NOTE: re-titled, updated thread. Please refer to the last page for the most recent post.
Such an incident seems unprecedented for a ship this size, and thus this report about it belongs here because it is both historic and a morbid spectacle:
Maritime Traffic Jam Grows Outside Blocked Suez Canal
26 Mar 2021
The Associated Press | By Samy Magdy
SUEZ, Egypt � A maritime traffic jam grew to more than 200 vessels Friday outside the Suez Canal and some vessels began changing course as dredgers worked frantically to free a giant container ship that is stuck sideways in the waterway and disrupting global shipping.
One salvage expert said freeing the cargo ship, the Ever Given, could take up to a week in the best-case scenario and warned of possible structural problems on the vessel as it remains wedged.
(...SNIPPED)
Last edited by Haijun watcher on Sun Apr 11, 2021 5:51 pm, edited 2 times in total.
"Haijun" means "navy" in Mandarin Chinese.
"You have enemies? Good. It means you stood up for something in your life."- Winston Churchill
The situation of the container ship Ever Given, grounded since Wednesday morning at the southern entrance of the Suez Canal, is not improving. A flotilla of eight tugs attempted unsuccessful manoeuvres in the hours following the accident. Experts from Smit and Nippon Salvage were appointed to salvage the 400 metre long, 20,000 TEU vessel.
The container ship was reportedly stranded 15 metres forward on the sandy bank of the Suez Canal. Given its weight, it is very difficult to pull on its hull without risking weakening its structure. Hence the presence of a large number of tugs trying to distribute the towing effort. But this alone was not enough. Hence the arrival on site of two dredgers which, guided by divers, will probably have to dig a trench to clear the bow of the ship. On the shore, excavators were also trying to clear the bow.
Given these circumstances, it would seem that a lightering of the ship is almost inevitable. Deballasting or lightening of the fuel capacity is possible but difficult, again because of the stability and strength of the hull structure. The solution could therefore be to remove a number of boxes on deck. Given the height of the container bays, this will require a very large crane, of which there are relatively few. The rescuers are also relying on the tide, which will increase from next week onwards. In the meantime, hundreds of ships of all types are now waiting in both directions (Europe-Asia and Asia-Europe). The effects on commodity prices are limited for the moment, but the question of passing through the Cape of Good Hope is now being raised for shipowners. Just over 10% of world trade passes through the Suez Canal.
There would be a surge in demand for bunker fuel if they re-route around Africa. Most of the ships waiting only has enough fuel to the Suez route between Europe and Asia.
[quote] A "human error" could be at the origin of the grounding of the container ship, affirmed Saturday (March 27th) the head of the Egyptian Authority of the Suez Canal, at a time when the efforts are multiplied to refloat the ship blocking this seaway, one of the busiest in the world. [/ quote]
It could be a mistake by the canal pilot (s) on board, or by the crew... or both.
The same ship had an earlier accident in strong winds, where she rammed a ferry in Hamburg - perhaps her rudder is insufficient to steer her in strong winds.
Suez Canal: Ever Given container ship shifted from shoreline
Published
in 56 minutes
The stern of a huge container ship that has been wedged across the Suez Canal for almost a week has been freed from the shoreline, officials say.
The course of the 400m-long (1,300ft) Ever Given has been corrected by 80%, according to the Suez Canal Authority.
It added that further efforts to move the boat would resume later on Monday.
But the head of a company involved in the rescue efforts urged caution, warning that completing the operation would not be "a piece of cake".
The Ever Given has been blocking one of the world's busiest trade routes, forcing companies to reroute ships and causing long tailbacks of hundreds of vessels.
(...SNIPPED)
"Haijun" means "navy" in Mandarin Chinese.
"You have enemies? Good. It means you stood up for something in your life."- Winston Churchill
So even larger... I recall doing all the design calculations for the W�rtsil� bow thrusters a while ago...
