Someone was asking how Kali River Rapids compare length wise to the average Six Flags rapids ride. Using videos, not counting the lift at the start, you're looking at 2:35 for Kali. One interesting thing is that the river rapids ride was invented by Six Flags. The general manager of one of their park came up with the idea and then partnered with Intamin (making of Kali River Rapids) to develop it. That was back in 1980.
Looking at other examples, not counting their lifts. All those rides are Intamin rapids rides using the same 12 seaters boats that Kali have.
Six Flags Magic Mountain "Roaring Rapids": 2:40. What is crazy here is that we're talking a bare bone ride! It was the third one to ever open and it doesn't even have any waterfalls or water jets, etc. Just amazing rapids and waves and some rock work at the end and forest as scenery the rest of the time.
Six Flags Over Texas "Roaring Rapids": 2:40 again. There is a whirlpool section and several massive waves. Rockwork and forest as scenery.
Six Flags Over Georgia "Thunder River": 3:35 . Very impressive ride with amazing waves, two tunnels and a great waterfall. The endinvolve a fast tunnel, crazy wave 1 (think bottom of drop at Kali), crazy wave 2 and then the boat end up under a waterfall!
Six Flags St Louis "Thunder River": 3:25. Not as exciting as Georgia's rapids, but long and varied.
Six Flags Great Adventure "Congo Rapids": 3:05. Second rapids ride to open and now the oldest since the original was demolished along with the rest of Six Flags in Houston. Great waves, but sadly, the waterfalls at the end have been broken for a while.
So, Kali River Rapids is among the shortest rapids ride out there. Plus, what doesn't help it is that the ride itself is just no good beside the drop. There is maybe one good wave after the drop and the waterfall at the start barely get you wet. The water effects at the end help a bit, but it is not much. They could improve it by adding a rapid section to those dead zones and a waterfall that actually get you wet later.
How are rapids created on those rides? Pipes of various sizes are bolted to the bottom of the channel. As the water pass over them, they create white water that will get you wet.