SINKERS on a fly line----> It's called CHUCK an DUCK. The old salmon an steelhead guy use to do it all the time, killer way to pull'em off the bottom in N.Y.
FLYFISHING HOLES, It's not hard to do, you will need practice . TIMING will be the most important thing, know your SINK RATE an get the timing down. use the boat to your advantage nice slow controlled drifts over the hole, ones you get a fish REMEMBER EVERYTHING you did an REPEAT it no magic just get out an SPEND some time ON THE WATER.
if you fishing a HOLE W/ fly rod an just drifting. your NOT casting,your letting your line OUT before the hole, an letting the fly DRIFT IN an SINK W/ the current in the hole, as I said PRACTICE.
GOOD LUCK GOOD FISHIN