I would suggest that a clove hitch is the way to go on a pilling or bollard. A clove hitch prevents the
line from sliding back and forth around the piling and chafing through. As noted a clove hitch can slip so I back it up with a couple half hitches that keep it from slipping. Double half hitches without the clove hitch can get locked so tightly that it can't get untied.
Jeff