The Bourbony concept of impounding the black ship was simply to post two guards there. It's not like they could lock the hangar doors seeing as how there were no front doors any more. These huge hangars were built to house airships in the first place, and on the possibility that an airship couldn't move backwards
out of the hangar (at least on its own), there were hangar doors at both ends.
Apparently these two gendarmes had been told about what your group had done to some extent, so Grimsby's presence lets you enter the hangar to board and inspect the black ship.
When Grimsby explains the situation to the gendarmes, a messenger is dispatched to Inspector Forget. Since she is busy with the exposition, she sends a message in reply.
quote:
"Mr. Grimsby: While it would be of immense value for Bourbony to have its own airship, we've done just fine without one up till now. Your efforts on behalf of the Crown and Country deserve greater reward than we could ever give you. Consider the black ship on loan to you and your group while you continue to pursue our common enemies."
--Inspector Coleen Forget
At that point, it takes about an hour to transfer any luggage from the
Falcon to the black ship, or from Maybelle's hotel to the black ship. And you are ready to go.
Once settled into the black ship and exploration is complete, you do find the name of the ship is
The Black Talon.