Nowadays, with account of depletion of hydrocarbon raw materials onshore there is a tendency to develop deep oil and gas fields. In course of development of the fields, significant amount of various lowering-and-hoisting operations are fulfilled. The task of determination of the forces in load lifting from deep depth in the conditions of random sea state is solved on the basis of statistic testing method (Monte Carlo method). Math-ematical model took into account non-linearities caused by jerking and non-linearities of forces of the load hydrodynamic resistance. Comparison of the results with relevant solutions of linear tasks has been made.