Watercraft propulsion system and watercraft including the watercraft propulsion system

A watercraft propulsion system to be provided on a watercraft including a hull, the watercraft propulsion system comprising:

• an engine including a cylinder block, an air intake channel connected to the cylinder block, an exhaust channel connected to the cylinder block, a supercharging device in the air intake channel, and a fuel injector;
• a propulsion unit to be driven by the engine and to apply a propulsive force to the hull;
• a rotation speed sensor to detect a rotation speed of the engine;
• an air intake pressure sensor to detect an air intake pressure of the engine;
• and
• a controller configured or programmed to compute a command fuel injection amount so that the engine performs a combustion operation at an air/fuel ratio in a lean-burn range according to the rotation speed detected by the rotation speed sensor and the air intake pressure detected by the air intake pressure sensor, and to drive the fuel injector based on the computed command fuel injection amount.