If you put an offset on your sonar, did you give it a positive offset to read actual water depth or a negative offset to watch the depth below your outboard prop?

Enter a positive value to display the depth from the waterline to the bottom.
Enter a negative value to display the depth from the keel to the bottom.

I didn’t do a good job with my initial question. I put a positive offset in so that I could see true water depth. The lake I fish can have some very shallow spots in unexpected places so I wondered if I’d be better off to use a negative offset to measure the depth at the bottom of my prop. Just wondering what others do.