RedactedNarrative: On 8/30/14 at 15:30 hours in the area of Callville Bay flat wake zone at Lake Mead National Recreation Area, a house boat and a motor boat attempted to dock with each other. The weather conditions at the time were wind speeds of 7-14 mph with 6"-2'' choppy water. Vessel #1 was reversing its stern to the bow of vessel #2. The operator of vessel #1 turned off the engine when vessel #1 was about an arms length distance from vessel #2. Vessel #2 was not in operation.  At that time passenger of vessel #1 attempted to grab hold of the deck of vessel #2 while standing on the swim platform. Due to the choppy water vessel #1 moved in a downward motion while vessel #2 moved in an upward motion. This action caused victim to slip off the swim platform between the vessels. victim has both of his legs struck by vessel #2 causing a fracture of the lower left leg and deep lacerations to the right leg. victim was removed from the water and transported to the gas dock for EMS treatment.