Hi Matthew,
A skyliner is someone who stands behind you when you are fishing and casts a shaddow across your swim probably spooking the fish you are after.
Another way of scaring fish, especially in a small clear river is to wear bright or light coloured clothing. Against a dark green backdrop of trees, you show up very easily - spooking the fish.
All anglers should wear dull drab, even camo cloths. These new "real tree" caomos reall look the business.
I fish a park lake on the edge of a golf course where they have to wear red jumpers and its a well know fact locally that the carp dont feed unless the jumpers are about !!!
Mathew, its all about watercraft. Fish can make out movement above the water line and especially figures on top of the bank against the sky-hence Rons 'skyliner' term.
Dont think cos you cant see fish in murky water then they also cant see you. keeping low and movement to a minimum is something to practice. I am not so sure on the bright clothes issue as who knows how fish see things, but I always go for green/camouflage clothes-its all about confidence.