SONAR in the ship

[wadinga]

All,
Especially Dave.

This is an excellent technical description of GHG. http://www.cdvandt.org/GHG1996.pdf

Looking again at the "cofferdam" I suspect it is too far aft and more part of the installation process of the ship's belt armour.

Just removing the GHG from PG before she went to Bikini was no minor matter. 120 sub waterline 3cm holes to fill!

All the Best
wadinga

[Dave Saxton]

Just an off topic comment about the Prinz Eugen article:

It's interesting that the USN techs completely dismissed the radar technology out of hand and didn't even bother to look into it. This attitude could be understandable if they were basing their pre-judgement on late war Allied intelligence summaries of German radar capabilities. These reports tend to be riddled with errors and used outdated data in many cases. Report T-11-219 (also posted by Baurer) is a prime example. Top American radar scientists, such as Taylor and Marcum, took a somewhat different view it would appear, because shortly after the war, obvious German (specifically GEMA/Siemens) derived scientific data began to filter into the body of English language scientific literature on radar.

It's amussing that they would place US Army radars (there is an Army SCR-584 antenna in one photograph) on the Prinz instead of USN radars.

HelloMartin, As many of us have found; B&V will not become involved in Bismarck related topics or provide Bismarck related information in most cases. BTW welcome to the little community here.

[Bgile]

It's easy for me to imagine why u-boats wouldn't use listening equipment very much to find convoys. They would have spent most of their time running on the diesels. The noise from the diesels combined with the noise of wake and wave action would have made listening very difficult, and under those circumstances the mark 1 eyeball would probably have been superior.

When I served on US fast attack boats in the early 70's we didn't rely very much on our sonar during the small amount of time we spent on the surface because it was badly degraded then. Of course it was our most important sensor when submerged.

The GHG installed on Flying Fish formed the genesis of the BQR series of passive sonars installed on US submarines post war. Over time I'm sure it got much better than the German WWII version, but the basic principle was the same. When I was in we were using the BQR-7, so presumably there had been 7 major revisions since the original GHG derived one.

[tommy303]

In the Uboot school it was taught that a commander should periodically submerge to 30m or so in order to listen--once every few hours at least.

[Bgile]

In the Uboot school it was taught that a commander should periodically submerge to 30m or so in order to listen--once every few hours at least.

That certainly makes good sense.

[Panzerschiffe]

Apparently some of the panzerschiffe (Admiral Scheer and Lutzow) had either S-Anlage or GHG as well. Can anyone tell me if the Graff Spee was so equipped?

[Dave Saxton]

According to von Kroge the first set of sonar gear did not complete production until mid 1939. Graf Spee could of had it installed if there was an opprotunity just before the war. The question is was there such an opprotunity, and if so did they take advantage of this opprotunity to install such gear?

[wadinga]

Panzerschiffe,

Koop & Schmolke make no mention of either system in their book on the Deutschland class. I have not read of any successful (or unsuccessful) use of GHG in these vessels. There is no sign of the rectangular S Anlage "windows" in the bows in the launch photos. Dave's list above on calibration kits for S-Anlage leaves out the surviving Panzerschiffe.

Lutzow was torpedoed by Spearfish without detecting anything. GHG was of no use apparently during the Barents Sea fight. There is no mention of GHG assisting Scheer's commerce raiding campaign. I have not read of Graf Spee using GHG.

It maybe that the diesels created more hull noise than conventional turbine installation.

If you hear of any successful use of GHG by anything except a u-boat creeping along at depth I would love to hear about it. Except of course, Brinkmann and Schmalenbach's retrospective identification of two fast running turbine ships at Denmark Straits. In fact I am fascinated to hear of actual examples of submarine use including boat number, date, target and detection distance.

Re-reading Bauer's excellent article referenced above it is clear each GHG hydrophone requires a hole c 8cm in diameter through the hull plates. I am amazed we have not yet found a picture somewhere on some vessel in dry dock.

All the best

wadinga

[Dave Saxton]

There is no mention of GHG assisting Scheer's commerce raiding campaign. I have not read of Graf Spee using GHG.

There is refrence by Krancke of using what can only be S-Geraete in navigating shoal waters near the coast of Norway upon returning from Denmark St in March 1941.

