PoW's gunnery VS BSM's gunnery

[Alberto Virtuani]

Hello everybody,

ignoring the usual implicit insinuation/provocation in the below sentence (...waiting for the moderator intervention...),

Wadinga wrote: "Perhaps someone with a mathematical bent would like to explain why adding up the shells in all the minutes and then dividing them by the number of minutes is not an arithmetic mean"

It is not, simply because PoW had a turret wooded for almost half the engagement [material redacted by WJJ]

In order to be able to compare PoW and Bismarck RoFs, we need to "normalize" PoW firing before, as done here (viewtopic.php?f=1&t=8491&start=300#p82596). Once done, we get the following:

"Had PoW approached Bismarck with Y turret always bearing, she could have "ordered" 16 shots more (8 salvos * 2guns). With an output loss of 26% she could have fired 16*0,74= almost 12 shells more. Approximating (incorrectly, just not to use McMullen's "table"), PoW would have fired 67 shells in 9 minutes = 7,4 shells per minute..., while Bismarck would have fired 93/14 = 6,6 shells per minute ..."

Of course I don't even try to propose again the more correct calculation using the table[phrase rewritten] as this is a good (and simple) enough approximation.

May I ask if it is clear for everybody now, before [emphasis removed WJJ] we move forward ?

Once got consensus about the calculation and the figures, I will post the last PoW output table, got through the confrontation between McMullen's and Barben's reports, slightly (but interestingly) modifying Mr.Dunmunro table above (http://www.sfu.ca/~dmunro/PoW_salvo_a.jpg), but using almost the same format (thanks to Mr.Dunmunro). E.g. "B" turret lost 3 shots according to Barben, who was in "B" turret during the engagement.
Let's move step by step to avoid to have to get back to the same explanation again and again at any post.


Bye, Alberto

[wadinga]

Fellow Contributors,

If we were looking at the table I requested, we could look at those minutes when PoW allegedly had 9 operational guns bearing and compare her output during those minutes with Bismarck's 8 shells per minute, every minute, as described by the Baron since her open fire. Unfortunately Dunmunro's original does not have the time in minutes for each salvo. Even better would be to derive minutes and seconds from the salvo map, and then see the inordinately-long time it took several of PoW's guns to be ready to fire again.

Then no "normalising" would be necessary, and there could be no question over its validity.

Byron's very percipient point about the centre guns of Y turret highlights the fact that whereas Bismarck's guns kept going minute after minute, firing reliably and consistently, like clockwork, PoW's broke down after only one firing- A1, or two, Y2 and even in the case of Y3 three firings which needed another 2 minutes before firing again. Machines that are unused may be reliable or unreliable. Those that break as soon as you start using them are unreliable. You cannot find out whether they are reliable until you are using them. It is immaterial whether mechanical failure or lack of crew skill make them unreliable, if the system does not deliver it is unreliable. Y turret had been on holiday until half way through and started breaking down as soon as it was used. If it had been used earlier, it would have broken down earlier.

This is why this is an unreliable assumption (one of several presented):

With an output loss of 26% she could have fired 16*0,74= almost 12 shells more. Approximating (incorrectly, just not to use McMullen's "table"), PoW would have fired 67 shells in 9 minutes = 7,4 shells per minu

There is no way of knowing whether a gun is "operative" except to fire it. If it fires it was operative, but may have disabled itself simply by firing like A1 or Y2, effectively permanently in the first case, in the second case who knows?

Since Leach had seen B turret fail to fire on three successive salvoes 16, 17 & 18 when it should, how could he know that the loading snafu was corrected and the guns were ready to tried by the end of the engagement? If they miss three successive salvoes who knows when they will fire again?

Now, let's see...……. A1 and both guns in B and probably 2 guns in Y all failing to fire when they should.

"The guns are OK" it sure doesn't look like it.

