On May 17, 2003, at 1730 central daylight time, a Piper PA-11, N4711U, piloted by a commercial pilot, sustained substantial damage when it struck a tree while departing Lac Du Flambeau Lake, located near Minocqua, Wisconsin. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being operated under the provisions of 14 CFR Part 91 without a flight plan. The pilot and his passenger reported no injuries. According to the pilot's written statement, he had landed on Lac Du Flambeau Lake to refuel, however no fuel was available. The pilot noted the airplane had approximately 8 gallons of fuel remaining and he decided to depart the lake. According to the pilot, while attempting to takeoff, the airplane "failed to climb out of lake at end of cove." The pilot stated he "reduced power and turned to land in a bog/swamp." During the landing approach the left wing strut impacted a tree and the airplane landed hard on the floats. The pilot reported substantial damage to the left wing, a lower fuselage longeron, both wing struts, and both floats. The pilot reported a total flight time of 2,518 hours, of which 1,011 hours were in single-engine airplanes and 1,507 hours were in multiengine airplanes. The pilot reported flying 90 hours within the last 90 days and 41 hours within the last 30 days. The pilot reported he had flown 5 hours in the same make and model as the accident aircraft, all of which were flown within 24 hours of the accident. The pilot reported there were no mechanical malfunctions or failures during the accident flight.