Propulsion system of boat

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

• at least one propulsion machine including a drive source, and a propulsor configured to generate thrust with dynamic power transmitted from the drive source, the at least one propulsion machine being provided on each of both sides in a left-right direction with respect to a center of a hull;
• a trim angle adjuster configured to adjust a trim angle of each of the propulsion machines on the both sides in the left-right direction with respect to the hull;
• and
• a controller configured to control the trim angle adjuster, wherein
• the controller is capable of conducting trim support control and heel control, the trim support control causing the trim angle adjuster to adjust the trim angle to a trim support angle set in accordance with either a preset boat speed or a rotation speed of a propulsion machine, the heel control causing the trim angle adjuster to adjust the trim angle to a heel suppression angle set in accordance with an inclination in a roll direction of the hull to suppress the inclination in the roll direction of the hull, and
• in a case where a preset condition is satisfied, the controller conducts the heel control in addition to the trim support control, and causes the trim angle adjuster to adjust the trim angle to the heel suppression angle set with reference to the trim support angle of the propulsion machine.