All the best

wadinga

[Alberto Virtuani]

Hello everybody,

I see that a forum member has not accepted yet the "normalization" to compare PoW and BS RoF. [material redacted WJJ]

However, we can end the discussion here, if there is a refusal to accept mathematics: if an average effective RoF value has to be calculated, there is no other methodology than:
1) the one I proposed as "simplified" (viewtopic.php?f=1&t=8491&start=300#p82596), giving an effective RoF of around 1.5 (expressed in effective salvos per minute, of course) or
2) the one McMullen calculated exactly in the PoW GAR (http://www.hmshood.org.uk/reference/off ... 09guns.htm), giving 1.41 (actual RoF being 1,895 salvos/minute).
[material redacted WJJ]



[Material redacted WJJ]

"Y turret had been on holiday until half way through and started breaking down as soon as it was used. If it had been used earlier, it would have broken down earlier"

...and it would have (at least partially) recovered earlier (we know Y3 gun recovered in time to fire salvo 21, thus if failing at its 4th shot, it would have failed salvo 7, 9 and 11, firing again salvo 13 onward)...

"Leach had seen B turret fail to fire on three successive salvoes 16, 17 & 18"

Totally unsupported. Source please ? Nowhere is written that B turret missed these salvos.
B turret failed to fire probably much earlier (based on Barber account), once fired the shells available at the time the "ring main" was found to be switched off. Also B turret recovered immediately after the ring was switched on and was in action when the engagement was broken off.
I think however that Mr.Wadinga error comes from me in this case, as in my first drafts of a possible table for PoW output, I wrongly marked these salvos as the failed ones... He should have read further on the discussion I had with Mr.Cag, who explained me how many shells were in the main ring. I have not yet published the corrected table based on this info.

"The guns are OK" it sure doesn't look like it"

[material redacted WJJ]
I would say that, in any case, the judgement of the G.O. of the ship should weight more than the "feelings" of a shaken observator.
Leach was however honest enough NOT to mention any gun actual failure when he took his decision in his report. He just mentioned a "potential" output problem that could have happened and that was in his mind.
Please let's try to stay at facts, not inventing what Leach has never written [material redacted WJJ]
Bye, Alberto

[Bill Jurens]

I have had to make a fairly large number of redactions to some of Mr. Virtuani's recent postings.

I would again caution him to please refrain from editorialization and unnecessary commentary. There is no necessity to insert snide asides and emojis suggesting that other correspondents are in some way deficient in understanding, or attempting to deliberately mislead.

If the need to do substantive redaction and rewriting continues, I will be forced to simply delete comments in their entirety. In that regard, I would suggest he keep backups of postings so that he can resubmit the material, if he feels necessary, rephrased in somewhat more constructive tones, and with potentially inflammatory material removed.

Bill Jurens

[Alberto Virtuani]

Hello everybody,

many thanks to the moderator for all the "suggestions" kindly provided to me.



I would just respectfully add to my mutilated posts that McMullen was the G.O. of PoW and his method for calculating the effective RoF of the ship should not be lightly questioned by anyone not having his experience and skill.

Therefore, the proposal to calculate RoF in a way with very questionable "mathematical bent" (not my words, this time) (viewtopic.php?f=1&t=8491&start=420#p82731) is simply wrong and we have to adopt either my proposed simplified method or McMullen one, both giving a very close result.


Bye, Alberto

[northcape]

Perhaps someone with a mathematical bent would like to explain why adding up the shells in all the minutes and then dividing them by the number of minutes is not an arithmetic mean. It is only by choosing to use different "relevant" periods for the two ships, that one can achieve the kind of statistical sleight of hand being exhibited here.

It is an arithmetic mean, but the arithmetic mean is just a number which in this case does not tell anything about the effectiveness of fire. It is as valid as judging the outside temperature based on the color of the sky. Two largely unrelated things.
In this case, it is not even representative of the ROF if one does not know about pauses in firing. The only thing the arithmetic mean tells in this case , is that somebody has the skills to type in numbers into Excel. That is all.
There is no statistic involved at all - the sample size is way to small to do statistics. You can always calculate a mean, but this does not mean you do a valid statistical analysis.

