... to run up to 12 hours at 200 below max RPM". In other words, don't push it further than that for longer than that. He defined Max RPM as a variable that will change with boat loading and whether the bottom is clean; but it's just as fast as it will run flat out, then back it down 200 RPM.

Given that limit, I could run at whatever speed seems right for the circumstances without worrying too much about it.