A 91 Strictly according to RAW, zone of truth wouldn't move with the ship. However, this is of course most likely not intended, and there are rules for several other spells which GMs are encouraged to use as guidelines also for similar spells and similar large vehicles not specifically detailed in these naval combat rules.

TL/DR: Ask your GM, but zone of truth should move with a ship if going by the RAW for similar spells.

(FWIW, I'd personally definitely rule that zone of truth and similar moves with a ship, meaning the spell is "anchored" to the ship's deck rather than the usual more static geographic location.)