RedactedNarrative: Unit 1 was stopped in the Ashley River with the motor at idle.  Unit 2 attempted to pass Unit 1 on the port at a close distance.  Operator of Unit 2 stated that while attempting to pass Unit 1 he hit a chop that pushed his starboard stern into the port stern of Unit 1.  The collision created a puncture in the port stern of Unit 1 and caused a passenger on Unit 1 to hit his head causing a concussion.  The operator of Unit 2 estimated his speed at 25 mph.