How to calculate working hour in rpm?

Question

my reading is 359 hour at 1800 rpm

Answer 1

describe more.  where did the 359 come from

Answer 2

An hour meter on a boat engine normally registers the time that the ignition is turned on. This is usually equated with the time that the engine is running. If you leave the ignition turned on after you shut down an engine, the time will continue to accumulate on the meter. I am not sure how you could measure time at certain rpm's ...

Answer 3

are you looking for fuel consumption at a certain rpm or a time frame