Lutzow was torpedoed by Spearfish without detecting anything.

Luetzow had detected the surfaced submarine with Seetakt radar, at a reported 15,000 meters. Unfortunutely for the Germans, Thiele closed range to investigate the radar contact. When the radar contact dissapeared it was obvious that it was probably a submarine that had sinced dived. By then it was too late and Luetzow had unwittenly delivered itself into range of a submarine torpedo attack. The Luetzow had been making flank speed at the time the radar detection of Spearfish was made, so it's unlikely that passive or active sonar would have been in use.

GHG was of no use apparently during the Barents Sea fight.

This fight didn't really lend it self to the use of passive or active sonar. By then radar was well established as the primary electronic means of locating, tracking, and targeting enemy naval forces among the German and Allied Navies.

[Bgile]

I'm not sure why, but I don't think ships normally heard torpedoes in WWII. It seems odd to me. I've heard exactly one, and it was a practice fish dropped by a helicopter in fairly close proximity to the submarine I was on. I was on the sonar at the time, and it was sure loud from my point of view.

[wadinga]

Bgile,

As always your input is very illuminating, although those unfamiliar with your background may not be aware you were listening from a quiet submarine at depth with 60/70s? technology. However based on lots of WWII submarine movies torpedoes could be heard from a quiet submarine at depth using 40s technology.

My particular interest is whether a surface vessel thrashing along at full speed could hear torpedoes or indeed other vessels.

I am sure Dave is right about S-Anlage but what about GHG? I am researching Spearfish v Lutzow now.


All the best

wadinga

[wadinga]

Dave,

The Lutzow v Spearfish radar usage is interesting. Can you give me your source for

Luetzow had detected the surfaced submarine with Seetakt radar, at a reported 15,000 meters. Unfortunutely for the Germans, Thiele closed range to investigate the radar contact. When the radar contact dissapeared it was obvious that it was probably a submarine that had sinced dived.

Cajus Bekker "Hitler's Naval War" describes the incident the same way, radar contact 6 degrees to starboard 15,000m but Koop and Schmolke apparently quoting the KTB put a completely different slant. "01:20 Radar reports object astern at 6 degrees, 1.5km. 01:26 Turned to port at 1.15km. Nothing seen, no further radar contacts, starboard rudder to original bearing to get us through Skagen Narrows as soon as possible. 01:29 Ship still turning. Enormous shock astern. Torpedo track reported acute angle port side. Assume submarine attack."

Ewart Brookes "Prologue to a War" devotes a page to describing Lutzow's routing further offshore to avoid known British submarine operations, and Spearfish on the surface recharging exhausted batteries after a 60 depth charge pounding, spotting a wake in the dark on her beam. Initially Forbes in command thought it was a destroyer and turned away, but then he realised it was a large ship turning away itself, so swung round again for an attack on the surface. When Lutzow back toward him he fired six torpedoes, hitting with one which blew off both props, collapsed the stern and crippled the Panzerschiff. Spearfish was still damaged from the earlier depth charging so Forbes slipped away, still on the surface in case there were escorts.

I have to say that the idea of an unescorted Panzerschiffe deliberately sailing up to contact in the dark from 15,000m away, when British submarines had attacked a nearby convoy sinking a couple of transports and an escort, seems most unlikely. Much more likely seems the rangefinder mounted Seetakt missed Spearfish altogether until Lutzow had passed her before getting contact at almost point blank range true bearing 006 degrees. Lutzow's high speed and course changes meant only one of six hit, and either these were Spearfish's last torpedoes or withdrawal meant the crippled ship survived to fight another day.

The Luetzow had been making flank speed at the time the radar detection of Spearfish was made, so it's unlikely that passive or active sonar would have been in use.

PG's GHG was in use at 28 knots in Denmark Straits whereas Lutzow was only doing 24 kts. Still no evidence of GHG installation or use in Lutzow.

