PoW's gunnery VS BSM's gunnery

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

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Alberto Virtuani
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Re: PoW's gunnery VS BSM's gunnery

Post by Alberto Virtuani »

Hello everybody,
pgollin wrote: "I think we can ALL take the appropriate meaning from Alberto's refusal to allow the examination of his supposed document."
...as well as we can ALL take the appropriate meaning from "pgollin" refusal/inadequacy to stay on topic....




The following are the data we can get from official documentation (ignored in the official Tovey's report and in almost all books written after, until the gunnery analysis of Adm.Santarini (download/file.php?id=3420), not to "reinforce doubts" about Capt.Leach's (IMHO debatable) decision to disengage) that show how PoW fired, compared to Bismarck.

PoW_BS_gunnery_comparison.jpg
PoW_BS_gunnery_comparison.jpg (117.69 KiB) Viewed 1035 times

This is the topic of the thread (I'm ready to discuss the above numerical and quantifiable facts), not the design/problems inherent in the British 14" gun turrets (at least not here).



Bye, Alberto
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Re: PoW's gunnery VS BSM's gunnery

Post by Bill Jurens »

O.K. Let's restrict ourselves to an examination of the table.

Numbering the columns from 1 through to 12 left to right we have:

Column 1 -- ship name -- of course required. Why is Hood omitted?
Column 2 -- fire duration (the values here have, of course, been questioned by various participants)
Column 3 -- trivial -- merely a re-computation of column 2. Of what practical use is this?
Column 4 -- Number of fired salvos. This might depend upon one's definition of a salvo, and records might be debatable. But see Column10?
Column 5 -- Number of fired shells. This seems reasonably well-documented, though still open to question.
Column 6 -- Ordered shots. I know of no real official references for this, as shots are rarely individually ordered. "Expected" shots??
Column 7 -- Salvos per minute -- merely a derivative of columns 4 and 2.
Column 8 -- E.F.G. salvos per minute -- presumably a derivative of previous columns. Can't reconstruct. Explanation would be useful.
Column 9 -- Output loss %. Presumably a derivative of columns 5 and 6.
Column 10 -- Guns per salvo when not wooded. Presumably just number of guns in main battery / 2. But would not apply to POW.
Column 11 -- Effective shells per minute. I would have guess this to be Column 5/ Column 2, but figures don't work out...
Column 12 -- Weight per minute. Apparently Column 11 times 721 kg. per shell.

The implication of Column 12 seems to be that weight delivered per minute of fire represents a reasonable way to compare.... what? The weight of a 7.62 mm NATO round is around 9 grams. If you gave me a hand-held machine gun, I'm pretty sure I could probably expend 500 rounds per minute -- i.e. 4.5 kilos of ammunition -- downrange without hitting a thing, while a well-trained sniper could probably get off only six or seven shots but do twenty times as much effective damage. Just shooting doesn't count. Hitting does.

Anyhow, it might be productive to have the authors of the table somewhat expand upon these issues, should they choose to do so.

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Re: PoW's gunnery VS BSM's gunnery

Post by wadinga »

Fellow Contributors,

Doubled-Down Post.
The following are the data we can get from official documentation
There is no "official documentation" for Bismarck's firing duration, only assumptions. If this Tedious Table is going to be reproduced over and over simply to fill up space on the pages and push observations based on reality off the current page, it should at least be required to be annotated as being based on assumptions not factual data
.
the only (very conceivable) assumption significantly affecting the effective" figures is the fire action duration of 14 minutes.
And since that is the most significant mathematical operator in the averaging process ie the divisor, the procedure is worthless.

All the best

wadinga
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Re: PoW's gunnery VS BSM's gunnery

Post by Alberto Virtuani »

Hello everybody

@Mr.Jurens: thanks for asking relevant questions.

Please see here the formulas used by McMullen (up to column9 except column3) http://www.hmshood.org.uk/reference/off ... 09guns.htm) and the answers to your questions re.the table:

Column 1 -- Info about Hood are not enough to build a table. The "worse gunner" is the only evident thing that can be said about Hood shooting.
Column 2 -- Duration can be debated, within a tolerance of half minute. Else a credible alternative to what we know is needed.(*)
Column 3 -- Normalization in seconds, just used to make the other calculations easy to be understood here.
Column 4 -- Salvo defined as half armament firing together: for PoW exactly the number of salvos, of course.
Column 5 -- Which "question", please ? 55, 93 and 157 are the reported values from the ships.
Column 6 -- McMullen calls them "total guns able to fired". Guns that should have been fired in the ideal situation of no lost shot due to failures.
Column 7 -- Not exactly. It's = (column4 - 1) / column3 * 60 (please see my explanation here viewtopic.php?f=1&t=8491&start=165#p82455)
Column 8 -- It's = (column7)*(1 - column9/100)) as effective salvos must take into account the output loss due to failures (column9). They represent the equivalent number of "perfect" (no failure) salvos fired by PoW / minute.
Column 9 -- Agree (column9 should be presented before column8 but I have used McMullen's format).
Column 10 -- It does apply to PoW (in case all guns are bearing, as per column description).
Column 11 -- Not exactly. It's column8 * column10. Represents the # of shells PoW could deliver to Bismarck (with all guns bearing) / minute.
Column 12 -- Agree

Regarding hitting or not, as you yourself said, all the other parameters (hit rate, range acquisition, effectiveness of hits, etc.) depends also on luck and/or on tactical decisions that nothing have to do with gunnery efficiency: a ship can straddle 4 times without hitting and another (with identical guns) can straddle only once, but hitting the enemy. Also, a hit can make "superficial damage" only or result in a catastrophic explosion.


