Hey AA! I have seen rocks the size of a baseball, bust through the grate, into the pump and out the side of the bowl, pretty scary stuff, the Idea is to keep the boat on a high step plane at all times, a lot of these boats are tunnel hulls and can run in less than 3" of water (sucks the moss right off the rocks).
One word... Balls
Typically the air time is from hitting a depression from a submerged rock (more acurately a boulder) sometimes you don't see them, the boat takes off like a rocket, and you get a suprise in your driving suit, I wish my buddies and I could still race, but kids, mortgage, job, changes everything.
These guys are a rare breed.
