And because I have no ability to restrain myself when it comes to boats, here is the story of the TTL Yamatos. Part of it is taken from my previous TL, so some may look familiar.
The TTL Yamato class draws heavily on naval designer Yuzuru Hiraga's design for "Ship No. 13", which was to be a class of four built after the Kii class battleships were built. They would have had a top speed of 30kn, a displacement of 47 500 t standard, and measured 900' x 101' x 29.2'. Armament was to be 4 x 2 18"/L50 guns.
Like many of Hiraga's designs, they feature powerful armament, armour that is very strong over a short citadel with long unarmoured ends, and high speeds. The one drawback to many of Hiraga's designs was the continued use of casemated rather than turreted secondaries.
Here are the OTL designs:
No. 13 Class Battleship
(credit to Wiki user "kallgan")
Hiraga's 1929 battleship design:
TTL, the IJN wanted these ships to counter the impressive new construction from the United States and Britain. The original (TTL) plan was to skip over the Kii class and build these ships. The WNT, which required that guns be limited to 16" rather than 18" led to a revision; the ships were to have twelve 16" guns instead of eight 18" guns, using the new 16"/L50 and installed in turrets of a new design.
Due to the tonnage restrictions and massive costs, a four-ship class was out of the question, but two were authorized, and were even assigned the names Izumi and Sagami.
However, the IJN of the time lacked a three-gun turret, and the need to lay down the ships and have them complete by the end of 1927 meant that running out of time was a real risk. With the 18"s reduced to 16", the need for an entirely new ship was lessened, and in the end, it was decided to modify the Amagi design with many of the features that would have gone into the Izumi class. The Great Kanto Earthquake sealed the fate of any further new ships being laid down.
In the mid-late 1930s, with the 1927-1937 Battleship Holiday coming to an end, several designs were tendered. The IJN's new battle plans, abandoning the idea of a decisive battle, required a departure from a slow but incredibly heavily armoured battleship with mixed turbine and diesel propulsion, to an extremely fast but heavily armed ship, with a short armoured citadel, and all turbine propulsion, using high-pressure boilers and impulse turbines. A forward bulbous bow also contributed to efficient high-speed cruising. The Yamatos also utilized a sharply pointed cruiser stern, unlike their American and British contemporaries.
The IJN's strategy, in the rapprochement era, shifted to the use of highly tactically mobile carrier task forces that would be able to fight in any conditions, day or night, and use high speed to escape a stronger opponent (namely the USN), and regroup for repeated attacks outside enemy range. Nearly all of the 1930s designs were shaped by this requirement: The carriers were built to be fast. The Agano class light cruisers were configured to serve as flotilla leaders for the screening destroyers, while the Tone class heavy cruisers were configured to carry numerous seaplanes for fleet scouting, the carriers' capacity devoted entirely to fighters and strike aircraft. The updated Kongo and then-proposed Ashitaka class battlecruisers would either lead detached elements or stay with the core fleet to add to the weight of fire.
The Yamatos' task would be to keep up with the carriers and lay down a thick AA screen (compared to an American battleship, they carried slightly more 40mm weapons but considerably fewer 20mm ones), and fight off any battleships or cruisers that came near the combined fleet. Their guns are optimized for long-range plunging fire, in order to keep challengers well away.
The Yamatos are based on the Izumi class, but with ten years of improvements. Secondaries are no longer casemated, and there are no torpedo tubes. The hull form has a cruiser-like block coefficient with lots of sheer and flare on the long bows to keep the ships dry. The tower-pagoda mast installation and raked funnel (not as raked as the second picture, more like OTL Yamatos) complete the quintessentially Japanese appearance.
Japan's other great naval designer, Kikuo Fujimoto's work was also incorporated into the final design. For further weight savings and a sleek hull form, the Yamatos were welded rather than riveted. Finalized dimensions are 1021' x 115' x 35.5' and 57 000 t light, 63 000 t standard. Main armanent is 12x 16"/L53 Type 0 41cm Naval Guns in four three-gun turrets, secondaries are 6x 155mm low-angle guns on the centreline double superfiring main armament, and 20x 100mm DP guns in five twin turrets per side. Light AA consists of up to 112 Type 1 Bofors guns in twin and sextuple mounts, and 20-30 20mm Oerlikon MG-FFS cannon in twin and single mounts.
