Ports want to ensure safe and reliable loading operations for all ships. Increase in ship sizes, especially
container ships, potentially cause unsafe mooring situations. For ships moored at quay walls, there is also a
lack of international guidelines for mooring arrangements. This paper presents a case study for a moored
containership being passed by a vessel of identical dimensions. The behaviour of the moored ship is simulated
using UGent’s time-domain mooring software Vlugmoor. Starting from a well-balanced arrangement used in
daily operation, three optimisation steps are presented, aiming at lowering the ship motions, which are critical.
The first step explores the impact of changing line positioning to reduce line length disparity and improve
efficiency in critical force directions. The second step considers a lower fore mooring deck to reduce line
steepness, as well as additional winches below the bridge and funnel. The third step proposes replacing medium
stiff lines with a very stiff HMPE line, combined with an elastic tail. The effect of these optimisation steps on
the ship motions are presented and compared with predictions based on efficiency parameters, expressing the
capacity of the configuration to deal with positive and negative surge forces. It is shown that applying these
optimisation steps can significantly improve the safety of a moored container ship during a ship passage
