RedactedNarrative: Vessel 1 was backing into its slip when the port starboard side of the A frame and tackle affixed to the aft cockpit of V1 struck and collided with the starboards bow rail and rub of V2 docked in the adjacent slip. This collision broke off the stanchion affixing the bow rail to the gunwale and bent the top of the bow rail. Operator inexperience attributed to the collision.