Denmark Strait hits on HMS PoW

Discussions about the history of the ship, technical details, etc.

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paulcadogan
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Re: Denmark Strait hits on HMS PoW

Post by paulcadogan »

Cag wrote: It's trajectory was rising relative to the ship as it passed through (12 feet inside the ship).
I find this very curious. Deflected upwards after passing through the outer hull? Or was the ship heeling to port in a starboard turn?

In the report, the comment was that ship was not rolling, but Brooke notes the ship heeling significantly during the maneuver to avoid Hood.

In turning towards the Germans she would have heeled to port, in coming back to her original course and in turning away she would have heeled to starboard.
dunmunro wrote:A 1700lb shell that punches through multiple bulkheads will be felt as it involves a considerable transfer of energy. It seems very likely that this was the hit felt in the transmitting station and recorded on the AFCT plot. I suspect that the bridge would resonate in sympathy with the hull after an UW hit.
This makes sense. After all, according to the Baron, Bismarck's crew felt the impact of PoW's hull hits too.
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Re: Denmark Strait hits on HMS PoW

Post by Byron Angel »

IIRC, Japanese Tosa experiments regarding underwater projectile travel revealed that the path of conventionally shaped pointed projectiles would gradually curve back toward the surface. This would have been consistent with the observed behavior of heavy delay-fuzed artillery projectiles striking soft ground in WW1. Provided that the shell were to strike sufficiently short, it is therefore not completely unimaginable to observe an upward projectile path within a target ship.

B
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Alberto Virtuani
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Re: Denmark Strait hits on HMS PoW

Post by Alberto Virtuani »

Dunmunro wrote: "A 1700lb shell that punches through multiple bulkheads will be felt as it involves a considerable transfer of energy. It seems very likely that this was the hit felt in the transmitting station and recorded on the AFCT plot. I suspect that the bridge would resonate in sympathy with the hull after an UW hit."

Paul Cadogan wrote: "This makes sense. After all, according to the Baron, Bismarck's crew felt the impact of PoW's hull hits too".
Hi Duncan, hi Paul,
the Baron was absolutely unable to feel any hit on the Bismarck from his position (see his book), despite at least one of the shells did explode in the ship..... Only people down the hull, well inside the ship, were able to feel the PoW shells.
I don't think that anybody in the PoW Compass Platform could be able to feel a shell not exploding and hitting (after being relented by the water) so low in the hull, while PoW own full armament was firing rapidly, covering any other sound/feeling. It is however possible that such a hit could affect the transmitting station.
In my poor view the only hit that could be felt in CP before the No.1 is the No.2 bouncing on the roof of the chart room behind the CP.....


Please also keep in mind that there is no time for Bismarck to have switched fire after sinking Hood, to have hit aft the PoW, and to have hit the CP with two different semi-salvo. PoW started her turn away to port at 6:01:30 under full rudder (according to her turning performances and all PoW maps), thus the order was given at around 6:01, with the CP hit landing at 6:00:50 (see the PG film showing PoW salvo 16), thus fired from BS at 6:00:30..... IMHO, it's almost impossible to insert another 15" salvo before the CP one, if we don't accept the fact that the hit corresponding to salvo 16 was the UW one, and that Capt.Leach ordered the disengagement even before the hit in CP, just after Hood explosion, as per his report comments.
"......Prior to the disaster to the Hood, I felt confident that together we could deal adequately with the Bismarck and her consort. The sinking of the Hood obviously changed the immediate situation and there were three further considerations......In all the circumstances I did not consider it sound tactics to continue single-handed the engagement..... Accordingly I turned away and broke off the action......
Bye, Alberto
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Re: Denmark Strait hits on HMS PoW

Post by Cag »

Hi All

Thank you Mr Jurens Mr Saxon and Mr Angel for your expert help it's much appreciated. In my humble opinion I fully agree the shell must have done something prior to hitting and therefore we may only be able to say it came from a forward direction relative to the ship and nothing else.

Hello Paul I too was confused ( easily done for me these days) I think the double bottom of PoW came up the ships side a little way at this point so although near the bilge keel there would still be a outer and inner plated area. There was the oil fuel tank in the SPS and a diesel tank in the ships bottom both damaged, there are quite a few IWM interviews where crew say they knew something had hit because PoW was leaking oil and in the report station 184 is mentioned as being an area of concern prior to the dry dock being fully emptied.

