Abstract: At approximately 3:30 p.m. on November 17, 2008, a crane operator was conducting a boat lift at a marina in the Kinnickinnic River in the port of Milwaukee, Wisconsin. The ground on which the crane was set up consisted of a loose stone base and concrete. The left rear outrigger was positioned on loose stone and double-span blocked on wood timbers. The right rear outrigger was blocked on a single set of wood blocks at the edge of the boardwalk. The right front outrigger was set on concrete with wood outrigger blocking stacked and spanned. The left front outrigger blocking was set on concrete with wood blocking double-stacked and spanned. The pieces of wood used for blocking were not uniform. Although the site had been examined before the crane's outriggers were extended into place, the soil under the concrete on which the right rear outrigger was positioned had eroded. The erosion over time created a void in the soil, and as the third boat was lifted, the concrete in this area cracked. The crane then tipped over into the river. The operator rode the crane into the river and managed to escape from the cab before the crane went underwater. He broke out a glass window in the cab and swam free of the crane. He was then pulled from the water by coworkers. The U.S. Coast Guard reported that the operator was taken to the hospital for examination and observation. Injuries were limited to bruises and minor cuts. He was not hospitalized. The injury line says the crane operator received no injuries. During an inspection of the lift site after the accident, a sink hole or erosion point behind the seawall was noticed about 150 feet to the southwest of the lift area. It was also visible from the lift area. This should have initiated further inspection of lift area to quantify the ground capacity and stability conditions. The crane operator indicated that he was not sure if the spreader bar was certified before operation. He also indicated that it was assembled on the site and weighed about 2,500 to 3,000 lbs., but he was not sure of its weight. The erosion of the soil was a primary contributing factor that caused the loading on the crane to transfer to a dynamic load. Once the crane's capacity had been exceeded, the crane tipped over into the river.