One of my spots in Nazeing just happens to correspond with the distance from an overhanging tree branch which I attach the lead to, to the second swim along the bank and footpath. Only 63metres, but try working out 63m in wraps
I have actually seen somebody put their distance sticks on the bank in this swim, and a cyclist fell over them as he avoided a car and a dog and dog walker coming into the car park through the gates.
There are some swims that you can't walk the line out, you are 'stuck' in a dug out, but it's still easy to mark the line with power gum or insulation tape after casting to a marker.
I have often said I don't think that a quick check with a marker puts the carp off. The number of fish I have caught by being sure I am in the zone, and retrieving the marker after aiming at it. In fact I have had numerous fish within minutes on various waters, from Weybread, Taverham, Brackens and Earith.