As Duncan and Paul say the diesel dynamo room felt a blow as did the TS which they related to salvo 12 but as to whether it was this hit, it is difficult to say but we know the underwater hit came from a forward direction.

Hi Alberto I do see your point but we have Mr Hunter-Terry giving the funnel hit at 06.01 whilst watching Hoods bows pass by which means the hits may have occurred before this time not at 06.02 as Leach says? Plus we have the continuation of PoW's course after Hoods loss this to enable her to fire at least five more full salvos. I'm not sure why if Leach decided to disengage as Hood exploded, he then conned her round Hood and allowed her to steam on to get in five more salvos before turning away? But of course I agree intention and execution are two different things. A problem I also have is the 5.25 fire on the map and the hit that knocked them out as there is a large gap between the two? Perhaps the the Rowell/GAR map is wrong too?

We do have the GAR which tells us that just after salvo 13 or 14 I think Y turret had only 2 functioning guns and it was at salvo 20 IIRC Y turret jammed whilst the ship was still in action ie before salvo 21 so whenever the decision was finally taken it does seem to have been the correct one.

Thank you all for your contributions
Best wishes
Cag.
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Alberto Virtuani
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Re: Denmark Strait hits on HMS PoW

Post by Alberto Virtuani »

@Mr.Cag,
I do agree with your considerations and that's why I still think that the "salvo 16" splashes visible in the film are related with the CP hit and not with the UW hit, but I was trying to follow Dunmunro theory to explain the "heavy hit aft" and the transmitting station concussion....
BTW, at salvo 12, Bismarck was still firing against Hood , therefore in any case no 15" hit could occur at that battle-time...... :think:

IMHO, the most probable (fast) sequence of the events is the following:
1) Hood explodes at 6:00:10 / 6:00:20 (shell fired at 5:59:50 / 6:00:00;
2) switch fire is immediate and BS fires at 6:00:30 and hits PoW in CP at 6:00:50 (just before salvo 16 and few seconds after PG hit the fore directors support) with the ship on stable course 280°, after the slight avoiding maneuver;
3) BS fires other 3 salvos and hits PoW again around 6:01:20 / 6:01:30 (funnel hit) and at 6:01:40 / 6:01:50 (UW hit), while PG hits (No.4) at around 6:02.
4) PoW fires other 2 salvos (17 and 18) while the turn away actually starts at around 6:01:30 and ceases fire in central control is at 6:02.
5) No other heavy hit occur after that time, just the 2 PG hits aft (from behind) at 6:02:30.


Bye, Alberto
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Cag
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Re: Denmark Strait hits on HMS PoW

Post by Cag »

Hi All

Thanks for that Alberto.and a happy new year to you and everyone!

Am i right in thinking that Bismarck fired a sixth salvo at Hood? Plus wouldn't the flight time of Bismarcks shells be over 20 secs even at the lowest ranges?

The thing I was trying to understand was if it was possible because of the tumbling effect of the shell to gauge it's path and narrow down when it hit.

I guess I'll have to keep working on it but thank you all for your continued much needed help and I hope you all have an excellent 2017

Best wishes
Cag.
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Alberto Virtuani
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Re: Denmark Strait hits on HMS PoW

Post by Alberto Virtuani »

@all: Happy New Year !

@Cag:
hi Mr.Cag,
the flight time of Bismarck shells was 24,2 secs @ 16 km, 22,4 @ 15 and 20,7 @ 14. It's technically possible, but not proven AFAIK, that Bismarck could have fired another semi-salvo to Hood after the fatal hit (for sure not a full sixth salvo).
However this would set the count of shots to Hood to 44 (vs 40 as reported by the Baron), it would shorten the time to switch fire to PoW virtually to zero and it would set the total number of shots ordered by Bismarck during the battle to 112 (vs 93 actually fired) with a loss of output of 17%, that seems a bit too high (the "criticized" PoW guns had a loss of output of 25% during the action).

That's why I tend to think that no other shots were fired to Hood after the fifth salvo and that in less than 40 seconds (a remarkable performance anyway) Schneider switched fire to PoW, hitting the PoW CP with his first salvo.


