This paper is focused on an investigation into the control dynamics of a boom crane through a study of guided payload pendulum motion with a non-uniformly rotating boom-driven pivot center and variable cable length. A time-optimal control problem was formulated and numerically solved with constraints on the allowable payload swaying value using JModelica.org freeware with Optimica extension. Solutions of the optimum speed problem for the dynamic model describing the movement of the payload from the initial position to the final position are found, taking into account the nonlinearities associated with the Coriolis force, and the change in cable length during the motion. Two cases are considered: with and without taking into account the constricts on the swaying value. It was found that taking into account the constricts on the swaying value leads to an overshoot of the phase variable length. The obtained results can be used for cargo transportation by crane in various fields: industry, construction, etc. The resulting control will allow a reduction in cargo transfer time, which will lead to an increase in labor productivity. It will also reduce the amount of payload swaying, which will reduce the likelihood of injury during loading and unloading operations. The model is nonlinear, and the Coriolis force and other nonlinearities are taken into account. The model is electromechanical; the characteristics of the electric motors of the tower and the winch are taken into account. A comparative analysis of the problem of optimal control with and without allowance for restrictions on the cargo swaying value is provided and differences in the control functions for each of these cases are defined. The optimal control, taking into account the change in rope length, allows the solution of practical tasks in moving the cargo, taking into account the presence of obstacles that arise on the way of the cargo.