The TTL Yamato class draws heavily on naval designer Yuzuru Hiraga's design for "Ship No. 13", which was to be a class of four built after the Kii class battleships were built. They would have had a top speed of 30kn, a displacement of 47 500 t standard, and measured 900' x 101' x 29.2'. Armament was to be 4 x 2 18"/L50 guns.
Like many of Hiraga's designs, they feature powerful armament, armour that is very strong over a short citadel with long unarmoured ends, and high speeds. The one drawback to many of Hiraga's designs was the continued use of casemated rather than turreted secondaries.
Here are the OTL designs:
No. 13 Class Battleship
(credit to Wiki user "kallgan")
Hiraga's 1929 battleship design:
TTL, the IJN wanted these ships to counter the impressive new construction from the United States and Britain. The original (TTL) plan was to skip over the Kii class and build these ships. The WNT, which required that guns be limited to 16" rather than 18" led to a revision; the ships were to have twelve 16" guns instead of eight 18" guns, using the new 16"/L50 and installed in turrets of a new design.
Due to the tonnage restrictions and massive costs, a four-ship class was out of the question, but two were authorized, and were even assigned the names Izumi and Sagami.
However, the IJN of the time lacked a three-gun turret, and the need to lay down the ships and have them complete by the end of 1927 meant that running out of time was a real risk. With the 18"s reduced to 16", the need for an entirely new ship was lessened, and in the end, it was decided to modify the Amagi design with many of the features that would have gone into the Izumi class. The Great Kanto Earthquake sealed the fate of any further new ships being laid down.
In the mid-late 1930s, with the 1927-1937 Battleship Holiday coming to an end, several designs were tendered. The IJN's new battle plans, abandoning the idea of a decisive battle, required a departure from a slow but incredibly heavily armoured battleship with mixed turbine and diesel propulsion, to an extremely fast but heavily armed ship, with a short armoured citadel, and all turbine propulsion, using high-pressure boilers and impulse turbines. A forward bulbous bow also contributed to efficient high-speed cruising. The Yamatos also utilized a sharply pointed cruiser stern, unlike their American and British contemporaries.
The IJN's strategy, in the rapprochement era, shifted to the use of highly tactically mobile carrier task forces that would be able to fight in any conditions, day or night, and use high speed to escape a stronger opponent (namely the USN), and regroup for repeated attacks outside enemy range. Nearly all of the 1930s designs were shaped by this requirement: The carriers were built to be fast. The Agano class light cruisers were configured to serve as flotilla leaders for the screening destroyers, while the Tone class heavy cruisers were configured to carry numerous seaplanes for fleet scouting, the carriers' capacity devoted entirely to fighters and strike aircraft. The updated Kongo and then-proposed Ashitaka class battlecruisers would either lead detached elements or stay with the core fleet to add to the weight of fire.
The Yamatos' task would be to keep up with the carriers and lay down a thick AA screen (compared to an American battleship, they carried slightly more 40mm weapons but considerably fewer 20mm ones), and fight off any battleships or cruisers that came near the combined fleet. Their guns are optimized for long-range plunging fire, in order to keep challengers well away.
The Yamatos are based on the Izumi class, but with ten years of improvements. Secondaries are no longer casemated, and there are no torpedo tubes. The hull form has a cruiser-like block coefficient with lots of sheer and flare on the long bows to keep the ships dry. The tower-pagoda mast installation and raked funnel (not as raked as the second picture, more like OTL Yamatos) complete the quintessentially Japanese appearance.
Japan's other great naval designer, Kikuo Fujimoto's work was also incorporated into the final design. For further weight savings and a sleek hull form, the Yamatos were welded rather than riveted. Finalized dimensions are 1021' x 115' x 35.5' and 57 000 t light, 63 000 t standard. Main armanent is 12x 16"/L53 Type 0 41cm Naval Guns in four three-gun turrets, secondaries are 6x 155mm low-angle guns on the centreline double superfiring main armament, and 20x 100mm DP guns in five twin turrets per side. Light AA consists of up to 112 Type 1 Bofors guns in twin and sextuple mounts, and 20-30 20mm Oerlikon MG-FFS cannon in twin and single mounts.
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