RedactedNarrative: Vessel #1 was moored with 2 people on board.  He heard a loud noise of an engine being throttled up when he looked he saw vessel #2.  Vessel #2 spun fast clockwise when the port quarter punctured the starboard side of vessel #1.  Vessel #2 port quarter had a swim platform made contact with vessel #1 along the starboard side several times.  No injuries property damage to vessel #1.