Bye, Alberto
"It takes three years to build a ship; it takes three centuries to build a tradition" (Adm.A.B.Cunningham)

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Re: Denmark Strait hits on HMS PoW

Post by Cag »

Hi All

Thanks Alberto so the CP hit would therefore be at around 06.00:54? In that case what do we believe caused the pointer oscillations and blown fuse in the TS at salvo 12?

According to the GAR salvo 12 was just after 05.59 a full minute prior to Hoods explosion. This could only be from
a hit/very near miss, or an extreme evasive manoeuvre? There was I believe no other evidence of any other hit ie from PG on the hull of PoW in this area? Would an explosion of an 8 inch near miss cause such an obvious extreme reaction?

Also is it not a possibility that the funnel hit/UW hits were from the same salvo?

Unfortunately I think I'll have to add all this to my ever growing list of things to study! (oh dear!) Also Bismarck and Prinz Eugen turned away at 06.04 to avoid torpedoes is that correct?

Best wishes
Cag.
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Alberto Virtuani
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Re: Denmark Strait hits on HMS PoW

Post by Alberto Virtuani »

Hi Mr.Cag,
as you said, a possible explanation for the TS problem could have been a near miss from an 8" shell from PG..... even if I agree that it's a bit difficult to imagine that it could have had such an evident effect.....
Another option is the concussion of PoW own battery fire..... :think:

Bismarck turned away at 6:03, almost one minute before PG, following the latter torpedo alert (as per PG track and PG film and photo examination), that is again something a bit puzzling....


Bye, Alberto
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Re: Denmark Strait hits on HMS PoW

Post by Cag »

Hi All

Thanks Alberto, yes it seems unlikely that a near miss caused it but then again I agree it's unlikely battery fire caused it unless it was a rather heavy salvo or the effect of the previous 11 salvos put together!

The only thing that occurred that I can think of that may cause the TS wobble was the 15 inch hit but we're back to salvo 12 and that would re arrange the sequence of the hits and bring back the loss of Hood to 05.59 or so?

Yes the time of the German turn has got me too, the Leach report says BC appeared to turn away as PoW turned away at the Y turret local control salvos ie after 06.03.

McMullen says BC appeared to start turning away after PoW salvo 14? I wonder why BC turned in such a sharp way before PG when it was PG that gave the alarm unless it was something to do with putting off PoW aim?

Thanks again
Best wishes
Cag
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Re: Denmark Strait hits on HMS PoW

Post by Thorsten Wahl »

regarding underwater trajectories I recommend a read from the
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
"UNDERWATER TRAJECTORY OF A SPINNING PROJECTILE"
Fowler's theory of the motion of a spinning projectile is developed from basic formulas of mechanics, with special reference to motion in dense media. A numerical application to Naval 3 inch and 6 inch projectiles, whose forces and moments have been measured by the Bureau of Standards, is made. An impulse coefficient is approximately evaluated so as to make the theoretical results agree reasonably well with the data obtained from Naval experiments in water. (1935)

http://www.dtic.mil/docs/citations/AD0700968
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Re: Denmark Strait hits on HMS PoW

Post by Cag »

Hi All

Thank you very much Mr Wahl for your help it is very much appreciated.

Best wishes
Cag.
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Re: Denmark Strait hits on HMS PoW

Post by Dave Saxton »

Alberto Virtuani wrote: That's why I tend to think that no other shots were fired to Hood after the fifth salvo and that in less than 40 seconds (a remarkable performance anyway) Schneider switched fire to PoW, hitting the PoW CP with his first salvo.
Bismarck will already have the correct range and bearing, and rate, of POW in its computers. Running a solution for the SA could be more or less instantaneous, and the guns are already warmed up.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.
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Alberto Virtuani
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Re: Denmark Strait hits on HMS PoW

Post by Alberto Virtuani »

@Dave Saxton:
Hi Dave,
I agree on the technical possibility.
However, if Bismarck fired the fatal shell at around 5:59:40 (flight time 24 secs) and hit at around 6:00:05, with the explosion evident at around 6:00:10, it is difficult to imagine another semi-salvo before the hit in CP (6:00:48 as the PoW salvo 16 is at 6:00:50) that was fired at 6:00:25..... Up to that point in time, Bismarck had been firing 1 semi-salvo each 30 seconds.....


Bye, Alberto
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Re: Denmark Strait hits on HMS PoW

Post by dunmunro »

Bismarck may have hit PoW UW with a outlier shot from a salvo aimed at Hood.
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