How deep does this crank run?

[lefty]

I've already forgotten which of my first batch of crankbaits is designed to run deep and which is designed to run shallow. I can guess from the size and angle of the bill, but aside from that, what methods do y'all use?

I'd heard a suggestion to write the running depth on the bill... I tried using a normal sharpie, and after one day's use, my experiment is a barely-visible shadow. I've got an etching pen (not electric) that won't wear off, but I'm afraid it would affect the run of the lure. Should I look for a paint pen, or is there another better way?

Thanx - lefty