Curt,

That should indicate the normal operating range from idle up to maximum rpm.

So often, what a manufacturer has to say about his engine, rpm wise, is not reliable. The maximum attainable rpm listed by any manufacturer is completely unrealistic. The engine would have almost no torque at that speed.

A general rule would be to prop the engine, to turn on the ground, halfway between the torque peak and the horsepower peak.

I sure, with your experience with boat engines, that once you get started with airplane engines, you will know what sounds about right. However, with a boat engine, you are trying to turn the maximum rpm if you can get it up on the step with just the lower tip of the prop in the water?

Also, go out to the flying field and observe others and listen. Ask questions.

Good luck,

Jim