The 90-degree rotation of the blade around its own axis so it travels flat over the water between strokes instead of edge-on. Order: extract, feather, hands away.
The order is fixed and still gets muddled constantly: first the extraction — hands drop, the blade comes vertically out of the water — then the feather, then hands away. The blade must be fully feathered before your hands leave your body; feather too late and you begin the recovery with a blade standing on edge, catching every gust and every wave. The rotation comes from rolling the fingers, not from yanking the wrist, otherwise it turns jerky instead of fluid. In sculling this becomes the hardest timing job in the sport, because both wrists have to roll at exactly the same moment: if one blade turns early you lose precisely the stability two symmetric blades are supposed to give you. Practise it at a low rate — at speed you hide synchronisation errors rather than fixing them.