Sailing injuries on cats that I have witnessed have been mostly during pitch poles. Prindle 19 a crew mate flew out on the wire on a pitch pole and came back to the boat hiting the mast and it broke his neck. He hit the mast hard enough to capsize us and knock the mast off its base. Other pitch poles that resulted injury where bad bruises whenever the person was unluckly enough to hit a part of the boat. I also know that if a crew mate releases the trap wire too early while tension is still on the shock cord, the ring can catch you in the eye resulting in a lot of stitches. Another incident is breaking a trap wire and then being dragged by the main sheet wrapped around your leg. That leaves a good mark too. Of course, this needs balance with the 25 years of going out and nothing happening.