But the head-popping ghost was left behind.
Why don't you talk to him?
If you promise not to hurt him, he'll talk freely.
Just ask him the right questions.
Run through your dialogue options to learn the LeChuck intends to marry Elaine on Melee Island.
Now you just need a way to get to Melee Island.
You can take your ship, but if you destroyed it with the catapult, Herman Toothrot will show up and volunteer his.
Ask him to take you to Melee Island.