The Immortal Ship capable of long-distance travel in the Star Sea is extremely precious, so precious that not even a Longevity Emperor's Weapon might possess such capabilities, because the endless Star Sea harbors too many dangers. You might frequently encounter lone Star River Monsters like the Sky God, and if the Immortal Ship isn't sturdy and fast enough, it might shatter into pieces at first contact with these creatures.
Of course, this conclusion is drawn based on the technological civilization of the Celestial Profound Realm. It's possible that some advanced civilizations following a technological path have means of resisting the Longevity Realm using ordinary materials.
But these matters have nothing to do with Bai Yu.
Hmm, Bai Yu believes that she might not leave the Celestial Profound Realm many times in her lifetime, and keeping such a Jade Wave Shuttle Immortal Ship in her possession is indeed somewhat wasteful.
