I recently got involved in canoe racing and I am curious about the most efficient techniques of turning a canoe around a buoy without losing your forward speed.
If the turn is a sharp turn around a buoy the trick is to pivot. Depending on how fast you are going, the prow needs to be a bit past the marker. Then pivot around it first with a bow pull and then a cross body pull at the stern.
For example: if you are going around a buoy to the starboard and have your paddle on the starboard side too, as you pass the marker start with a pull straight at the gunnels as far to the bow as you can (while still retaining good form). Then as the stern swings, switch to a cross body pull as far to the stern as possible.
I think a cross body pull to the stern is more powerful than a pry even if you feel a bit like a pretzel doing it.