The closest thing I’ve ever done to Kayak Fu would be boatball, which I think I’ve discussed here.
It involves a water polo ball, a couple of floats for goals, and a lot of people with whitewater kayaks who would rather be on a river with a gradient, but alas, we live in Memphis, and the rivers here don’t ‘do’ rapids. We put a lot of long miles on our vehicles, to get to the whitewater from Memphis… but you make your own whitewater in boatball.
Boatball is a sort of sandlot version of kayak polo, I think. We had a kayak polo team visit one day and bring actual goals and things and they knew rules and had skills. It was all very exciting but it was like the neighborhood kids playing rough-house style football being visited by the local pro team. Just not the same game.
One of the few rules we have is “when hands go in for the ball, paddles come out.” So I don’t think anyone has lost digits over the years. Good rule.
One of the non-rules is “don’t grab anybody’s loops” You don’t have to have that rule, you just have to know that if you just have to grab another person’s boat and haul back on the grab-loop, your hand is fair game, depending on the disposition of the other player and the speed of his paddle blade.