[wadinga]

Fellow Contributors,

It has been written in response to:

Leach had seen B turret fail to fire on three successive salvoes 16, 17 & 18"

Totally unsupported. Source please ? Nowhere is written that B turret missed these salvos.
B turret failed to fire probably much earlier (based on Barber account), once fired the shells available at the time the "ring main" was found to be switched off. Also B turret recovered immediately after the ring was switched on and was in action when the engagement was broken off.
I think however that Mr.Wadinga error comes from me in this case, as in my first drafts of a possible table for PoW output, I wrongly marked these salvos as the failed ones... He should have read further on the discussion I had with Mr.Cag, who explained me how many shells were in the main ring. I have not yet published the corrected table based on this info.

Since only Mr Virtuani and Cag have seen Mr Barben's account, and Cag was forced to leave the Forum by the hostile attitude displayed towards him by some members, (citation available) we are reliant on the former telling us which salvoes the account describes. Since the only person who might know has not told us, but instead says:

Nowhere is written that B turret missed these salvos.

we might reasonably assume the account does not actually say which salvoes were missed. In any case it is immaterial, unless one is staunchly maintaining that Leach was not justified in estimating the number of failed guns to include B turret at the time of his turn away decision. If the turret failed to fire at all on three earlier successive salvoes that is just as much a factor in Leach's reasonable decision.

I would say that, in any case, the judgement of the G.O. of the ship should weight more than the "feelings" of a shaken observator

However, since the Gunnery Officer was fully concerned with spotting and suggesting rate changes and could not even see his own guns firing, or more seriously failing to fire, whilst the Captain would surely notice how, of the six guns in front of him, one was completely dead, and two others were missing several sequential salvoes. Since these failing guns were the only ones which had actually been used since the beginning of the action, and had accumulated so many breakdowns in only a few salvoes such that only A4 had managed to fire every time it was required to, there was little likelihood Y turret would be any more reliable. And of course it wasn't, in fact suffering gun failures more quickly in use, than the other guns.

It has been said of B turret

and was in action when the engagement was broken off.

Looking at the table which Mr Virtuani now says he will revise, it notes only that B turret had succeeded in reloading its guns by the end of the engagement.

Mr Virtuani previously supplied from Barben's letter:

This means that B turret missed three salvoes, although ready to carry on, with shell in the guns when the action finished

Being "ready to carry on" clearly indicates B turret had no opportunity to actually fire after the failure, clearly indicating salvoes 16,17 and 18 were the ones affected.

With respect, a gun that has not been fired cannot be described as being "in action", as it may fail to fire when required to as all guns in PoW did except A4 and Y4.

All the best

wadinga

[dunmunro]

Hello everybody,

many thanks to the moderator for all the "suggestions" kindly provided to me.



I would just respectfully add to my mutilated posts that McMullen was the G.O. of PoW and his method for calculating the effective RoF of the ship should not be lightly questioned by anyone not having his experience and skill.

Therefore, the proposal to calculate RoF in a way with very questionable "mathematical bent" (not my words, this time) (viewtopic.php?f=1&t=8491&start=420#p82731) is simply wrong and we have to adopt either my proposed simplified method or McMullen one, both giving a very close result.


Bye, Alberto

Unfortunately, GO McMullen did not have access to Bismarck's GAR and so couldn't compile comparable data for Bismarck...and unfortunately neither can we.

[Alberto Virtuani]

Hello everybody,

northcape wrote: "It is an arithmetic mean, but the arithmetic mean is just a number which in this case does not tell anything about the effectiveness of fire"

Correct. Means values are what we are trying to calculate (despite a huge resistance). All the other parameters (including effectiveness of fire, etc), are listed here (viewtopic.php?f=1&t=8491&start=315#p82614) and can be discuss each of them one by one, if needed, but only once we get consensus at least about the average RoF values...

Wadinga wrote: "the account does not actually say which salvoes were missed... a gun that has not been fired cannot be described as being "in action"...the Captain would surely notice how, of the six guns in front of him, one was completely dead, and two others were missing several sequential salvoes"

The available posted parts of Barben report + McMullen GAR give all relevant information to evaluate with a good degree of probability (I would not say 100% reliability) when B turret failed to fire, quite before salvo 16, as suggested to Mr.Cag after his description of the main shell ring. We can re-open this discussion once agreed on means values, however.

