I also use the locking device that goes over the screw clamps in addition to a nylon rope tied around the top of the engine. I found out the hard way that a rope attached to the O-ring next to the clamps only saves your engine if the clamps come undone. I backed into a stump last year and cracked the engine right off the bracket into the river. I therefor now ruse a nylon rope tied around the top of the engine for us blind free drifters.