A speed at which the vessel does not produce a wake
This is the speed of the engine with the following conditions: the transmission is in neutral (or park in automatic transmissions), the engine is fully warmed up, the choke butterfly is fully open, and there is no extra accessories in operation (i.e., air conditioner, radio, lights).
The slowest possible speed necessary to maintain steerage, but in no case greater than five miles per hour
The slowest speed at which it is still possible to maintain steering
Minimum speed that will maintain the steerage of a motorboat.
Slowest possible speed needed to maintain steerage and maneuverability
This refers to how fast the engine runs when idling. It can usually be adjusted by turning a screw on the carburetor throttle linkage, or by turning an air bypass screw on a fuel injection throttle body. On many newer cars, however, it is computer-control
The speed of the engine at minimum throttle and the engine in neutral.
The speed at which an engine idles in revolutions per minute (rpm), usually between 600 and 850 rpm. The idle speed is specified on the under-hood emissions decal.
Idle speed is the minimum operating speed (generally measured in revolutions per minute, or rpm, of the crankshaft) of a combustion engine. At idle speed, the engine generates enough power to run reasonably smoothly and operate its ancillaries (water pump, alternator, and, if equipped, other accessories such as power steering), but usually not enough to perform useful work, such as moving an automobile. For a passenger-car engine, idle speed is customarily between 600 rpm and 1,000 rpm.