Well I don't think you can actually get into the black boat as it is Team Plasma's. I'm not sure though but it doesn't seem like you can.
traveling
It's Team Plasmas boat!
You can't.
go on it and find out.
in castelia city, city with boat to victini
To take team Plazma to liberty island.
I have a feeling it is the boat u ride to the p2 lab for the genesect event.
It doesn't do anything that I am aware of, as it is Team Plasma's boat which they would use but it doesn't do anything and you can't board it.
The black boat that can be found located to your left on Prime Pier in Castelia City does not go anywhere and serves no purpose in the game.
after getting the ticket, talk to the boatmaster at the docks
You can't. It belongs to Team Plasma, but it doesn't really do anything.
You go to the final dock in castelia city and take the boat. You have to take out team plasma on the island