Validation of a Numerical Model of a Ship and Cable-Towed Body System
Conference
International Maritime Conference 2025
Title
Validation of a Numerical Model of a Ship and Cable-Towed Body System
Abstract
Underwater cable-towed systems are critical for naval operations (including resource exploration, search and rescue, underwater archaeology and military applications), yet their dynamic behaviour under varying sea states and manoeuvres remains challenging to predict. To address this, the Defence Science and Technology Group (DSTG) have developed a high-fidelity simulation capability using the Fredyn software package to model the coupled dynamics of ships, cables, and towed bodies. This study presents an overview of recent numerical simulation validation activities performed by DSTG using both controlled modelscale experiments and full-scale sea trials. The simulation model solves ordinary differential equations which account for the balance of forces and moments associated with ship and body motion, the cable weight in water, hydrodynamic drag of the cable, as well as solving for cable bending and elongation. The simulations predict the ship and body motion, cable’s shape, tension in the cable and ship towing loads. The approach retains the full two-way hydrodynamic and mechanical interaction between the towing vessel and the cable-towed body system, hence the impact that the cable-towed body arrangement has on the manoeuvring and seakeeping characteristics of the ship is accounted for. Experimental measurements of cable shape and tension from the literature were compared with simulation results for a variety of different configurations, demonstrating reasonable agreement across the examined conditions. These findings confirm the model’s fitness-for-purpose and will improve the reliability of the operational decision support systems currently under development that will be the focus of future work.
Key takeaways:
- The research team focused on improving simulations that help predict how ships and underwater equipment behave when cables are used for underwater towing, a process important for activities like search and rescue, underwater exploration, and defence missions.
- The paper provides multiple validation cases and a variety of operation modes for the experimental validation including tank scale and sea scale, steady state and dynamic rigid body motion, which demonstrates the robustness of the model and real world defence focussed applicability.
Authors
Martin Leahy PhD BSc(Hons), Senior Modelling and Simulation Engineer, Shoal Group
Sean Logan, Defence Science Technology Group
Daniel Sgarioto, Defence Science Technology Group
Samuel Smith, Defence Science Technology Group
Blake Burgess, Defence Science Technology Group
Date
Thursday 6 November 2025
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About Shoal
Shoal is complex systems design company. We use Systems Engineering combined with Modelling, Simulation and Analysis to help our clients define, analyse, decide, optimise, and deliver technology-intensive projects in complex environments across Defence, Space, Transport, Energy and Infrastructure.
More: shoalgroup.com
Contact
Matthew Wylie
Chief Engineer, Shoal Group
[email protected]
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