Just for fun (2)

A paddler is swept down to Gate 2 before negotiating Gate 1 and turns back, too late to avoid his/her head passing through the gate line.

The paddler goes back to upstream Gate 1 and negotiates it, but in doing so touches the left pole with the tip of the paddle. He/she then does Gate 2 correctly.

What (if any) is the penalty on each gate? Why?

Gate 1: 50 Crossing the Gate 2 gate line "kills" all preceding gates, so a 50 on Gate 1 (which cannot be cleared) has been incurred before the paddler even gets to it. The touch doesn't matter, because 50 is the maximum penalty on a gate.
Gate 2: 0 Coming back through the gate line could have incurred a 50 penalty, but because the paddler's first and last passages through Gate 2 were both in the right direction there is no penalty.

Just for fun (1)

Downstream Gates 2 and 3 are set quite close together.

Approaching Gate 2, a paddler capsizes and is carried though both gates upside-down. The upturned hull touches the tip of one of the poles of Gate 3 as it passes through.

The paddler then rolls up, paddles back and does both gates correctly.

What (if any) is the penalty on each gate? Why?

Gate 2: 50 Negotiating the gate capsized incurs a 50 penalty. The paddler cannot clear the penalty by renegotiating the gate because he/she has already passed through Gate 3, and Gate 2 is "dead".
Gate 3: 2 Negotiating the gate capsized incurs a 50 penalty. The second passage through gate 3 clears the 50 penalty for the capsized passage, but the touch penalty on the first (capsized) passage stands.