Watch the scenes that take place, once they are done talking head towards the back of the ship. Go through the door way to find Steiner. Approach him and talk to him, when they are done head towards the cabin at the end of the deck. Zidane will take control of the shop and turn it towards Lindblum. Black Waltz No.3 jumps onto the deck and, you guessed it, you have to fight him!
---Black Waltz No.3---
This battle much like the last, is very easy. Black Waltz uses mostly Fira to deal elemental damage to your party. Vivi is in his Trance for this battle which allows him to double cast his black magic spells. Use Steiner's Magic Sword abilities as usual and have Zidane stealing. If you need to heal have Zidane use a potion on a party member, concentrate on having Vivi and Steiner dealing the damage. Continue attacking with Vivi and Steiner and the battle will end in no time.
Once the battle is over some scenes will take place and you will be taken to Lindblum Castle.