RedactedNarrative: Vessel #1 was anchored with an insufficient anchor and line to hold the vessel.  The waves caused vessel #1 to drift into a cement wall.  Occupant #1 notice vessel #1 was striking the cement wall and attempted to move the vessel while standing on a cement wall to minimize damage.  Vessel #1 struck occupant #1's right knee, temporarily pinning it against the wall.  Occupant #1 was transported to the hospital.  The Operator stated that 7:00 p.m. on July 17th, 2016 he anchored his boat approximately 50 yards from the shoreline with a 20lb mushroom anchor and an undetermined amount of line but state it was not seven times the depth of the lake.  At 10:00 p. m.  the same date, the Operator noticed the boat had moved about 100 yards from where it was originally anchored.  He decided to pull up the anchor and he beached the boat bow first into the sandy shore between two cement walls and held the anchor down (anchor and line still attached to bow eye of boat) with two large rocks.  When he woke up at 8:00 a. m. he noticed that the line attached to the boat and anchor had snapped and the boat was being thrust again the cement wall and was filled with water.  The Operator attempted to push the boat away from the wall when his right leg became pinned between the port bow of the boat and the wall.  Due to the extent of pain and possibility of injury, the operator called 911 and was transported to University Hospital in Geneva where he sustained a knee contusion and other possible injuries (see EMS report for further).  On 7/19/2016 at 10:00 p.m. I made contact with the operator and he stated at 9:00 a. m. on 7/20/16 Tim's towing was going to retrieve the boat from the shoreline and scrap it for $350.00.  The vessel was confirmed towed from incident location on 7/20/16. 