The way we used to do it ‘up our way’ was to feed about 50 grains of hemp via a pot and flick over 5 to 10 grains every twentry mins whilst you fish out your inside line. Drop a caster in over the hemp and away you go.
If you want really ‘proper’ roach stret peg the middle of the cut. Keep throwing five or ten casters down the track every ten minutes and after a couple of hours lay a bulked rig in six to 18 inches over depth (depending on flow). Bulk just off borrom, two 10s on the deck. Don’t be afraid to use a float up to 0.75g for this. Hold the rig steady and the float will just sail away if it’s a proper bite. Ignore any little dips. Don’t even think of doing this if you are getting a boat every 10mins. Needs a good 30 mins to settle the line after each boat.
Soft 5s elstic and 0.1 bottom to an 18 kamasan B511 was the way to go. Avoid double caster because holding the rig back makes them spin up!
Give it a go and have fun!