The mooring of ships to harbors, terminals, and offshore structures is a common and essential procedure in most seafaring operations. Inadequate mooring can result in significant structural damage to the berthing vessel and moorings. To this day, most mooring operations are still performed in the same manner as they were decades ago; they are dependent on heuristics, or in other words, the captain or mooring master's experience. Unfortunately, the effects of global warming and climate change are altering the hydrodynamics of the sea, making manual mooring operations a very risky venture.
The challenge: To design a mechanism to control and automate a mooring system between two ships at sea.
MapleSim™ and Maple™ are used to:
- Create a physical model of the two ships and mooring cables
- Develop a realistic model of the external environmental forces and use the results to simulate conditions at sea
- Design and tune an appropriate controller to stabilize the system
Developing a realistic model of the external forces was critical to the design of the controller. This allowed the engineer to tune the controller, eliminate vibrations, and stabilize the tension in the line. With the initial control system complete, further improvements can be made to the disturbance model by including irregular waves from multiple directions, wind gusts, wave drift forces, and the interaction effects from passing ships.