The Battle of River Plate was 22,000 tons of Allied cruiser versus 12,000 tons of German cruiser, so the Allied victory isn’t a great surprise.
My personal opinion is that the Deutschlands represented the high point of German fleet unit design, and it was all downhill after that. Hipper is illustrative. She was huge–the largest heavy cruiser class to see action in WWII, 2000 tons larger than Deutschland. Yet her armor scheme was a joke. A 20mm deck–that’s splinter protection, not an armor deck!

Alas for you all, alas and alack, for I have no qualms about responding to each and every post in a thread that has lain dormant for three years.
My personal opinion is that Yamato would be the likely victor over Iowa. When these “duels” come up for discussion, they usually imply fighting conditions that favor the American ship–that is, where her radar can give her the biggest possible boost. In that setting, she would have at least a reasonable hope to win, but across the full range of plausible scenarios, things look less hospitable to the USA.
If we take crew quality into account, however, I might be more optimistic for the red white and blue. If we had reliable statistics on the frequency Yamato’s gunnery practices, we might all have a good laugh. I don’t believe she ever had to have her guns replaced for wear.
On the other hand, the USN never settled on reliable stats for Yamato, and the official range band preferred for a fight between Iowa and Yamato was actually a highly disadvantageous one.
Iowa has no useful Immune Zone against 46cm shells. Yamato, on the other hand, has a good Immune Zone inside of, oh, 32,000 yards.
Montana would likely mop the floor with Yamato or any other opponent. Montana was, in my opinion, the most powerful bruiser to be seriously considered for construction in any battleship navy.
The USN did not hold that speed offered any appreciable tactical advantage to a ship unless it wanted to run away.
I may be wrong, but I believe the broken 16in shell displayed aboard USS Massachusetts is the one that struck Jean Bart’s turret and rebounded into Casablanca city. The reason the base is broken is probably because the shell was subjected to base slap when it struck the angled armor–that is, the shell was subjected to a whipping motion. A second shell was also broken when it struck the edge of a barbette. It’s possible in both cases that the fuze ignited the burster but the broken case allowed it to fizzle rather than explode. Maybe that’s why it looks melted.
Yamato’s weaponry was a linear descendent of the 13.5in guns of ships like HMS Iron Duke, Lion, and Tiger. That puts it in the same family with the famous 15in gun of Warspite and Queen Elizabeth, often regarded as the finest battleship gun ever. The Japanese made no effort to use heavy shells or extreme velocities, and the available information is that the 46cm gun fired with acceptable accuracy and regularity.
Bismarck and Tirpitz were not especially good designs, and I have a specific objection with their turret armor which was penetrable by EVERY battleship gun of that period, firing from ANY range. However, against a heavy cruiser like Des Moines, Bismarck was perhaps the best-armored of all modern battleships. That does not mean she’s immune to having her topside systems turned to origami by rapid-fire 8in shells. Des Moines can fire to a maximum of 30,000 yards. That means Bismarck can engage her with optical fire control, assuming suitable visibility. Depending on the atmospheric conditions, Des Moines may not be able to spot her shells out past (maybe) 28,000 yards. The Battle of Empress Augusta Bay shows what happens in the absence of long-range spotting.
Scharnhorst was a truly poor battleship design, but she has a significant size advantage over Alaska. Alaska has to outshoot Scharnhorst in order to win that duel.
A 46cm near miss on Iowa can do more than damage the FC. Japanese shells were designed for controlled underwater trajectories. The degree to which one can control underwater trajectories is not great, but Yamato would have a better chance of under-belt penetration.
I have been told that Iowa’s 5in guns were harder on the ears than her 16-inchers. A very sharp crack! from the smaller guns.
Furious was designed for two 18in guns. I don’t recall offhand if both were mounted. A few monitors were also fitted with the 18in gun during WWI.

Indeed, If you read about the RN’s tentative fleet plan you quickly realise that the Z-plan would not have achieved any great superiority at all.

The Germans knew they would never gain superiority over the RN, which makes you wonder–what did they think they were accomplishing? The fact is that even the Germans were unsure what their largest fleet units were intended to do. No kidding.

