Long-term modelling of moored ship motions and loads

This project calculated dynamic moored ship motions and loads over a 5-year hindcast period.

Principal investigator

Tim Gourlay tim@perthhydro.com
Magnifying glass

Area of science

Ship Hydrodynamics

Systems used


Applications used

Partner Institution: Perth Hydro| Project Code: director2104

The Challenge

Western Australia is exposed to oceanic long-period waves (swell) which penetrate in to coastal areas and ports, often creating unacceptably high
motions and loads on moored ships.

Due to the computational intensity, moored ship calculations are typically done using several carefully-chosen sets of environmental conditions. This
project aimed to extend the method to calculate long-term motions and loads over a multi-year period, to assess long-term mooring operability and safety.

Environmental inputs included hindcast wind, current and wave data at hourly intervals over a 5-year period. Wave data included full directional wave

The Solution

The existing code MoorMotions (www.moormotions.com) is written in MATLAB. It was easily converted to OCTAVE to run at the Pawsey supercomputing centre. Nonlinear time-domain simulations were run for 43,824 sets of input wind, wave and current conditions (hourly data over a 5-year period).

The Outcome

Calculations totalling 10,000 core-hours, that would be unfeasible in the past, were achieved in under a week on the ZEUS cluster at Pawsey. Results were used to assess long-term operability of a dynamic mooring concept design.

Figure 1: General ship mooring