Hmmmm - that looks more like a running clove hitch (aka a Chinese hitch). It releases very quickly when the 'rip cord' as you call it is pulled. It's a popular mooring knot, since it holds well and releases easily, even when the rope is soaking wet. And even nicer, you can make it as tight as you want, because it will still unravel with a light tug on the rip cord.