And indeed, at higher speeds the bow thrusters add nearly nothing to the manoeuvring characteristics, so I would not expect that they had anything to do with this incident (in contrast to ramming a ferry as Maxim indicated?)
The Suez Canal speed limit is between 7.6 knots and 8.6 knots.
The 2 canal Pilots were in charge of manoeuvring at the moment of the incidents...
Did the pilots think that the ship's course would be easier to maintain at 13.5 knots because of the wind conditions? the investigations and the VDR Voyage Data Recorder (The ship "Black Box") will tell us.
The squat effect could be also a factor at this high speed, The ship can be less manoeuvrable, the draft can be reduced from several meters.. This calculation of max speed is done (compulsory, ISM code) before the canal entrance.
Iceman 29 wrote:The squat effect could be also a factor at this high speed, The ship can be less manoeuvrable, the draft can be reduced from several meters..
Can you explain this? I have read several times that a ship is less maneuverable at low speeds, something which you also seem to indicate with "Did the pilots think that the ship's course would be easier to maintain at 13.5 knots because of the wind conditions?"
Shallow water effects combined with the narrowness of a canal can have a large effect on squat, more so the faster you go. From this report from our esteemed facility we measured half a meter for an ULCC at around 13 knots at around 22meters, and that's without canal wall effects.
Low maneuverability plus effect of the canal walls (attraction) plus the wind? Obviously, some ships managed these conditions, whereas Ever Given had already two accidents.
I do wonder! I hope our folks at manoeuvring will be able to solve this mystery and produce a hefty report! (I only do propellers... never an incident with propellers...)
One force on a ships maneuverability that I have not seen mentioned is 'bank suction'. In a narrow channel, as the ships speed increases, the fluid flow between the ships hull and the bank(s) of the channel produce a Bernoulli effect - the same principle to allows airplanes to fly. As a ship inches ever closer to a channel bank the water flow between the bank and the ships hull speeds up, produces a Bernoulli effect that literally 'sucks' the ship towards the bank. (It will also normally yaw a vessel when this happens just like what we saw with Ever Given.) If the Ever Given was, in fact, traveling at 13+ kts in the Suez, and the canal is pretty darn narrow where this incident happened, it would not take much of a deviance from centerline to induce bank suction. And once it has you its very difficult to break the pressure hold on the hull.
Iceman 29 wrote:The squat effect could be also a factor at this high speed, The ship can be less manoeuvrable, the draft can be reduced from several meters..
Can you explain this? I have read several times that a ship is less maneuverable at low speeds, something which you also seem to indicate with "Did the pilots think that the ship's course would be easier to maintain at 13.5 knots because of the wind conditions?"
Sure!
The faster you go the more efficient the rudder, the more efficient the hull, the less the ship drifts. The ship is more maneuverable, better defended as they say. These ships have flat bottoms, they are "soapsuds" on the water, especially with this air draft.
For the squat this video explains the phenomenon seriously:
I wonder if it was not simply sail effect through overloading. Ever Given had almost the maximum number of containers on deck with a 'sail' area the pilots may not be used to. Until recently load factors on these very large container ships were not that high so they would have much more responsive. I think bernoulli effect would have mattered but not at the start of the incident. The canal is not that narrow (about 4 times the beam of the ship). A possible scenario would have been some deviation from the centerline of the canal due to wind sail effect at first, the bow getting close to the shallower part of the canal lead to the bow being sucked to the edge (bernouilli effect between the canal edge and the bulbous bow) and as the pilot saw the ship moving out of control he ordered a sharp correction using the rudder. In doing so the rudder 'stalled' and the resulting braking forces swung the stern away until it hit the other side of the canal. Despite this the ship still had significant forward momentum which was spent embedding the ship into the edge. If the bottom was sandy or clay-ish the momentum also solidified the bottom and edge of the canal, making it harder to remove the ship. Solidified sand and clay can become rock-hard, the famous (in NL ) Eastern Scheldt storm surge barrier was build on solidified sand for example.
Mer et Marine 