All the best

wadinga

[Dave Saxton]

Hi Sean,

The Seetakt probably didn't miss detecting the submarine. 6 degrees to starboard is almost straight ahead. six minutes elapsed before it lost contact. If it was detected astern why would it be a decreasing range after six minutes with Luetzow banging along initially at 24+ knots? 15,000 meters seems a bit much though. This is why I used the term "a reported 15,000 meters" because I'm not totally convinced that is correct. Perhaps K&S were thinking the same? The Germans normally used hectometers when calling off and recording ranges rather than kilometers, or yards, or miles, and secondary accounts typically convert hectometers to meters or km. And their radar scopes were normally calibrated in hectometers. Most late war radars such as Mk8, Type 273, SG ....and so forth.. could normally detect a trimmed down sub on the surface at a max range of a few thousand yards, and perhaps a persiscope at 1500+ yards. (The Lorenz Hohentwiel could reliably detect just a persiscope at 6,000 meters according to German documents though.) An interesting comparison is the normal detection range of Calias-B to a PT Boat compared to the USN's Mk8 to give a some idea of likely ranges. The USN Mk8Mod2 could detect a PT boat to IIRC 6,000 yards according to USN documents, but the Calias B Seetakt (a larger antenna than Luetzow's 1940 DeTe let me point out) could detect a PT boat to 15,000 meters according to German tests. 15km is not out of the question for this radar to a surfaced submarine, depending on the sea clutter and propagation conditions. Is 1500 meters more plausable? Maybe, depending once again on the conditions, but there's also the minimum range to account for too, which would likely be around 1000-1500 meters actually.

1000-1500 meters is the Approx. min range of a wide variety of radars. When the Germans tested a FuMO26 on Scharnhorst in Nov 1943 the found that the horizontal polorization of that particular antenna "eliminated the short range shadow effect previously observed" with vertically polarized models of Seetakt. This indicates that there was indeed a short range shadow effect or min range with Seetakt models other than the FuMO26. Surely the Luetzow would have traversed the difference between a 1500 meter detection range and the min range in less than six minutes at 24+ knots.

Returned POWs that had been aboard Graf Spee and Scheer reported that the Germans usually had the rangefinder atop the foretop with the strange radio antenna thingy continuously rotating around and around. This indicates they used a continious sweep method when in search mode, and when not being used for gunnery roles. Seetakt used a coarse range display that covered up to 50,000 meters of range, but then they would use the fine range ranging system to zoom in on a examine closely a given radar contact or a particular region of the time base.

If they suspected a sub why would they not utilize GHG after losing radar contact if they had GHG? This may indicate that Lutzow didn't have GHG but it doesn't prove that Luetzow didn't have GHG. At a little over 1000 yards they should be able to see the sub even at night if Forbes didn't dive- and if that reported range is correct as well. Prager will have the most correct account and he relies on mainly, or directly qoutes, primary documents. I will double check on these questions as soon as get the chance.

[wadinga]

Dave and all,

According to K & S Lutzow was sailing on 130 degrees for home when she first detected a radar contact on 006 astern at 01:20. I read this as true bearing 006 nearly due north ie way back on her port quarter. Just as Suffolk could not continually oscillate her entire DCT to give her Type 284 the scanning capability we take for granted and needed to give the system a rest from time to time, I imagine Lutzow's rangefinder mount may have done the same. Or stopped and concentrated on certain sectors more often than others. Typical slewing rates are about 1-2 seconds per degree so it is not a very efficient way to scan. Hence the development of - the scanner. I had an argument once with somebody about slip rings on DCTs, and most of the evidence I could find was for hard wiring looms, so no continuous round and round motion- more like an Owl's Head. I am sure you know far more about waveguides than me.

The range of 1.5km could be correct, as you say somebody has got their hectometers in a twist, either your sources or mine. In the K & S and Brookes scenario the range then increases after this first contact as Lutzow sweeps past, and Spearfish swings round to fire a salvo at her from astern, the torps gradually catching up at about 10-15 knots relative to make a hit up the chuff at 01:29, nine minutes after first contact.

Poor Spearfish was sunk a few months later with all hands but one, so there may not be too many detailed descriptions other than the above from the British POV.

Working together, we will tease out the truth about these mysterious systems.

All the best

wadinga

[Herr Nilsson]

No time to translate. Sorry.

This is from an official damage report:

Lützow.jpg (50.61 KiB) Viewed 539 times