Since the platforms on both sides of the ghost ship are equal in height, it is possible to simply Item Slide across.
The battle inside the Ghost Ship can also be skipped simply by performing Leaf Pumps and grabbing the ledge on the other side.
In a 100% speedrun farming rupees in the ghost ship is very useful. It is possible to reload the area by Ledge Clipping with a bomb and voiding OoB. The setup for this is to Wall Target the chest and then wedge Link into the corner between the door frame and the left ledge inside the main room. Then pull out a bomb and drop it with ZR, followed by using the leaf to blast wind in front of you. Right after doing this, perform a sidehop and use the leaf to fly forward and maneuver Link to face the ledge and grab it. From here perform a Ledge Clip and simply fall.
Much harder, but it is also possible to clip OoB to reload the area using a L-Slide Clip.
The Ghost Ship only appears at night, so manipulating the Day/Night cycle is crucial in a speedrun in order to skip having to obtain the Song of Passsing or needing to wait for the Ghost Ship to appear. Click here to see how the day/night cycle works in Wind Waker.