Of course, a gun loaded and ready to fire has to be considered in action at the end of the engagement, but this is probably not the case of B turret.

As the compass platform hit happened at around 06:00:50, the order to the helmsman given at 06:01:01-06:01:10 and the actual PoW turn actually stared at 06:01:30 (please, present any alternative timing matching what we see in PoW charts), we know that the "shaken" Leach could not see ANY salvo after salvo 15 (or at least he could not have based a rational decision based on what was happening outside the Bridge).
Salvo 16 happened very few seconds after the compass platform hit (see images from the film, sorry for my limited editing skill, as the last image has not the same contrast/definition of the previous ones, anybody can check at minute 6:46-6:50 of the PG film https://www.youtube.com/watch?v=pPmkOtSveXY):

PoW_compass_hit_salvo 16.jpg (37.66 KiB) Viewed 854 times

Dunmunro wrote: "GO McMullen did not have access to Bismarck's GAR and so couldn't compile comparable data for Bismarck...and unfortunately neither can we."

...but very "fortunately" we have the precise number of shells fired, thus we can simulate any number of ordered shots / semi-salvo and get to the same identical conclusions: PoW RoF was in any case comparable to Bismarck's (viewtopic.php?f=1&t=8491&start=315#p82614). Sorry for that.


Bye, Alberto

[paul.mercer]

Gentlemen,
Another question for you I'm afraid!
There have been several points made about PoW's (and Hood's) guns being 'wooded' due to the angle of approach, just out of interest, had Rodney (or Nelson) with their three forward firing turret,s been there instead of PoW would her guns have been 'wooded' as well? I seem to remember that the 'Nelsons' could bring their rear turret around so far that the blast from the guns could shatter the bridge windows and almost deafen those inside.
I still have somewhere a very, very old 'Boys Book of the Navy' which had pictures of the ships and answering a question of the unconventional armament the answer was something like 'a rear turret is not needed as battleships are meant to fight and not run away', very stiff upper lip stuff of course and written around the time that the RN was the biggest navy in the world, but interesting nevertheless.

[Alberto Virtuani]

Hi Paul,
I'm afraid this is a bit off topic here. I'm travelling right now and without "confirmed" Arcs for Nelson's rear turret. As far as I remember, the rear turret could fire up to 25° from the bow and 30° from the stern.

Due to the fact that PoW bearing to enemy varied from 335° to 328°, I would say her rear turret was exactly "at the limit" when the ship was on 300° course and well free to fire when on 280°.

However a slow "Nelson" (23 knots max) could have never sailed the whole night following Hood at speeds varying from 25 to 28 knots. Therefore this scenario is not much realistic.


Bye, Alberto

[pgollin]

.

IF we want a proper log for POW's fire, then we need to ensure it gives as much information as possible, I would SUGGEST the following column headings ;

A: Salvo number

B: Time

C: Guns bearing on target

D: Guns available to fire

E: Guns ordered to fire

F: Guns fired

G: Reasons for casualties

H: Reasons for any gun able to fire not being ordered to fire.

Not all information will be available, but by putting as much down in one place their MIGHT be less arguments.

.

[wadinga]

Fellow Contributors,

I think something significant has occurred:

we know that the "shaken" Leach could not see ANY salvo after salvo 15 (or at least he could not have based a rational decision based on what was happening outside the Bridge).

Admission that given his circumstances, being rendered temporarily unconscious, possibly herniated by the shockwave of a supersonic projectile passing close to his body, splattered with body parts and metal and wood debris, "he could not have based a rational decision" because he was at least "shaken" is considerable progress.

Once again the entirely speculative timing of the PG film is trotted out as if it could be used to precisely delineate Leach's decision time to 11 seconds, or is it 21? Even Rowell does not guarantee the salvo chart timings to better than two minutes and PG's KTB says Hood blew up at 06:01:20. Speaking of speculation we have:

Salvo 16 happened very few seconds after the compass platform hit

There is no actual evidence of this.

