I usually tie a second "locking" hitch at the end of the knot Carl posted, if I'm going to leave the boat for any length of time.
24-SSL (2012) Express w/6 strakes, awesome cable steering because I'm cheap, big gouge in pontoon where marina staff sideswiped their dumpster, redneck emergency toilet via bucket with a toilet seat glued to it (hey, its just a toilet), polished toons and a broken ladder strap. Hoping to log my 200th trip out this year (2018).
150 HP (2013) Mercury Fourstroke with 15x15P SS Enertia (Thanks Todd!) - 41 MPH at 5800 RPM, light load. 39 MPH at 5700 RPM, heavy load. Love this motor.
115 HP (2012) Mercury 4 Stroke with Black Max 13-3/4 x 15P. - 35 MPH at 6400 RPM with light load, but ~15 mph in turns when tubing with a loaded boat. Hated this motor.