Ship traffic has resumed in the Suez Canal following the refloating of a stuck mega vessel.
The Suez Canal Authority (SCA) announced the 20,000 TEU Evergreen-operated Ever Given container ship has been successfully refloated on 29 March, six days after getting stuck.
Captain Don Cockrill, maritime pilotage consultant, has stressed the Suez Canal width is a key factor in the Ever Given getting stuck. “At its surface the canal is about 313 m wide, however its construction profile means that the sloping sides give a width of about 225m at 11 metres draft, decreasing to about 121 m bottom width. Thus at 400m such ships are significantly longer than the navigable width of the canal waterway,” he pointed out.
Slow speed required
The usual transit speed for a ship in the canal is about 8 knots. Cockrill added that “relatively slow speeds are required combined with maintaining a central track within the canal cross-section in order to minimise and maintain a balance of the hydrodynamic forces acting on the sides and bottom of the hull”.
Wind and tidal currents must also be considered, said Cockrill. “The estimated lateral surface area of a loaded ULCC such as Ever Given is about 16,000sqm. A 30-kt. wind such as that which has been reported at the time of the grounding if on the beam will generate a force on the ship side of about 300 mt. Additionally, there is the tidal current to consider. Even a low current of 0.5 knot will impart a force on a ULCC at a similar draft of 75mt.
“Acting in unison, a combined external lateral force on the vessel of about 375 tons (possibly more) is conceivable under the worst conditions. “
The vessel will be moved to the Great Bitter Lake in the Canal for inspection, to determine whether it can resume its scheduled service explained Evergreen.
By Rebecca Jeffrey
