RedactedNarrative: Operator of V1 was attempting to dock his vessel in a slip at Dam Site Marina and in the course of docking he put V1 into reverse and then shifted the throttle lever back into the forward position; however V1 did not shift and continued in reverse. V1 collided with V2 which was docked in a slip across from V1's slip.  The operator notified the marina of the collision and left his contact information. Upon inspection V2 had a gaping hole approximately 3" in diameter on the stern. V1 sustained only minor scratching on the swim deck; however the throttle cable was found to have snapped.