I assume they're a lot more stringent with weapon rules, since these vehicles have obvious weak points.
I looked at the rules; the only weapons allowed are BB guns, up to 150 psi, and not elevated above the horizontal. There are also rules about how strong the boat's hull can be, so you can't make it unsinkable.
It looks fun though, if you don't try to compare it to Battlebots or Robot Wars. They're really not the same at all.