When Moonshadow, Ira, Sunflower, and Frodo are released from The Zoo, they are teleported into the middle of space, and The Decrepit is instantly created (or teleported) around them.
Moonshadow takes over as the ship's captain, as the others are less interested in such Romantic ventures. The ship is controlled by a computer named Cornelia-17, which is fussy but brave. Moon is constantly losing and regaining The Decrepit.
The ship is fairly large but can be run with a minimal crew. It is capable of interstellar flight.
They randomly fly off in search of adventure, eventually entering the Kickapoo Cluster, which other ships are leaving en masse. They hear there is a plague, and Ira tries to take over and leave, but Cornelia won't let him, being loyal to Moon. Unfortunately Sunflower dies as they investigate.
They fly to Gimmegimme, a mall world, to provide a funeral for Sunflower. Moon ends up being less loyal to Cornelia than she is to him, and he sells The Decrepit to a pawn shop to pay for Sunflower's funeral. Ira doesn't know this, and gets Moon thrown in jail, thinking he can take back The Decrepit and fly off. Once he finds out that it's pawned, he breaks out Moon and makes him work, to buy The Decrepit back. This doesn't work and they end up both getting arrested.
They take military duty instead of jail, and luckily find that The Decrepit was purchased by the army and is their squad's new ship. They fly off to Bingbangboom with Sgt. Chesterbarrel, Horntoad, and Rigarollo for a secret mission. However when they return to their ship afterwards, they discover that it is missing, and continue on by other means.
Much later, Moon is once again in need of a ship, and looks for one at Eloise and Poodleoo Tittletat's used rocket lot. To his amazement, he finds The Decrepit once again. It had been stolen by intergalactic rocket thieves. Unfortunately, they also took the logic chips out of Cornelia-17, and she was loopy ever after.
Moon buys it back and from that point on retains ownership of The Decrepit. He uses it to rescue Ira from Mobidiah Unkshuss's mind control, visit Lord Gaylord's destroyed compound on Pillbox, and stop off at the Interplanetary House of Tarts, He is then captured, but the Decrepit is towed back to Gimmegimme, and he takes it back for his final revelation on the World of Mists.
It is unclear whether he still possesses The Decrepit in middle age or later life.