Propulsion system of boat

A propulsion system of a boat, the propulsion system comprising:

• a propulsion machine including a drive source, and a propulsor configured to generate thrust with power transmitted from the drive source, the propulsion machine being provided on a hull;
• a trim angle adjuster configured to adjust a trim angle of the propulsion machine with respect to the hull;
• and
• a controller configured to control the trim angle adjuster, wherein
• the controller is capable of conducting hump control of causing the trim angle adjuster to adjust the trim angle of the propulsion machine with a preset trim angle lower limit value as a lower limit to suppress an inclination in a pitch direction of the hull, and
• in stopping conducting the hump control from a state of conducting the hump control, the controller causes the trim angle adjuster to adjust the trim angle of the propulsion machine in accordance with a state of the hull.