Here is an interesting piece of History that few know about. A new commander, on his first mission, meets an aircraft carrier, being moved before it was finished, out of Tokyo bay.
This new skipper, was able to get in position on the largest non Nuclear aircraft carrier ever built. It is a sister ship to the IJN Yamato (the largest Battleship ever built), that was converted into an aircraft carrier, when Japan lost most of her carrier fleet. They understood that the Battleship was obsolete, and the new power on the ocean, was the Aircraft Carrier. This is why they began the conversion, and they would have had a formidable aircraft carrier. When you build an aircraft carrier, on the carcass of a Battleship; you start with really good bones! With a real crew on her, and a screen of fighters over her, she would have been a hard target for sure
Here is a picture of this Massive ship:
The information on this ship is sketchy.
Here is the article:
https://www.warhistoryonline.com/instant-articles/uss-archerfish-sinking-shinano.html?utm_source=getresponse&utm_medium=email&utm_campaign=warhistoryonline&utm_content=[War+History+Online]+Daily+Dispatches
When Commander Joseph F. Enright Managed to avoid her escorts, at significant risk to the USS Archerfish herself; he fired six torpedoes, with a wide spread intended to allow one to pass ahead, and one to pass behind.
This was standard practice in case the speed was estimated badly, this would allow more torpedoes to hit, in a real world situation. The USS Archerfish had estimated the size of the ship, through their periscope, but set up for a normal fleet carrier to be cautious. They were surprised to hear six hits, where the most should have been only four. The six hits supported the size from the periscope measurements, which was what went into the ship's log.
On the IJN Shinano the Commander was temporarily assigned to the not yet finished ship, tasked with moving it to the inland sea; to protect the not yet completed vessel, from ever increasing air strikes. He had a Huge vessel, heavily armored, and some of the best destroyers in the IJN! Her sister ship the IJN Musashi, took 19 torpedo hits in combat; before she finally sank. Knowing this fact, he made a fate filled decision, after taking the full spread of Archerfish torpedoes; he decided to continue on to the China Sea. This was a fatal mistake, because if he had turned, and grounded the vessel, she could have been re-floated and saved. By the time he realized he did NOT have the professional damage control team that the IJN Musashi had, it was too late; he had instead, dock workers, and ship builders. The IJN Musashi was doomed to sink in deep water, and her temporary commander was destined to go down with her!
Commander Enright did not do much better. When he reported back, they told him that he was just inexperienced and that no ship was that big! They gave him credit for damage on a normal fleet carrier. He never knew his vindication because his ship was sunk before the end of the war, and the increase in tonnage was awarded posthumously. I am sure he would have been amused to know it though. He got the largest kill in submarine History, and they did Not believe him!