RC boats are made out of a variety of materials, but they generally fall into three groups: plastic; composites, such as fiberglass or carbon fiber; and wood.
Brushed motors use a rotating switch called a commutator to periodically reverse the current direction in the coil, switching that side of the armature to attract or repel the fixed magnets in the motor.
Brushless RC boats use brushless motors. The quality of a brushless motor is superior to that of a brushed one, and it will last longer as a result. Brushless motors are often more costly than brushed motors due to their improved quality and performance.