Why was BS behind PG ?

[Alberto Virtuani]

Answer to Herr Nilsson who wrote in "the Plot" thread:

And what says OKM15543?

IMAGE$BAF94DB851D0442.jpg (253.03 KiB) Viewed 5648 times

With my absolute ignorance of German language, I interpreted this as the reason why PG was put in front of BS......

Happy to get a serious translation, of course !

Bye, Alberto

[Herr Nilsson]

Thank you, but there is just mentioned that PG takes over radar monitoring also for the stern sectors.

[Alberto Virtuani]

Oh thanks, can you post the translation of the whole page in English, please ?

Bye, Alberto

[Herr Nilsson]

…is informed, that tailing ships are reporting to Scapa. Group West gets the impression that chief of fleet has proceeded with break-through. At 0005 [combat] unit ceases fogging and speeds up 30 knots. Because of poor visibility caused by blowing snow [ships] went to 27 knots. At 0142 course changed to 220°. At 0228 “Alarm” Tailing ship approaches abaft. Prinz Eugen takes over EMII measuring also for aft sector, because Bismarck’s devices are not properly functioning. Radio monitoring reports demonstrate that the tailing ship detects course, course changes and speeds correctly and rapidly. 0358 alarm ends. At 0407 hydrophone section reports sounds on port in direction 085°. Nothing can be made out on the horizon. Some time later [hydrophone section] reports torpedo noises from direction 195° …

[Alberto Virtuani]

From your previous post in the "Plot" thread and the above translation, it looks like PG passed in front of BS at 20:44 due to the fire of the British cruisers. At 2:28 she just took up the radar surveillance in the aft sectors.

If no other change of position was ordered in this timeframe or after, PG was not in front of BS for taking over the damaged fore radar of the flagship, but to stay protected from the British cruisers in case they were approaching.

Very interesting as it is not what I always read in books and articles.

Many thanks, Marc !

Bye, Alberto

[paulcadogan]

Something is very wrong here! There is a gross inconsistency between German and British accounts which I'm surprised has not been discussed before!

PG's KTB states that at 1922 a cruiser was sighted by Bismarck bearing 340 degrees at which point Bismarck opened fire - firing 5 salvos, signalling JD - permission to fire to PG. PG did not have a target so she did not fire.

From the British side - Suffolk sighted BS & PG at 1922, but slipped back into the mist without being fired at.

From PG's KTB: At 2044 a heavy cruiser is sighted which opens fire on PG. The German ships then switch position with PG going ahead. There is no indication that Bismarck opened fire.

From the British side: At about 2030 Norfolk emerged from the mist to find Bismarck & PG on her port bow six miles away on an almost reciprocal course. Bismarck opens fire on her firing 5 salvos. She retreated into the mist without being hit. There is no indication that Norfolk opened fire - plus PG was astern of Bismarck and Norfolk was ahead of them both. She therefore could not possibly have fired on PG.

What gives??????

Something tells me Brinkmann got the two events totally confused - just like he said PoW opened fire at 0620 when it was in fact Suffolk. Another Brinkmann boo-boo.

[Dave Saxton]

To add further to the confusion, Paul Schmalenbach's notes:

1922: Alarm from BS. Heavy cruiser seen to port ahead. BS fires five salvos

2044: Another alarm, the other cruiser is identified as a county class. On BS the foremast radar through the shock of firing is disabled. Flag signal NW (number change).

Apparently Schmalenbach made a mistake by associating the firing of 5 salvoes at 1922 instead of at 2044. That this is only a typo is evidenced because he correctly associated the shock to the foremast radar at 2044.

[Alberto Virtuani]

@Paul & Marc: one more point: from British side it looks no cruiser ever fired at PG......

BS open fire at Norfolk only at 20:30, not at 20:44 while being still ahead of PG (as per Wake-Walker account).

What was Brinkmann writing ?

Still I have unclear when and why PG was put ahead of BS...... Possibly at 20:44 after the 5 salvos fired at Norfolk.....

