Living at the place of many waters
I think the forceps where you want to be was the ideal depth check idea. Or the ratio 4 out = one down. Why do math if you don't need to. Just as a surveyor I like to play with angles and math. I'm sick, I know. My wife calls me "her other special needs child", besides her students. But I could teach you, at CC I teach this to kids who didn't take it or didn't learn it in high school.I’m not quite that fancy, but I want to be.
Tool for reading angle. Line tube up with line, then adjust level bubble, which works on gravity, to find angle from hoizontal.