Kriegsmarine U-Boot navigation instruments

[John R]

Here is a nice and rare navigation instrumnet, but I really don't know for what it was used.

I just got around to looking at this post, sorry it refers to a post 7 months ago. That is not a navigation instrument, I am not 100% positve but I relatively sure that it is a Target Motion Analysis device, and among other things, based on torpedo speed, will give time to impact.

It certainly was not used to find position.

[KM-SPAIN]

John, thanks for your information. I think that it is an instrument to correct the navigation drift of the boats, and for that reason I believe that it is a navigation instrument, although does not mark the position.

[John R]

John, thanks for your information. I think that it is an instrument to correct the navigation drift of the boats, and for that reason I believe that it is a navigation instrument, although does not mark the position.

Interesting, and I will do a little more research with old US diesel submariners here. For a surface ship, no such instrument exists. "Set and drift" is determined by comparing the actual position of a ship with dead reckoning positon or "assumed" position of the ship on the chart.

Once set (bearing) and drift (speed in knots) is known, then this information is applied to the future track and updated with actual positions as they are obtained. It would not be on a device, it would be on a chart. The calculation itself is done on a piece of paper by the navigator as it is a simple one for an experienced officer and the results actually written in pencil on the chart to explain to the Captain and the Officer of the Deck why the ship is steering the course it might be on.

My point, and I admit I am not sure how submarines did it, is that to correct for drift, you have to know the actual positions of a vessel on a track, and if you do know, then you lay your future track on the chart with this in mind.

Also the sectors on your instrument make it look to me to be a device for a weapons calculation, but as I said, I do not know.

I will let you know what I find out if anything. I can certainly find out how a submarine without inertial navigation systems applied drift, but like I said, I can see no reason for it to be much different than a ship on the surface. Since German subs were usually on the surface, and at slow speeds underwater, I would think navigation would be almost identical to a surface ship.

I will also check with my German naval friends of that era and see if they know.

John

[John R]

OK,

I have checked with two submariners, both US, one was a diesel submarine officer, the other a nuclear submarine officer. Both said it was a TMA, a Target Motion Analyzer. I will quote the nuclear officer:

"It's a type of circular slide rule (can't remember the

exact name) used to obtain firing solutions on

targets. We used to wear them on a cord around our

necks when we were tracking a target. I believe the

basic technique was to guess at a target's course,

speed, and range and then check the solution by using

TMA (target motion analysis). We had ancient

computers that did the same thing, but most times you

could do it faster using the circular slide rule.

Haven't seen or heard anything about these in 31

years! I'm sure now days electronic computers are

used almost exclusively for this purpose."

Like I said before, I see no particular way this could have been used to calculate drift of a submarine since you need to have chart positions to do so. I hope this helped. For me, it is far more valuable as a torpedo attack device than a drift calculator.

This is just the opinion of myself and two friends, in the end, you need a U-boat man maybe, but I think he would agree with us.

John

Edited February 28, 2006 by John Robinson

[John R]

OK, I have the German reply to this question:

"The instrument in question is an Entfernungsunterschied/Seitenvorhalt Anzieger for giving the U-boat captain or navigator a tool to calculate an intercept course to a target based upon own ship course and speed on the large bar, enemy bearing on the inner circle (>) and speed on the small bar slider (although it seems to be missing the readout wire or pointer for giving the solution). It was, however very similar to the the Artillerie EU/SV Anzieger which calculated rate of change and produced firing bearing on a read out wire indexed with the grid mark. The one in your photo though was a quick tool for determing intercept course for the boat, although it could be used for calculating a torpedo course setting if the main fire control table was out of action.

Anyway, it is a most interesting piece of equipment and I should imagine quite rare"

I hope this helps for what I think is a very valuable artifact. John

[KM-SPAIN]

Jonh, thanks a lot for your good reaserch. For me is one of the nicer a more rare instruments that I have had.

[guntherprien]

Hello Gordon,

As you asked.

8 x 60 Komandanten glass with code maker CXN, rarer than the BLC.

Best,

Michel

hello michel and km spain

i hope you know my

i see you bot have nice items in your collection

greetz

guntherprien

[guntherprien]

Welcome 'an bord' Gunther, I will see you to Ciney.

bonjour michel

the problem on this forum for my is

my englisch i a disaster my german is mutch better

i have a nice fotoalbum from u boat kapit?n hartman during visiting with his u boat crew in a city not far from m?nchen in 1940?

i will post pitchers

but the problem is my englisch is so bad

i dint know how i must wrigt the words

km spain make always jokes with my desaster englisch

were i must post the fotos ????

greetz

gunther

[guntherprien]

Mark

michel

here is my ub bino

gunther

[guntherprien]

michel

here is my ub bino

gunther

i try and can not post pitchers ?????

gunther

[guntherprien]

i try and can not post pitchers ?????

gunther

i see my pics are to big

gunther

[KM-SPAIN]

Hello Gunther, and welcome on board.

You have a "happy" english, so don't worry about that.

[guntherprien]

Hello Gunther, and welcome on board.

You have a "happy" english, so don't worry about that.

hello km spain

you know i do my best

i try post my pitchers from my album from werner hartman

but can not my pics are to big

and al the work for make them smaller

i dont know how you must do it

i trying make with my camera new on a smaller size

next week i have sommeting new for my collection ? big box navy for check watter stamped deutsche seew?rte and oudsit kopper plate with marine observatorium

also have 4 meter like the u boat thermometer for check the salt in the watter

also a instrument for check the speed from the watter i think is not for the see but river

its not the usial big box like i hat 2 years ago

greetz

g

[guntherprien]

Phosphated stopwatch made by Junghans, but official contract.

hello michel

i have also in my collection the same stopwatch as you with 60 second

and also the rear ohne with 100 sec also phosphated

also not phosphated with eagle in the dial from 60 seconds

so 3 pieces with the eagle ohn the front

regards

gunther

[afx20000]

I think these six watches must be shown here. Regards, Florian