Bye, Alberto

[Dave Saxton]

The statements that BS was placed behind PG to clear its arcs of fire against the British cruisers and that it was later having problems monitoring the aft sectors with radar are probably related. Luetjens likely intended to use BS's long range artillery to drive off the cruisers given a good opprotunity.

The Bismarck had two forward radars (on the foretop and on the conning tower) in addition to the aft radar. With the remaining foward radar BS could still monitor ahead. So the numbers change was not so PG could see ahead with its radar in place of BS's forward radar-since BS had two forward radars-, but rather so Bismarck could have unfetterred shooting at the shadowing cruisers. Therefore Brinckmann's rationale for the numbers change as recorded in the KTB is correct.

Bismarck could also use its aft radar for helping firing at the cruisers in place of the primary foretop radar.

But the aft radar's mounting had previously given problems which may have entered into the equation at this point. The AVKS found that the gear drive for the aft rangefinder was so tight that it could actually bind up. Mechanics altered the shim packs, but it loosened up too much and it would oscillate back and forth instead of holding a steady bearing. This made precise bearing reading from the radar impossible and would preclude using it for full radar fire direction vs the shadowing cruisers. If this problem presisted and with the foretop radar out of order, then it would explain PG needing to monitor aft as well. Even if this problem had been resolved since the AVKS testing, PG may still need to monitor the aft sectors; if BS's aft set was being used to continuously track a single target, and with the foretop radar still being out of order.

[Alberto Virtuani]

Thanks Dave, it make sense except Brinkmann confusion about timing and firing from BS and British cruisers.....

However, are you sure the problems were affecting only the foretop radar ? It looks less exposed to gun shockwave than the conning tower one and the Baron in his account is clear that BS was blind forward.....

Also, if the reason why PG was in front were the cruisers and the need to leave BS free to fire at them, why was this position kept after the contact was lost at around 00:30 on May 24 ?

Bye, Alberto

[Dave Saxton]

If it was the forward set and not the foretop set then Bismarck would not be blind forward or aft because the foretop set can see all sectors. However, if Schneider and Lindemann wanted to use the foretop set (assuming it was working) to continuously track the cruisers (possibly one set on each?), and the conning tower set was disabled, then Luetjens would need PG to assume overall monitoring of both the forward and aft sectors. Schmalenbach did specify the "Vormars" set, nonetheless. Maybe I am miss-translating that as foremast instead forward?

There are many questions as to Bismarck's radars in which the answers went down with ship. What radar was knocked out, what was the specific fault, or when or if it was put right can not be known for certain.

Seetakt (after mid 1940) did not demonstrate a weakness to being knocked out by its own ship's gunfire shock. There are only three known events of this happening and they were not the same faults:

1) Scheer against HX84. In this case the radar wasn't knocked out but suspected of being knocked out of calibration. It was re-calbrated right after the action and gave no more trouble.

2)Bismarck in Denmark St. Unkown fault and of unknown duration.

3) Hipper's foretop set at Barents Sea. It was two unrelated faults, a broken vacuum tube base, and a broken cable in the ship's power supply. It took almost 1 hour to fix the faults. The SKL was very critical that it took that long to fix the faults. What is interesting about this is that such faults were expected to diagosed and repaired in a matter of minutes.

Since it was an uncommon occurance, the probability of both forward sets being knocked out is not likely. AFAIK, Tirpitz did not report having its radars knocked out by shock during practice shoots. Was the fault on Bismarck like the other two (Scheer and Hipper), or something completely different?

[Dave Saxton]

Also, if the reason why PG was in front were the cruisers and the need to leave BS free to fire at them, why was this position kept after the contact was lost at around 00:30 on May 24 ?

Bye, Alberto

I don't know of any evidence which suggests that the Germans knew they were not being tracked during that time frame. Indeed the Baron points out that they could not shake their shadowers because the cruisers now obviously had radar.

During previous operations it was clear that the British could not maintain contact, so the Germans would ignore a radar contact rather than do something that might reveal their position to the radarless enemy.

The Bismarck's radar detector would still being detecting enemy radar pulses as well.