I don't know why, but when I tried to give a ship a navmesh agent, when played it suddenly flipped From this Normal Ship To this Flippedship. And when I check it, it is because the area of the navmesh agent is on top of the ship like this.NavMeshAgent area for the ship. Is there anyway to change it?
PlayerUnitShipRoot <----NavMeshAgent
PlayerUnitShip <----Mesh Filter & Mesh Renderer
Create a new GameObject (PlayerUnitShipRoot).
Put your orignial model (PlayerUnitShip) under it.
Add a NavMeshAgent on PlayerUnitShipRoot.
Move and rotate PlayerUnitShip to a proper position.