RedactedNarrative: Victim was rowing his dory into granite rapids when a lateral wave flipped the boat.  Victim was thrown into the water and flushed through the rapid.  During the swim, victim came in contact with a rock wall and hit his head.  He also received abrasions on his leg and hand.  From this moment the victim had no recollection of the incident until a rescue boat arrived to assist him.  Victim appeared disoriented and did not know how or why he was there it was determined that victim had suffered a concussion and was evacuated to the south rim clinic by nps helicopter.  Guardian helicopter then transferred him to fmc for further evaluation. He was diagnosed with a minor concussion and released that evening to his wife.