Kick up rudder cleat

It's a nightmare on the lake right now, the drought has meant water levels are unseasonally low, tonight I broke the rope holding the rudder down, now I seem to recall a cleat that might under extreme duress come open rather than have what happened tonight and the rope snap.

Is there such a device?

There is, I have one, came fitted by Milanes, not convinced how well it would work, meant to adjustable for break out tension but cannot confirm efficacy. 

Works reasonably well to be honest. Obviously when new stiffer than when used a bit. It isn't going to prevent slight damage to the leading edge of the blade but it will stop the transom being ripped off. Worth getting one, not sure why they aren't standard to be honest

Some do, locked by a spring loaded mechanism in the tiller/stock. Lift the tiller and the lock disengages, any hard thump on the rudder blade should be enough to pop the locking mechanism. The one on my Spice broke and I modified it, it still works much the same but I can't really comment on how effective it is in protecting against accidental grounding as I haven't yet tested it in extremis.

Thanks DavidYot, duly ordered, it screwed my race last night, got water called on the start line and forced over, so had to dip the line, then proceed to thump the wreck and about every sand spit on the lake chasing the increasingly Jammy Jack in the other Solution and just as I reeled him in the rope snapped it took me a couple of minutes and a leg of weather helm to think about tightening the screw on the downwind leg. I never did get him..