Yeah, I spent last week working with a buncha Engineers who are stuck in the Imperial system because everything is made in the US, and is thus in inches and feet. Buddy would say, "I think it's about 6 feet deep", or "It's 31 inches below the surface" and I would sit there converting that to metric in my head so I could say "Yes, deep enough," or "No, add more water." (Since of course I've worked out the operating parameters of my sonar in metres, not feet!!!)