Bye, Alberto


(*) The absence of any reasonable alternative makes the procedure correct and "worth".
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Re: PoW's gunnery VS BSM's gunnery

Post by Bill Jurens »

My thanks to Mr. Bonomi for the clarifications as to how the table was derived.

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Re: PoW's gunnery VS BSM's gunnery

Post by Alberto Virtuani »

Hi Mr.Jurens,
you're welcome (my name is Alberto Virtuani).

Bye, Alberto
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Re: PoW's gunnery VS BSM's gunnery

Post by Herr Nilsson »

What about PG‘s salvo succession of 27-28 seconds. I‘m not able to derive it from the table.
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Marc

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Re: PoW's gunnery VS BSM's gunnery

Post by Alberto Virtuani »

Hello everybody,
Herr Nilsson wrote: "What about PG‘s salvo succession of 27-28 seconds"
The table calculate effective average values "normalizing" the firing procedure among all ships: "salvo" in the table means semi-salvo (4 guns for Germans): therefore 3,2 is the average number of "equivalent" 4 guns semi-salvos fired by PG and they are fairly close to a 27-28 seconds interval between the same gun could be fired.

However, we don't know whether PG fired any broadside (or better we know she fired at least 3 Vollsalve as ranging salvos as per Jasper) while we know she fired some (how many?) partial salvos when the fore turrets were not bearing, but the table allows to compare the ships in a way that is independent from how actually they fired their guns.
Total number of salvos for PG in the table is just 184/4 = 46 without any claim she fired her guns exactly 46 times, as we don't know exactly how many actual "salvos" (semi-salvos or broadsides) were fired. However, average values don't care about the firing methodology.


Bye, Alberto
Last edited by Alberto Virtuani on Sun Mar 24, 2019 10:13 am, edited 1 time in total.
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Re: PoW's gunnery VS BSM's gunnery

Post by Herr Nilsson »

Ok, thank you, I understand. But doesn’t this mean that the table pretends an accuracy it doesn‘t achieve?
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Marc

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Re: PoW's gunnery VS BSM's gunnery

Post by Alberto Virtuani »

Hello everybody,

the table presents average effective RoF values (e.g. accounting for lost shots and wooded turrets): these are precise and allow a fair comparison among ships.

No accuracy about the actual RoF (the one Jasper speaks about, that can vary during the engagement and that doesn't take into account the lost shots and the wooded guns) can be derived from it. For this only a salvo plot can give us more info...


Bye, Alberto
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Re: PoW's gunnery VS BSM's gunnery

Post by Herr Nilsson »

Alberto Virtuani wrote: Sun Mar 24, 2019 10:15 am ...

No accuracy about the actual RoF (the one Jasper speaks about, that can vary during the engagement and that doesn't take into account the lost shots and the wooded guns) can be derived from it. For this only a salvo plot can give us more info...


...
You‘re speaking about unintended slowing-down of the RoF. So what about intended?
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Marc

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Re: PoW's gunnery VS BSM's gunnery

Post by Alberto Virtuani »

Hello everybody,

the table doesn't provide any conclusion about any (remotely possible, absolutely unsupported) significant "intended" slowing down of the German RoF.
PoW intentionally accelerated her RoF around and within minute 6:00, while slowed it down (probably unintentionally) during minute 6:01, however, presenting her performance, McMullen used the average values of the table, considering them more than sufficient as the acceleration and the slowing down are not much signiifcant.
Probably Germans had similar variations in their RoF, not much significant (as nobody noticed them).

Does anybody have any evidence that PG or BS intentionally slowed down significantly their RoF at any stage of the battle ?

The table average effective figures (viewtopic.php?f=1&t=8491&p=82574#p82563) are the only ones that can be compared among the ships.

Bye, Alberto
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Re: PoW's gunnery VS BSM's gunnery

Post by Herr Nilsson »

Alberto Virtuani wrote: Sun Mar 24, 2019 11:43 am Does anybody have any evidence that PG or BS intentionally slowed down significantly their RoF at any stage of the battle ?

Bye, Alberto
Alberto Virtuani wrote: Sun Mar 24, 2019 10:15 am For this only a salvo plot can give us more info...


Bye, Alberto
Regards

Marc

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Re: PoW's gunnery VS BSM's gunnery

Post by Alberto Virtuani »

...precisely...

for the time being only effective average values and statistics (viewtopic.php?f=1&t=8491&p=82576#p82563) can be compared.

Bye, Alberto
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Re: PoW's gunnery VS BSM's gunnery

Post by Herr Nilsson »

But that means the table has about the same information value like a top trumps card game.
Regards

Marc

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