Container ship breaks in half and sinks

[John Arton]

The latest Maersk triple E class are 400 mtrs long.
These container ships are double hulled built on box girder principles running fore and aft at their sides and as they are so wide have box girders running fore and aft under the main deck. Hatches can be around three across but unlike tankers these hatches are not divided by fore and aft bulkheads, just the box girders underdeck.
When I was on container ships weights of the containers in a lot of cases were only estimates, e.g. a 25 foot container was always calculated as weighing 25 tons in the pre planning stage, unless its weight had been declared. Container weights were always a problem but over the years and due to legislation their true weight should be known to the ship planner. Remember most container stow plans are worked out ashore before the ship arrives and are only checked on board to ensure that such things as containers of dangerous goods are stowed correctly apart.
The planners use the same stress loading software that is onboard so in theory the ships should be loaded correctly and within their stress limits, but theory is fine, practise is different.
If you look closely at the pictures of the ship before it broke up, the split appears to have started some way down the ships side and not at deck level as you would have expected which leads me to think that there must have been weakness in the double hulled box girder.
One other thing. The reason why these big container ships have the accommodation and engine room around 2/3 of the length from fwd. is that if you were to place them right aft then with all cargo holds forward of the bridge then as the cargo area is basically just an empty box, you could never build sufficient strength into them, so the engine room and accommodation are placed there to basically put a very strong cross sectional area into the ship, despite meaning that you have to build long shaft tunnels for the propeller's.
I would hazard a guess that these ships always sail hogged so if incorrect weights are declared then that could mean that even though the stress loading calculations are o.k. the ship could be overstressed.
Modern container cranes do weigh each container as its loaded and in a number of terminals world wide this is automatically transmitted to the planner and ship and in some cases the stowage plan is automatically updated in real time. However by this stage it is too late to change anything as two minutes later another container would be loaded on top of the container and if it was overweight, to take it out and restow it would just take too long a time causing delays.
Regarding salvage tugs.
My father was taught all he knew about salvage and towage by the Dutch during the war. Three Dutch tugs had escaped Holland before the country was overrun by the Germans and when father signed up he was put in charge of a deep sea rescue tug where amongst them were these three Dutch tugs and their skippers taught him the ins and outs of salvage. After the war they were annoyed with him for joining Overseas towing instead of working for them.
The last U.K. deep sea salvage tug John Ross, ended up in South Africa if I recall correctly and she was almost a sister to the SMITS salvage tugs of the time.
I went on board the SMITLLOYD Rotterdam in Durban many years ago for a visit and was treated to a tour of her. Absolutely fascinating all the gear she had even down to the workshops where anything you could think off that you would need during salvage work or towage could be knocked up if it was not already on board.
I guess that they are still the world leaders in salvage despite the American outfit being in the spotlight due to the series on SKY.
Right that it, I'm off to celebrate the Lions win, bit of a cracker of a match and you have to feel for the poor spot kicker who slipped when taking that last minute penalty. Plenty of work to do though before the Lions can say they are the better team.
rgds
JA

[Don Rafferty]

Is there any rule-of-thumb for how much tug horse power is required to move a given tonnage of shipping, I know harbour work is likely to be different to deep-sea and expected weather conditions will all have to be considered, but is there a figure?

[Tony Wilding]

in the 60s and 70s, were all these stress factors in operation when loading Ships, ? i realise Cargo had to be stowed in the correct order for discharge, i know Ships have allways Hogged and Sagged, but not to the extent of modern Ships, there is a Type of Cargo carried by Ore Carriers, mostly from Indonesia, that if too wet when loaded Liquefies, with fatal results for the Ship and Crews, many of these Ships lost in the past 2 years, with most of the Crews, so much for testing the levels of water content. its getting dangerous going to Sea now, and no lessons learned.

[John Cassels]

John Arton ; In all the years I've worked with container vessels , I've never heard of a 25 Ft. container. Also the average weight
of a 20 ft container has long been accepted as 14 mt.
Also your point re stress calculations ashore is not as i remember. The pre plan was done ashore , but acceptance of same
together with stability/stress calculations was always done on board - AS IT SHOULD BE.

[Tony Wilding]

MOL COMFORT LATEST, Sea State still adverse, Two Tugs it is thought from Smit ETA June 24, Patrol Boat same ETA, no other changes.

[j.sabourn]

Usually a tugmaster talks about bollard pull. The tows I did think we had a bollard pull of about 80 tons this was on a just below 5000 B.H.P. Also when shifting a rig if there were doubts, 2 tugs were put on the tow, one on the bridle and one towing from a secure point on the rigs pontoon. Both towing vessels would tow the leading tug on the bridle and the second tug about half a ships length behind. All alterations of course was given by the lead tug and the lead tug altered and other one followed almost at the same time, both vessels close together. As said in a previous post think the least B.H.P. now required in the North Sea is 16000 H.P. others may have more recent knowledge than me as maybe even higher. The bollard pull of these vessels must be well in excess of 200 tons. Most of the larger H.P. vessels have 4 main engines, 2 on each shaft when towing on 4 engines used to burn in excess of 30 tons a day. When not towing 2 engines were declutched for obvious reasons. I mentioned a Pelican hook not realizing that some may not know what it is, it is a much larger and heavier slip the same as a Senhouse slip, this is attached to a 35 mm wire and when disconnecting tow had to release with a 28 lb. maul, the wire could go any way depending on weather conditions an ships movements, this was always the mates job and very hairy at times, other methods more modern now used. Cheers John Sabourn

[j.sabourn]

Tony think you are referring to either Zinc Concentrates or Copper Concentrates. All ore and concentrates has a moisture factor, in fact on some charters especially to Russia there used to be a clause in the Charter Party how much water content they were allowed, and they used to put a hose down the hatch to make sure they weren't short changed. However with either of the concentrates mentioned the water content instead of draining through to the bilges came to the surface and finished up with a free surface effect on top of the cargo. There was a ship actually lost which loaded in Esperance prior to 1964. I think after that temperatures etc had to be taken 2 or 3 times a day, I forget what the temperature was that water was expected to come to the surface. Cheers John Sabourn

[John Cassels]

Was it not more a question of movement and vibration rather than temperature that caused surface water in a concentrates cargo ?.

[Ivan Cloherty]

Was it not more a question of movement and vibration rather than temperature that caused surface water in a concentrates cargo ?.

John if I remember correctly, it was a combination of all three, I know we used to take a sample from first couple of hundred tons loaded and carry out an angle of repose test and moisture content test (in warm conditions) and obtain a certificate confirming the qualities from the shippers. The Temp was important if loading in cold ports and traversing tropical zones as the frozen ores could give a false moisture content, but as usual I stand to be corrected, as it was a very very long time ago.

[Tony Wilding]

hi John, i came across this about Zinc Concentrates a couple of weeks ago, a big write up about on it on GCaptain, stating how dangerous it has become to load this Cargo in Indonesiia, regarding the the accuracy of details of water content, intentional or otherwise, then gave names and details of recent Ships and Crews lost, i have only experienced the effect of free flow surface water in a small boat that leaked like a seive when first launched, ok after a couple of hours, you lose complete control, had to launch it in complete darkness, then proceeded to Row about 50 Yards to my Boat, with my Fishing Gear and Starting Handle, it was a 10 foot flat bottom dinghy, had gone about half way and the boat was not handling right, then when my feet got wet i knew water was inside, the slightest movement and she nearly tipped over, only just made it to my boat , was scary in the dark,