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

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

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.

One more detail is the size of the maker's mark for that type of hook. Both of these are good badges I believe, so you can compare this with yours. John

Image attached

Well, it was thought. We have been over the ground of which U-boat badge is nicest looking in the eyes of collectors, I was also wondering if we can tell at this point which badges are the least common, regardless of artistic quality. John

I do not believe that yours is a good one. I have attached what the mark should look like from another thread on this forum. Yours is typical of the post-war reproductions. I think I can see a casting line on yours also. John

When you try to estimate the total number of U-boat badges made during the war, it seems to me that this number should be easier to quantify than any other branch of the service. We know there were 40,000 or so men who could have earned the badge, 28,000 killed, 8,000 captured. Since U-boat manning, and therefore badge requirements, was limited to the number of boats in the annual construction plan, badge production could have been fairly accurate. In the case of the Army, I can see where huge numbers of wound badges, other army badges might be made as the war went on since they kept adding men to the army, but not adding men to the submarine branch due to the obvious boat and training restrictions. Could we estimate that 50,000 badges were made, 40,000 awarded, 20,000 survived the war in total, worn and unworn? I do not know, just thinking about it a bit. If 20,000 survived the war, how many exist today, 12,000-15,000 maybe. Myabe less. Again, I am just trying to see if we can make an accurate guess. This leads to the question maybe best answered by our own observation, what would be the order of scarcity for badges based on what we have seen over the last 10 years, maybe for the top ten. I do not think SB would make that list for example. Thoughts or knowledge about this appreciated. John

Postwar Assmann mark.

Gordon, Not sure what your reference book will indicate, and I am looking forward to buying a copy when it is published, but did you determine that this badge was indeed made by Herman Wernstein or not? John

Thanks Gordon, For some reason I thought the badges were made somewhat like a coin would be made thereby leaving the line. I was arguing with a machinist over the subject and it turns out neither of us knew what we were talking about. Your photo and explanatiion clears it up. John

photo

3rd reverse

Next for 3

Reverse

another one I found

Is there any sure way to tell the difference between the KM badge and the post war badge used by the German Navy.? It seems to me to be exactly the same. Check this one, I do not see the difference between this and the Bundesmarine badges. John

Just a general topic about the techniques of manufacture for the KM badges. It is my understanding that two methods existed, the die-struck and die-cast. It seems to me with die-struck, that there would always be an edge going around the badge that would have to be finished by the manufacturer that would appear as a line when complete. So therefore, all tombak badges would have such a line. With a cast method, I assume a wax or plaster mold was available, and the zinc or other metal poured into the mold and no line would exist. For cast reproductions, perhaps a line would exist since the mold would have to be cut I think to get the original badge out of the mold, then the mold reattached somehow before the new hot metal was poured in. Anyway, I do not know and am looking for better clarification on what I am seeing on both the orginal tombak and zink badges and also the reproduction cast versions.

Hi Michel, nice to hear from you again. Gordon, I admit I cheated when you asked the question and searched the forum and found your previous answer. I was sure it was a Zimmerman when I obtained it some time ago. When I made this post, I thought I knew the answer and was wrong. Anyway, for others, the top arm of the swastika is solid on a Mayer, cutout on a Zimmerman. Mine is solid. Thanks, John

Reverse

Do you think this is a Mayer or Zimmerman badge?