The mooring hitch is a quick release knot used primarily by sailors, but also by lumber jacks and riggers as well. It is a very secure way of tying a line while still being able to release that knot very quickly. When a sailor is single handing or working a boat alone, they don't want to be jumping ashore to tie or untie the boat to a mooring or dock. By securing one end of the line to the boat then simply putting a loop over the mooring post or cleat and then securing the bitter end to a cleat on board. With this hitch they can get free and away in seconds without losing the line or having to waste time or energy going ashore to untie that line, maybe having to make a dangerous leap into an unsecured boat.
The mooring hitch is handy anytime you need a quick release application and could be useful in many survival situations such as:
Take a round turn about the post, cleat, ring or rail that you are securing to.
Make a half-hitch with a bight (just like tying a shoe).
Make another round turn on the standing part and push another bight through the first eye you created.
Pull all of the slack into the second eye until the knot is snug.
To release the knot, just pull on the bitter end and the it will dissolve before your eyes. Even if the knot has tried to bind because of a load that was placed on it, a stout jerk on the bitter end will free it up.