Reach your modifed thirds turning pressure in a wreck; start reeling in your line and make a mental note of how far you penetrated by looking at the illuminated color pattern of your line markers, and also look around to see where you are presently inside the ship.
Seems simple and apparently utilitarian to me.
...or you could tie a knot in your line before rewinding it. You can measure how much line there is before the knot later, and there is nothing to remember.