System and method for automatically controlling trim position of a marine drive unit

A system for controlling a trim position of a trimmable drive unit with respect to a transom of a marine vessel, the system comprising:

• a controller,
• a processor;
• and
• a memory storing instructions that, when executed by the processor, configure the controller to do the following automatically without requiring initiation by an operator of the marine vessel:
• retrieve from the memory a stored level trim position of the drive unit;
• receive an actual trim position of the drive unit;
• determine whether an absolute difference between the level trim position and the actual trim position exceeds a given threshold;
• determine whether at least two of a plurality of trim-to-level enable conditions indicate that an engine powering the drive unit is idling, wherein the at least two trim-to-level enable conditions include:
• (1) an actual speed of the engine is less than a given engine speed threshold, and (2) an actual speed of the marine vessel is less than a given vessel speed threshold;
• and
• in response to a determination that the absolute difference exceeds the given threshold and that the at least two trim-to-level enable conditions indicate that the engine is idling, send a control signal to trim the drive unit to the level trim position.