Here's a great knot for you to use on the next boat you buy from Hampton Yacht Group. Originally known as the "highwayman hitch", this knot is useful when one is about to leave the dock, or when tied up for a very brief period of time. You'd replace the standard cleat knot with the highwayman hitch, get on board and when everything is set, you just pull tag end of the line(s) and you're free of the dock.
This knot shouldn't come undone when it is well-dressed, pre-tensioned and used with rope with a good degree of friction (such as hemp, sisal or soft nylon) but if you want to be totally sure it won't capsize and slip, you could inset a small bit of wood or metal in the loop of the quick-release part, draw it snug and take it out when you're finished.
