How a surfing heat works

1. A small group of surfers, usually two to four, share the waves in a heat for a set time.
2. Five judges mark each ride out of 10, for difficulty, manoeuvres, speed, power and flow. The highest and lowest marks are dropped and the other three averaged.
3. Each surfer may ride many waves, but only their two best wave scores count, for a heat total out of 20. The highest total wins the heat.
4. The surfer with priority may choose any wave, and nobody may get in their way. Getting in the way is interference, and costs part of the heat total.

How long

A heat lasts between 15 and 45 minutes.