It has been said:

We can re-open this discussion once agreed on means values, however.

This discussion is about PoW's gunnery and the clear evidence that B turret failed to fire on the last 3 salvoes under director control is relevant. That the centre guns of Y turret failed to fire on the last five director controlled salvoes is relevant. Esoteric arguments about the suitability of the arithmetic mean applied to a highly skewed distribution with a high standard deviation and when one side of the comparison is made up of assumed figures instead of real ones is what is irrelevant.

All the best

wadinga

[Alberto Virtuani]

Hello, everybody,

Wadinga wrote: "the clear evidence that B turret failed to fire on the last 3 salvoes under director control is relevant"

Which evidence, please ? Has Mr.Wadinga presented his proposed salvo table for PoW ? I have possibly missed it...

The fact the guns were both loaded and ready to fire at the end of the engagement doesn't mean automatically they did not fire at salvos 16 to 18, anyway salvos not witnessed by Leach (viewtopic.php?f=1&t=8491&start=420#p82741), therefore not relevant in his decision to withdraw. It would have been very strange that with 50% of his main armament not firing the last salvos, McMullen could send the "unconventional" message that "everything was ok" with guns to his (by then "shaken") Captain...

Wadinga wrote: "the entirely speculative timing of the PG film is trotted out as if it could be used to precisely delineate Leach's decision time to 11 seconds..."

Incorrect, the hit in compass is not determined by the PG film. The PoW turn away is clearly depicted on all her charts (including the salvo plot) and the fact that the ship started its turn at 06:01:30 is proven by the director and fore turrets being obscured/wooded after 6:02:20, when salvo 19 could have been fired).
Based on these precise evidences, it's easy to evaluate that the order for the hard turn to port was given to the helmsman at 6:01:00 or max 10 seconds after (20-30 seconds being the time needed to PoW to react to her rudder). Therefore the hit in compass platform happened around 06:00:50, and we are lucky enough to see in PG film this "crucial" salvo (from BS) landing around PoW and, immediately after, salvo 16 fired (viewtopic.php?f=1&t=8491&start=420#p82741), confirming (not determining) this timing.

Any alternative timing/explanation ? Please present it.



If not, can everybody now please acknowledge the average RoF values, as calculated here (viewtopic.php?f=1&t=8491&start=315#p82614 , point 1), 2), 3) and 4)) without further discussions, relevant or irrelevant they may be (in specific forum members' opinion, of course) ?
Thanks in advance for making this discussion (at least slowly) progressing.


Bye, Alberto

[Alberto Virtuani]

Hello everybody,

Wadinga wrote: "Admission that given his circumstances, being rendered temporarily unconscious, possibly herniated by the shockwave of a supersonic projectile passing close to his body, splattered with body parts and metal and wood debris, "he could not have based a rational decision" because he was at least "shaken" is considerable progress"

Which considerable progress should we see here if we all agree that Captain Leach was "shaken" ?

The "fairy-tale books" have always accounted that Captain Leach took a cold and wise decision when he disengaged.

According to his biographer, M.B Wills, in "In the highest traditions of the RN" pag.88/89, "He ordered a turn of 160° to port behind a smoke screen. This decision demonstrated Leach's ability to think clearly in the heat of the battle; it was his finest hour").

Now someone should tell me where is any "progress" if we say that, of course, the decision was not a reasoned one, but the reaction of a "shaken" officer (clearly evaluating the circumstances despite his shock or just panicking, I don't want to discuss this aspect here, as it is totally off topic).




I would kindly suggest to provide a direct answer at least to my last question here (viewtopic.php?f=1&t=8491&start=420#p82747), instead:

can everybody now please acknowledge the average RoF values, as calculated here (viewtopic.php?f=1&t=8491&start=315#p82614 , point 1), 2), 3) and 4)) without further discussions, relevant or irrelevant they may be (in specific forum members' opinion, of course) ?

Thanks in advance.


Bye, Alberto