What counts as going through a gate correctly?

• The order: "All the gates must be negotiated in numerical order."
• The gate line: the line between the bottom ends of the two poles, carried straight down to the riverbed.
• The head: "The whole head of the athlete or athletes must cross the gate line" from the correct side.
• The boat: "Part of the boat must cross the gate line at the same instant as the whole head crosses the line."
• Any way round: a gate may be taken "in any presentation from the correct side".
• When it begins: the attempt at a gate starts when the boat, body or paddle touches a pole. It also starts when part of the head breaks the gate line.
• When it ends: when the paddler starts the next gate or crosses the finish.
• Trying again: repeated attempts without a touch are not penalised, as long as no part of the head has crossed the line in the wrong direction.
• Underneath: passing part of the body or boat under a pole without touching it is not penalised.
• In doubt: each gate judge must give the benefit of any doubt to the athlete.

The glossary has gate negotiation, undercutting and the gate.

A judge on the bank needs something that can be seen from a distance in spray. The head either passed between the poles or it did not. Tying the boat to the same instant stops a paddler from leaning a head through a gate that the boat never reached.