The towing operation of multi-tug-assisted ship navigation mainly relies on the experience of the captain, and there is no set of effective operation methods. Therefore, it is difficult to achieve accurate assisted navigation when multiple tugboats work in coordination. The calculation method of maneuverability of the towing system with multi-tug-assisted navigation is proposed in this paper. In view of the complexity of multi-tug-assisted large ship maneuvering, this article focuses on solving the problems of force analysis and maneuvering modeling between the multi-tug and ship systems. Firstly, a maneuvering mathematic model for towing ships is established, and the hydrodynamic force of the hull, rope force of the tugs, and force of wind interference are analyzed. The thrust and moment of the ducted azimuthal propeller are calculated, and the mathematical model of the tug’s cable tension is discussed. Then, the fourth-order Runge–Kutta method is used to solve the differential equations of the maneuvering motion of the ships and each tug. Based on the ship-towing process by multiple tugs, a multi-tug-assisted ship towing simulation platform was built by using the Visual Studio development tool. Finally, on the simulation platform, multi-tug longitudinal-towing-simulation experiments at different speeds were carried out, and the simulation of turning towing maneuvers under the influence of wind was done. The simulation results showed that as the towing speed increases, the initial towing speed fluctuates greatly. There is a significant drift effect on the ships by the wind force. And the wind will cause a fluctuation in the tug’s rope force. The simulation of the multi-tugs towing a ship entering the port was carried out in the port environment. The results showed that the multi-tug towing system and simulation platform may be used for the safety training of the tug’s crew.

In the process of oil exploitation, subseatrees sometimes vibrate. In this paper, fluid–structure coupling software was used to study the causes of subsea tree vibration. First, the complex subsea tree model was simplified, and ageometric grid model was established for software calculation. Then, under the given two working conditions, the software Fluent was used to analyze the pressure and velocity distribution of the subsea tree pipeline’s flow field. It was found that the pressure of the flow field changed greatly at the variable diameter and right-angles. Using Ansys Workbench software, flow-structure coupling calculations and modal analysis of the subsea tree were carried out. The results showed that the vibration of the long straight pipeline section was severe. Finally, the paper puts forward the measures to reduce the vibration of subsea tree pipelines and provides construction advice for the safe production of subsea trees.