When it's a 50
When it's NOT a 50
There is no part of the boat in the gate when the paddler's head passes through.
Photo stolen from the judging guide produced by Canoe Slalom New Zealand
If a paddler or C2 crew would have incurred a 50 penalty by "no boat" the paddler/crew can return, make a second attempt at the gate and "clear" the 50 provided that they did not pass through the gate line in the wrong direction and they have not touched or negotiated a following gate.
If there was a touch on any pass, the touch penalty stands.