To verify the identity of the ship, he checks the engine serial number, which thieves often forget to remove. If he can get private access to the engine room, Hardberger carries a glass vial of magnetic powder to sprinkle on the hull where the ship’s original or “build” name has often been pried off. The shadow of the name still shows up because welding it off changes the metal’s valence, which makes the magnetic powder adhere differently.
