I need help with Xemnas!!!!?

I am at the battle when he is driving the dragon ship and Riku and Sora had to chase him first. Now, I was actually fighting him in the ship and he threw Sora off of it. I am jumping and gliding back to the ship, but it keeps knocking me closer to the black hole. How in the hell do I get back on the ship to end this gosh awful thing?