When you lift the tiller arm, the pin bears against the end of the hook, the hook flexes, releasing the tiller arm, but not rotating the cam.
When you come in to the beach, the force of the bottom pushes the tip of the rudder aft, forcing the pin into the corner of the hook, releasing the tiller arm AND rotating the cam to the unlocked position.
HUH? You've just reworded my earlier post #190696. Up cam force bad....forward cam thrust good. In my case there was no slop so lifting or releasing the tiller arm didn't rotate the (chinzy plastic gusseted) cam...it just broke it off at the hook. One thing for certain, shearing a $15 plastic cam is clearly preferable to fracturing a $250 rudder. Either one will sit you on the beach though.