Wave
Double up
When the energy of two waves combines into one larger wave, sometimes used off a turn-around to add power for a hit.
A double up occurs when the power of two waves combines, stacking their energy into a single, larger, more powerful wave. In towed sports a double up is sometimes created intentionally by turning the boat so its wake crosses its own previous wake, producing a bigger ramp for a trick. There is even a hand signal (forefinger and thumb forming an L pointed left or right) to call for a double-up turn.
The combined wave packs more punch but is also less predictable, so double ups are used by more advanced riders chasing extra air.