Ok. It seems like there is a lot of misinformation or guessing on the how a ride really works (as usual). I'll try and correct some of the misconceptions. First of all, ride computers do not reboot, they are not that kind of computers. There are 2 ride control computers for EVERY ride, one is the Control computer and the other one is the Monitor computer.
Here is the basic scenario for most water rides like Splash, POTC, Kali, Maelstrom (Small World and Gran Fiesta are just basic because it no lifts or drops).
The Splash Control Tower CM is watching the whole ride through the camera monitors. That is their job to make sure everyone is safe and sitting down and not doing anything they shouldn't be doing. So if they see someone standing up, they hit the RIDE STOP button, that stops the lifts and raises the boat stops. Usually they make a PA announcement to that zone and if that person sits down and everything else is good to go, then the CM raises the RIDE STOP button and pushes the reset button and then everything carries on normally.
But what happens sometimes when a log stops and it just happens to be on the edge of sensor and may not blocking it all the way or could be a disagreement, then the ride won't reset if detects a problem. So the tower calls maintenance to look at it to see if it is a sensor failure or just out of position. It used to be easy to fix, all they had to do was switch to maintenance mode and jog the log to the proper position and switch back to normal. BUT now because they worry so much about the LEGAL stuff and somebody suing them from jogging the boat another 6 inches, maintenance is allowed to move the boat in maintenance mode. So what happens is they have to evacuate all the logs, so the first thing they have to do is shut down the water. Once the water is shut down, then all the Operations CM's can RAC(Remote Access Control) out basically by putting an lock on the E-Stop so nobody can start the ride with CM's in the ride. So now they can evacuate each and every log(this is what takes the longest time) and when the guests are clear of the ride, then maintenance can jog that boat 6 inches, then they can start the ride back up, start the water back up and re-enter the boat counts in each zone.
So like I have said before, most of ride downtimes are guest induced, sometimes CM induced, but rarely ever a ride just breaks down, maybe 1% of the time.