On June 28, 2006, about 0335 Pacific daylight time, a Cessna 170B, N2924D, veered off the side of the runway and ground looped at Nut Tree Airport, Vacaville, California. Monterey Bay Aviation, Inc., was operating the airplane under the provisions of 14 CFR Part 91. The renter commercial pilot and two passengers were not injured, and one passenger sustained minor injuries; the airplane sustained substantial damage. The cross-country personal flight was departing with a planned destination of Watsonville Municipal Airport, Watsonville, California. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot submitted a written report. He flew 2.7 hours from Watsonville to Little River for fuel and then to Ukiah where he and his family ate dinner and spent the night. On the day of the accident they departed Ukiah at 0800, stopped at Shelter Cove at 0900, and then flew to Brookings, Oregon, for fuel. They flew to North Bend where they refueled and added oil to the airplane, ate lunch, and shopped. At 1400, they departed North Bend, flew up the mouth of the Columbia River Gorge, and landed at Astoria for fuel and coffee. They departed Astoria and flew to Myrtle Creek, arriving there at about 2015. The pilot's family exited the airplane, and he performed three full-stop solo landings for night currency. The family boarded and the flight proceeded to Crescent City, California, where the airplane was refueled. The flight departed Crescent City airport with full fuel and the pilot navigated by pilotage to the Nut Tree airport. The Automated Surface Observing System (ASOS) for Vacaville reported the winds to be calm, and the pilot landed the airplane on runway 20 without incident. He decided to refuel the airplane at idle power, because he had experienced difficulty in starting the engine in Crescent City. The pilot then taxied to runway 2 for takeoff. He raised the tail of the airplane at a lower airspeed than normal. The airplane yawed to the left and the pilot immediately applied full right rudder. The airplane veered off the left side of the runway and bounced hard on a dirt berm. It spun around 180 degrees before coming to rest beside the runway. After exiting the airplane, the pilot noticed a steady 1- to 2-knot wind from 200 degrees. The pilot stated that the airplane and engine had no mechanical failures or malfunctions during the flight. The wind conditions at Vacaville, at 0353, were reported to be from 200 degrees at 5 knots. The pilot flew a total of 17.4 hours in 2 days with little sleep. When he signed out the airplane, the Hobbs read 34.3. The airport manager reported the Hobbs and tachometer at the time of the accident to be 51.7 and 2823.3, respectively.