Let’s not forget the Royal Navy’s attack on Taranto by Carrier Aircraft. Really, the first of its kind and gave the Japanese the idea to strike Pearl Harbor.

There is a real link between Taranto and Pearl Harbor in that the Japanese plied the Italians for technical information on the outcome, but the Japanese did not need anyone to give them the idea. The first mention of attacking the US at Pearl dates from 1936 which, I believe, predates the original Taranto planning by a year. It should be remembered that the British were planning a torpedo-plane attack on a German base in 1918. I think this was examined in a recent Warship annual.

I’ve heard it was the third largest. I don’t know what that means, though.
People will look at you funny when you tell them the Flowers were the decisive class in the war.

You point out an important factor, and the thing that amazes me is the German persistence in the face of the most glaring, screaming lesson on unproductive naval allocations. There is a very reasonable argument that Germany’s battleship fleet caused the country’s defeat in World War I. It’s a sad tale really. Ostensibly the battleship fleet was intended to guarantee a partnership with Britain, but it had the exact opposite effect–you’d have a hard time finding a policy to match such utter failure. By the time Wegener published his paper on the inherent inability of any German navy to challenge the British, the damage should have been obvious. (This was during the war.) The fellow hand-picked by the high command to refute Wegener was a promising young officer named Raeder. I guess Raeder did such a good job of countering Wegener (in his own mind, anyway) that, 20 years later, he once again ignored the warning and pursued construction that could not have prospered in a war with Britain. maybe he still harbored hopes of fighting France alone. Who knows?
It’s interesting to consider what a U-boat increase might have gained, though I suspect the first effect would have been increased attention to ASW by Britain.

There was a Hipper-class cruiser, Seydlitz, that began conversion for carrier duty and ended the war incomplete. GZ, however, was a purpose-built ship considerably larger than a Hipper. More like Illustrious- or Yorktown-sized. When all the bulging and such were completed, she neared 28,000 tons, nearly Essex-sized.
By the way, the story about GZ sinking accidentally on the way to Russian captivity is inaccurate, even though I’ve been hearing it since I was a kid. She was expended by the Soviets in weapons trials.
Fighter vectoring was no simple task in those days, and even the fleets experienced in such things were often successfully snooped by patrol planes. The best way to vector a fighter is by radio, and planes create a radar echo too, so GZ’s presence might actually have made the Germans easier to track.

I’m surprised I missed that previous thread, as this sort of topic is right up my ally.
There are two good sources on GZ in English. One is Whitley’s German Capital Ships of World War Two; though it deals mostly with armored ships and battleships, it has a section on carriers. It may still be in print and is an excellent source. The other is Siegfried Breyer’s book from AJ Press (parallel Polish and English) not to be confused with the little paperback from Schiffer Books. The definitive source is usually considered to be Israel’s German-language book.
GZ’s flight deck was not laid out to permit rolling take-offs. All planes had to use the catapult system which included a trolley system. Unfortunately, the catapult system could launch only eighteen planes before it had to be recharged, which took, I don’t know, almost an hour. (That’s from my memory.)
Looking at the previous thread, I can add a bit.
The flight deck equipment supplied to the Italians was that intended for Carrier “B,” GZ’s incomplete sister. The Americans had a good look at it after the Italian surrender. Their verdict was that it was not only inefficient but hazardous.
The name “Peter Strasser” was never assigned to Carrier “B.” While that would have been a perfectly good name, it is pure speculation, and there is no way to tell what name the ship would have received.
The Stuka variant developed for the carrier was the Ju 87C.
It is correctly pointed out that a carrier didn’t suit German naval needs, but then, neither did battleships like Bismarck. (First sortie = last sortie = someone had blundered.) The German navy was coming out of a long slumber and lacked direction. The late-1930s was a period of explosive growth for an organization that had been gutted by Versailles, and Hitler’s policies did not exactly clarify what naval policy should have been.
Illustrious’s survival of her dive-bombing experience had little to do with her flight deck armor–only one of the bombs actually hit her flight deck armor, and it penetrated as deeply into the ship as the other bombs.
I have not seen the article in Air Enthusiast no 92 (Mar/Apr 2001) and would very much appreciate if someone could supply a pdf.