My Dad had a system on his boat that allowed a quick release of the dinghy in the case of a crew overboard -- the painter was brought in through a rope clutch and there was a line tied between the clutch handle and the stern pulpit such that a quick push on the line would open the clutch and release the dinghy. It was actually just a bit more complicated, in that he had a short piece of line in the clutch that terminated with a snap-hook which would clip into an eye on the end of the painter -- so you didn't have to feed the painter through the clutch every time after using the dinghy...