The Design A-150 was the last design of battleships made by the Imperial Japanese Navy. Design studies for this new class began in 1938 with the idea being to build battleships that would even dwarf the Yamato-class and that would outclass anything that the U.S. or British Navies could build in case the specifications of the Yamato-class where revealed.
The initial plans were calling for ships that would displace over 90 000 tons with an armament consisting of 8 or 9 510 mm guns in twin or triple turrets. This would have been completed by a secondary battery consisting of multiple dual-purpose twin turrets with 100 mm guns.
The armor protection would have been just as impressive with what could have possibly been a 460 mm main belt.
The design was later revised as it was judged too large and too expensive so it was brought down to the size of a Yamato-class. This version would have kept the 510 mm guns but this time, limited to 6 guns in 3 twin turrets. The armor was also be brought down to the 410 mm main belt that was already present on their predecessor. This design would have basically been a modernized version of the Yamato-class and if Japan ever went through with it, they would have most likely completed already laid-down hulls. Of course, this implies that Japan would have kept building Yamato-class ships but since war broke out, such work was delayed to focus on smaller ships and carriers.
For as much as we know, 2 ships were planned to be built with the first “Number 798” that would have been built in Yokosuka, in the same shipyard as Shinano and “Number 799” in Kure.
The biggest problem of this design is the limited information on it. At the end of the war, the Japanese Navy destroyed a lot of documents on possible designs they worked on and this included the A-150 design.
For the guns themselves, 2 guns and a gun mount were ordered at the Kure Navy Yard in June 1941 but construction was halted with the start of the Pacific War.
In World of Warships, the Yashima presents what would have been the “Modernized Yamato” A-150. She carries 3 twin turrets with 510 mm guns and a secondary battery with a mix of 155 mm guns and 100 mm guns. For the anti-air, it’s a bit awkward because she is armed with both 40 mm AA guns that were copied from stolen 40 mm Bofors and the completely obsolete 25 mm AA guns that were as effective as insulting the pilots of enemy planes. Then again… It’s not the first time that we see that kind of thing in the game.
Another thing, the Yashima has the “Battlecruiser” dispersion formula that can be found on Alaska, Stalingrad, Georgia or Thunderer for example.
These guns are also supposed to have a new unique gun sound and I hope that it will actually sound like you are shooting 2 tons heavy shells at the enemy.
The Yashima presents almost the same armor scheme as our beloved Yamato. There are a few differences that I will detail during this small analysis.
The bow section
The bow is protected by 32 mm of armor with the exception of a part of the deck that is 50 mm thick. This 50 mm section will at least provide some additional protection against HE shells from cruisers in general.
For the citadel’s athwartship, it’s the same as Yamato with the infamous cheeks. The lower part is 350 mm thick and heavily sloped and the upper part is 340 mm thick, also with a slop that can prove itself to be useful against penetrations through the bow.
For the cheeks, I guess that by now, everyone knows how they work. Wait for the ship to be a bit angled and the AP shells from the large-caliber guns will be able to go through the bow and then penetrate the angled plates on each side.
Above the citadel, there is a small 25 mm casemate on each side of the barbette.
The middle section
The deck of the Yashima is 57 mm thick which means that most HE shells from cruisers will shatter outside of the ones from the British 234 mm guns or from supercruisers and German cruisers using IFHE.
The sides are only 32 mm thick which means that even though they are quite thin, they won’t protect the ship from HE shells of cruisers.
For the main belt, it’s 410 m thick which is very good and it’s sloped at 19° to increase the effective thickness.
For the horizontal protection, outside of the weather deck, she only has her main armor deck. It is 200 mm thick except for the sloped sides that are 235 mm thick. This means that she is protected against AP bombs of the Enterprise and the Shokaku but Hakuryu will still be able to score citadels reliably.
The stern section
For the stern, it’s the same as the bow. The biggest portion is protected by 32 mm of armor except for the deck above the hangar that is 50 mm thick.
The citadel’s athwartship is also the same as the one at the front. 340 mm upper part and 350 mm lower part with the big cheeks on each side. As you can see, the steering gears are also protected by 350 mm of armor.
For the superstructure, there are some small differences with the Yamato because of the different secondary and AA armament but overall, it’s not smaller or bigger. This superstructure is protected by 19 mm of armor except for the barbettes of the 155 mm secondaries that are 75 mm thick and for the funnel that is 50 mm thick.
That funnel is actually quite different from the one on the Yamato and Musashi. It is going inside the ship and goes all the way to the deck level whereas, on the Yamato, it stops on the “floor” of the superstructure. The barbettes of the 155 mm secondaries are also connected to the citadel deck while on the Yamato, they are stopping on the weather deck.
The turrets have a few differences with those of Yamato. The face remains the amazing plating of 650 mm with a 45° slope. The sides are for the first part 250 mm thick and for the second part 225 mm thick compared to the constant 250 mm on Yamato. However, while on Yamato, the back of the turret is only protected by 190 mm of armor, on Yashima, it’s 250 mm thick.
For the roof, the Yashima has better protection with 290 mm of armor with the exception of the backend that is only 270 mm thick. On Yamato, it’s a constant 270 mm of armor.
Finally, the barbette is 510 mm thick which is more than enough to resist most AP shells that could possibly hit it.
For now, I’m slightly interested in how the Yashima could possibly perform. The thing is that the guns don’t gain any overmatch capability compared to the Yamato (unless all of sudden, ships with 35 mm external plating appear) and the alpha damage per volley is lower (116 400 vs 133 200). Also, the Yashima has the problem of having a much longer reload of 35 seconds. However, the ship has an absolutely ridiculous penetration power that beats every other battleships in the game. There aren’t many platings that can effectively resist her.
When it comes to the super high armor threshold of 170 mm… for now, I will wait because I highly expect that value to go down. It basically means that the ship will get overpenetrations very often on anything that isn’t heavily armored which… isn’t very good, especially with only 6 guns.
Also… when I see her secondaries, I’m almost tempted to meme around with a secondary build just to experience having a Harugumo strapped on each side of the ship.
Now as a side note, when I was looking at her 3D model, I found this:
It’s definitely an easter-egg and not just a random pattern. My personal guess was that it’s a coastline somewhere but I really can’t find something that corresponds.
If anyone on Reddit knows what/where it could possibly I would really appreciate knowing the answer.