There are four different watercraft, each with differing properties. If you choose the Custom setting when you select a watercraft, you can further adjust the properties of your watercraft.

HANDLING	This determines the ease with which your watercraft can turn. When set to LIGHT, you need only to tilt lightly to turn. When set to HEAVY, you must tilt farther to turn.
ENGINE	This determines your acceleration and maximum speed. Sliding the bar towards DASH increases your acceleration. Sliding it towards TOP END increases your top speed.
GRIP	This adjusts the amount of resistance your watercraft creates on the water. Sliding the bar towards LOOSE increases your speed on water but reduces your grip on turns. Sliding the bar towards TIGHT increases your grip on turns but lowers your speed on water.