Markin your rope ?

[Slot Machine]

Agree on all points. I've used sharpie for years on both canyon and climbing ropes. It doesn't damage the rope. In fact, it might not even be there after the trip. I get half a season out of it on a climbing rope, but probably only one wet canyon.

I bet your mark comes off because you are not actually using a Sharpie. Kind of a noob mistake, but an easy one to fix.