, so as everyone called me badwolf anyway. I took it up.

The reason I was interested in the thread was that I'm changing the GUI to suit my own taste and hopefully improvements. Have had trouble associating U-jagd with the inbuilt periscope measurements. The Watch Officer's range to the calculated distance, weren't the same. Having read these posts I can correct this error now.

[Hitman]

Given: each tic = 10/16˚ = 0.626˚, then,

If the baseline were @ the waterline and the masthead(25m) were @, say the 50/16 mark--

then it seems reasonable that:

25m (x100) = 800m range
(50/16)

Hum, no I think you are unnecessarily dividing by 16. The "/16" serves to indicate that each mark is 0.625 of a degree, not mean that you must add the /16 to your calculations. Therefore the correct formula IMHO to use the stadimeter is as follows:

Mast in metres (x1000) = Distance in metres
Scale heigth reading for the target

25m (x1000) = 500m range
50

and

25m (x1000) = 250m range
100

Thus when a target with a 25 m mast covers 50 units of the scale it is at 200 metres, and when covering 100 units (Which are exactly 6.25 degrees) it is at 250 m i.e. 10 times its heigth.

Probably the scope shipped some slide ruler as equipment to go along with it and simplify the calculations.

You know, if the subs used the height of the mast to get the range to the target ships, why didn't the allies use differing heights and vary them frequently to confuse the range finder? Or did they?

Yes they did, and resulting wrong estimations were not unusual even by experienced commanders. However, given enough time and observations, the commanders estimated well enough other figures to allow for preciser heigth readings. Mast is useful as highest point -which allows measuring from farthest distance with accurancy- but other points are also useful, mainly the main bridge which is easier to estimate by counting numbers of decks and multiplying by average heigth of them.

@Badwolf: wellcome

[badwolf]

Thankyou Hitman
Good to talk to you again.

If that's correct then-

[late war] 100 units (6.25 deg) = [early war] 10 units (6.25 deg)

I thought the divide by 16 was a good argument as it explained why the centre thick lines were positioned that length. 1 to 10 ratio for horizontal line to tip of thick line. Thus giving an instant area prospective for other ranges without measuring. i.e half size = *20 - quarter size = = *40. So good estimation and easy maths gives quick range calculations.

Afterthought
The horizontal marks look like early war. If we could measure that to the vertical to get a relationship (hard due to angle of picture). But it does look more a 10 to 160 ratio rather than 10 to 100.

Additional thought
I do think that the /16 does means divide by 16 if not why not use symbol 10/16 or just 0.625. (probably easier to do calculation in late war)
I can't understand how 100 units*0.625 deg (10/16) = 6.25 deg should equal 62.5 deg

Perhaps running trials is the solution using the officer for conformation.

Anyway thankyou Hitman for helping me out.