A few downsides to the attraction:
1) Manual pumping, like you said, might be exhausting to children and the elderly.
2) The streams appeared to be rather tiny.
3) No points system, making the target practice somewhat redundant.
I completly agree and, if you watch the video again, you will see the little boy never cranking his own, but rather dad doing it for him.
Going along with that, you get a real workout to get that stream going! Some of the targets are too far away so you can't get a good pressue to get the targets to go. They could have not been working too.
After going around a couple of times, people decided to just start going after other boats and people on the land. It was much more fun that way.
But even with all of that, its alot of fun and the thing is built like a tank. It looks like it can take some beatings from guests so I doubt this ride will be down too often!
While i go to SFGAM often, I dont like getting wet so likely wont ride this, I do hope it serves a purpose by having a LONG line so other lines are shorter.A interactive dark ride would have been a much better addition to the park!!!