I had a look at all the Japanese heavy cruisers and apart from the Aoba and Furataka class they all have rare turret positions. Looking at the Myoko, Mogami and Takao class, they all have three turrets in front where there's always one masked by another one. (The Tone class is even worse, 2 masked guns). My question is, why did the Japanese designed it this way? Okay, the poor firing arcs are no problem when firing broadsight but there are times you can only fire frontal. making that extra (and second for the Tone class)) turret worthless. What is the idea behind those masked guns? why are they good for? And while we are there, Who was so ingenious on putting all the guns in front on the Tone class? Once again, great if you cross the T but useless when retreating. Same for the Fuso and Ise class battleships, why putting guns on a Q-position (midships is Q, isn't it?)?
If you look at battleships built before and during WWI, it was common to have turrets with limited arcs. Surely the most exaggerated example is HMS Agincourt which had seven centerline turrets. Did you know that Russia's Sevastopol class had four turrets evenly spaced along the hulls length, with no super-firing turrets, in order to ENLARGE the firing arcs. Not every navy had turrets that were sealed against nearby blast, so super-firing turrets could not actually fire over the turrets beneath them. If you want to increase firepower, there aren't too many options. One is to use bigger guns. This sounds simple, but it entails many technical hurdles and literally an exponential increase in weights. The other option is to increase the number of guns, and this means either more turrets or turrets with more guns. Triple and quadruple mounts, again, are a technically challenging matter with many attendant issues; for example, you can't simply put a quad mount in place of a twin mount without the hull collapsing--you've added a whole lot of weight and removed a whole lot of the strength deck. Also, the fire-control procedures in some navies work better with twin mounts. This last factor was so important to the Germans that, even after they mastered the technical challenge of triple mounts in their cruisers and battleships, they reverted to twin mounts in Bismarck and in the "M" class cruisers. The Japanese also had a preference for twins, though the underlying reasons remain unclear to me. Trivia: the only IJN ships to mount large triple mounts were those mounting triples originally meant for the Mogami class. That means the Mogamis, the Yamatos, and Oyodo. At a time when most foreign CA designs mounted eight guns in the conventional fashion, the Japanese decided they were going to go one better and add another twin mount. This makes the added forward turret look fairly reasonable--you have to put the extra turret somewhere--but the fact is that the original studies had only one aft turret and three forward turrets. It was an aft turret that was added later. Why? I have no idea. The Tones (and Oyodo) were a special case. Tone was intended to provide extra aviation facilities, so all the guns were jammed up in the front so the after section could house the hangars, catapults, etc. This would make her a great asset for fleet reconnaissance, at least in theory. Oyodo was a similar story, though her role was to scout targets for submarine squadrons. I guess we can add the rebuilt Mogami to the list, but I don't think the Japanese had much leeway in her case. Her aft turrets had been smashed, and I don't think there were any spares available. That's also why Aoba was running around without her aft guns for a while. If you look around at the WWII fleets, you'll find plenty of ships with masked turrets: France's Courbets and Provences, America's Brooklyns and New Yorks and Arkansas, the Soviet Sevastopols, and all those Japanese ships. Each case represents a specific set of factors, and you can have fun looking up each one.
