Battleship Accuracy

While going through old posts and comments, I came across the following comment from ‘Ray D’ [1] about battleship accuracy in a post about battleship and carrier throw weights (see, “Carrierand Battleship Throw Weights”).  He’s responding to a comment that denigrated the accuracy of a battleship’s big guns.  The comment is so interesting that it deserves a post of its own for wider dissemination since not everyone reads all the comments. 
 
Note:  I have no way to verify the accuracy of the reader’s comment but I have no reason to doubt it, either.  I have not seen either of the two referenced reports/sources.  You can assess the validity for yourself.
 
I’ve copied his comment with just a couple of minor changes for grammar and readability.
 
In the comment, the author makes the distinction between precision and accuracy.  Some readers may not be familiar with the distinction so here’s the difference.  Precision is the grouping of several shots from a gun.  The tighter the grouping, the better the precision.  However, a tight grouping (high precision) does not necessarily mean good accuracy.  Accuracy is how close to the intended target the shot is.  Precision is how tight the grouping is regardless of the accuracy.  A series of shots may have very good precision (tight grouping) but very poor accuracy (a tight group that’s way off the target).  Conversely, the accuracy could be good but the precision might be poor.
 
The statement the reader is responding to declared the following about a battleship’s accuracy.
 
"estimated accuracy of 2.7% at max range"
 
The reader’s response was the following:
 

With all respect (and I mean a lot of respect), this comes from probably the most misrepresented report about US Navy WW2 era equipment of all time and the claim ignores the myriad of patently ridiculous assumptions that the report made about the hypothetical target given exactly what naval targets existed at the time.
 
To keep it short, their assumed target was a mythical Iowa-class counterpart that was performing rapid evasive maneuvers and somehow NEVER dropped below its assumed maximum speed of 35.4 knots.
I hope it doesn't need to be explained that this was and is physically impossible!
 
Furthermore, the only Battleships in the world (ever) that were capable of performing such radical evasive maneuvers and maintaining a targeting solution of their own were American; all others would have had to either choose shooting or evading due to their lack of stable verticals; so in real terms the report itself is entirely worthless unless the US Navy was expecting to fight the US Navy.
 
Against a Yamato acting according to Japanese doctrine, ergo attempting to maximize its own gunfire efficiency, the predicted accuracy for the Americans would be closer to 8% at that range, or over three times higher.
 
That aside, in the context of shore bombardment this entire argument is disingenuous and built around an obvious categorical error: at the last I checked, most strategic military targets such as bases, ports, airfields, factories, and governmental offices do not in fact move.
 
So, instead of accuracy assumption against moving targets, it's better to speak of the raw dispersion values of the guns in question.
 
According to live combat data taken from WW2 and Korea, the Iowa-class Battleships during those periods had range errors of only 0.6% of range, or 254yds at their maximum range of 42,345yds, making them the most accurate battleships to ever be built even then. Deflection error was usually negligible in comparison, as range error is always the larger number.
 
Of course, that's just the WW2 figures. Just by the 1980s reactivations advancements made to fire control and propellants saw a ~29% decrease in dispersion, again drawn from live combat data. During firing trials, the USS Iowa produced a range error of 0.3% of range (or ~127yds at maximum).
 
To put this in context, the blast effect of the Mk14 HC shell was significant enough that it was reported to incapacitate infantry within 500yds, defoliate trees within 300yds, kill exposed infantry within 250yds, level trees and light structures within 200yds (also destroy most aircraft), and even destroy MBTs within 100yds. This is roughly comparable to a WW2 era 2000lb bomb (or a modern 1000lb bomb).
 
Or, in other words, the USS Iowa during the mid-1980s had a greater than 50% chance of destroying a tank at 42,345 yards with a single shell; or if it fired all 9 guns at the same target, greater than a 99.987003826% chance.
 
By all measures that was absolutely excellent accuracy, even if the guns were not as precise as one may desire.  That's just with 1980s technology.  Today, since you already would have to make all new guns and the ships to carry them, you could utilize developments such as Polygonal Rifling and ETC cannons to not only further increase the accuracy of the guns, but decrease time of flight or drastically increase the effective range of the guns well beyond 50 nmi without sacrificing payload; and that's without using science-fiction technology such as rail guns. Of course, it goes without saying that guided 16in shells would be essentially child's play to develop as well, considering they did it with the 8in MCLWG program to great success in the '80s.
 
But I digress, my point was that the Iowa's guns in their final configurations were accurate enough for all targets they were within range of. They were imprecise, yes, but VERY accurate.

 
I have nothing to add to this other than it further illustrates the amazing capabilities of the US battleship.
 
 
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[1]Ray D.May 12, 2023 at 10:37 PM
https://navy-matters.blogspot.com/2023/05/carrier-and-battleship-throw-weights.html?showComment=1683956277384#c8102893492469470189