Masochistic. Mellow for the first 1.5km, then suddenly drops steeply through quarry workings. Watch out for the river disappearing underground: carry up river right past the quarry buildings to where it re-surfaces. This happens again later. Once you reach the footbridge (an alternative putin) you've braved the worst, and the river eases to grade 4.
Putin at Delford Bridge, the bridge downstream of the village of Bradford. Takeout at the bridge at Tregaddick just upstream of the confluence with the river Camel.
Rainchasers is best experienced as an app.