"Every ship has three AI's. Due to the radiation and interference, all three suffer lapses in sanity. They're encased in lead, but the sensors are mostly wide open to radiation. Often, they 'hallucinate' from from observing the outside world with faulty sensors, so they often vote as to whether or not an input is actually real.

"A fourth AI is purposefully kept dormant. He's a bit single minded and his only purpose is to find a planet and touch down. If the other three ever can't agree or have a moment of clarity in which they realize they've become unstable, they deactivate and activate him. He regularly reloads from scratch, forgetting his previous incarnations and spends a majority of time validating the coordinates his previous incarnation left for him, making course adjustments, and ensuring the humans don't prevent him from saving them..."

I would read that book...

Maybe you should write it instead. Then we can read it. :)

Interesting to compare Frank Herbert's Destination: Void:

The crew are just caretakers: the ship is controlled by a disembodied human brain, called "Organic Mental Core" or "OMC", that runs the complex operations of the vessel and keeps it moving in space. But the first two OMC's (Myrtle and Little Joe) become catatonic, while the third OMC goes insane and kills two of the umbilicus crew members. The crew are left with only one choice: to build an artificial consciousness that will enable the ship to continue. The crew knows that if they attempt to turn back they will be ordered to abort (self destruct).

https://en.wikipedia.org/wiki/Destination:_Void