RedactedNarrative: Operator stated that a weather front had moved in the area and he was moving a borrowed friends motorboat to a dock in a protected bay on Antigo Island of Pelican Lake.  Operator stated he stopped to wash his hands off in the lake water after cleaning a walleye caught earlier and described the weather as being very dark, overcast, with the wind increasing and that it had been raining at the time he was operating the boat.  Operator stated he had difficulty in judging how far away from shore he was and in retrospect he estimated he was at least 100 to 150 feet away from shore.  Operator estimated the speed of the boat at 20 plus MPH.  Operator operated the boat into the shoreline of Antigo Island and the starboard bow struck a large boulder and the port bow struck a tree.  Operator struck his head on the boats side console/helm and received a concussion, broken nose and contusions as a result of the grounding.