Aleister is not one to procrastinate. In this regard, she is much sharper than "Aiwass."
Once she sets her mind on a goal, she acts without hesitation, with lightning speed—
She flew back to Leipzig with Leviathan, transformed back into Beyard, donned the black robe only worn by professors from the Spirit Summoning Tower, and boarded the ship.
Though she brought a fearsome and terrifying monster onto the ship, for Necromancers, having monstrous servants by their side seems not out of the ordinary.
Even facing more horrific monsters would seem reasonable; the only real issue would probably be whether Avalon's customs would permit it to enter the country... But that was no concern of the captain's. So the captain, happy to take the money, didn't bother to give any warning.