Among Huai Shi's many different experiences, even compared to every other vehicle, the Solar Ship's Deep Dive was an exceptionally unique experience.
Of all means of travel, the Hell Train Tuna in the school district was actually the most stable and fastest. It provided point-to-point travel without any interference, but only within the range of The Tower's light on the Rainbow Bridge, and only if a station of equivalent specifications had been established and a beacon erected at the destination.
It was essentially a Hell high-speed rail system that required constant resource investment to maintain: safe and convenient, except that when the War of All Realms arrived, nearly all routes had already been temporarily abandoned.
By comparison, airships were more flexible, but their defenses were too fragile to perfectly adapt to Hell's unknown changes. The original plan had been to find a suitable place to store or simply abandon it after entering regions below Depth 10, then transfer to the Chariot of Destiny.
Although Russell had made many contingency plans, including guides in Hell and ways to deal with all kinds of unexpected situations, he had not accounted for Raymond's advancement.
On one hand, the Chariot of Destiny's defensive capabilities and inherent abilities were sufficient to complete the mission. Moreover, once a mature vehicle was rashly upgraded, the resources and maintenance it required would become even more enormous. They would have to increase the number of team members, losing the mission's original secrecy.
On the other hand... no one had expected that Huai Shi's bastard would have so many enemies in Hell, or that he would be so good at drawing aggro. Even more absurdly, they had been blocked the moment they set out, completely exceeding the Chariot of Destiny's ability to handle the situation and forcing an emergency upgrade.