Carburetor incorrectly adjusted(Nitro Vee) Readjust carburetor to factory break-in settings Prop is damaged Replace prop. Refer to your parts list or exploded views for the correct part number. Loose or broken driveshaft or drive cup Refer to your parts list or exploded views for the correct part number. Incorrect outdrive angle Set outdrive angle in line with bottom of boat. Vacuum created between boat and water Drive the boat with quick right and left movements to break vacuum.