Aktis Hydraulics completed an investigation into three independent events of historic mooring line failure events where long swells arrived at an LNG terminal, diffracted around a detached breakwater and impacted the mooring integrity of the carrier.

Aktis’ role was to reconstruct the wave conditions at the time of each of the three events and to assess the wave diffraction behaviour around the detached breakwater and to evalaute the consequences at the location of the moored ship resulting in large resonance behaviour of the carrier at the terminal and eventaully leading to the lines failing.

The wave propagation has been done using by coupling subsequently the numerical models including (from off- to near-shore):

WW3 » SWAN » SWASH

The signals from SWASH were decomposed into phase related systems diffracting around the breakwater heads and the fluid column velocities as well as the wave directional amplitudes have been assessed to accurately describe the cross sea behind the detached breakwater.

For evaluation of the hydrodyanmic loads on the LNG Carriers use was made of ANSYS-AQWA.