The APL China incident was in Nov of 1998. It was the largest financial loss by any container ship at that time.
Now that incident is thought of with regards to parametric rolling but 1998 was before awareness of that phenomena had seeped into the maritime community.
At the time as I recall the story of the APL China was about the possibility of overconfidence regarding these very large (at the time) ships and the unusually intensity of the storm that struck the APL China and several other ships.
Now ONE Apus has set a new record for loses. Too early to know what happened on the ONE Apus but these bits and pieces explanations, poor lashing etc, don’t really seem to add up.
The MAIB recommends using correct container weights, which is a logically sound solution but in practice when determining motion limits some margin of error should be used to account for the fact that the container weights are not accurate.
Same with poor lashings. Is the assumption being made that they are always OK? Or that the crew will find and correct problems?
If incorrect assumptions are at the heart of these huge losses then at some point it’s going to be time to have a second look. If not after the ONE Apus incident then when?
Considering that a container is identified with machine readable placards and can easily be cross checked with the database of bills of lading which give the declared weight, why on Earth are container cranes not fitted with weight sensors providing data to a program that cross checks actual weight with declared weight so that a mismatch would instantly be identified.
This should also be able to be performed when the side loader or straddle carrier lifts the box earlier in the process.
This could occur while the container is still inches above the trailer and rejected for loading onboard. It seems like this would put the responsibility and cost on the container packer, not the ship.
Lashing of container carriers is dimensioned in such a way that the racking loads and the vertical loads on container corners do not exceed ISO Standard strength limits and uplifting of container corners does not happen. The lateral design accelerations are calculated taking into account ship size, initial GM, longitudinal and lateral location of the container stack and its height, using either direct seakeeping calculations or tabulated values for the most typical cases.
From the recent incidents one can conclude that the strength limits are exceeded. The question is how this could happen and what the maximum values were in these cases. Research is necessary by means of for instance stress gauges and sensor systems. Camera systems could help but are probably useless during night time.
Measurement is necessary of lateral accelerations of both the static loads from container weights and dynamic loads due to ship motions, wave impacts and wind. Also important is to measure the weight forces present during stormy weather circumstances at the bottom layer of containers and the forces of relevant lashings, rods etc.
The bottom line is container weight is the major component of all design elements. Weigh the damn containers and reject all that exceed the limits of the stack in which it is placed. All the research and data collectors onboard are useless if the singular element on which decisions are based is incorrect.
I recall when we had those on the TAPS tankers. Real time stress and strain information was displayed on a screen in the wheelhouse. Only problem was mates used max limits as the target and the ships still cracked.
The reason I bring up the APL China is because parametric rolling can come on very suddenly and without warning. Small changes in wave encounter frequency can cause very large changes in ship motion.
I wonder if something similar yet unknown is happening with theses ULCS? Maybe having to do with the lack of roll dampening as happened on the MSC Zoe.
Are these big rolls happening without warning from small changes in sea conditions?
By most published reports, that question has been answered in the negative.
I think there is no enforcement because the industry chooses to ignore the rule and shippers are only too happy to pretend it doesn’t even exist.
Maybe if shippers got charged for weight overages the carriers would pay more attention to reality rather than fictional bills of lading and make a few more dollars doing it.
My gut instinct suggests that loaded containers may not be strong enough to be stacked 10 high on a ship that is rolling, pitching, pounding, and flexing in heavy weather.
Why would anyone expect containers to stay onboard when the lashing do not go to the top of the stack? That seems kind of like expecting nothing but gravity to keep the roof on the house, it works fine until there is a hurricane.
That’s what I don’t get. I deliver cars with even the slightest problem and I never hear the end of it. Theses container ships are coming in with half the above deck load missing and it’s just: “Well shit happens, better luck next time”?
In a way that is like torquing a bolt so that it doesn’t loosen under cyclical loads, you have to put more force on the bolt than you expect that bolt to see in operation.
If we applied that same principle to container stacking the force would have to be so high that the bottom container would look like it went through a car crusher. Or all the containers would have to be built to withstand more than the greatest conceivable load and then would weigh more than the contents. Not to mention the ship would have to have structural elements to transfer all that compressive load to some sort of foundation that would probably weigh so much that stack height becomes irrelevant unless ship size is doubled.
I think boxboat capacity may already be at or beyond the practical limits.
Possibly, but on the other hand number don’t lie, it should just be a matter of doing the calculations.
The ONE Apus has a beam of 50.6 meters (166 feet) , presumably the max assumed roll is less than the non-ULCS size ships.
This is from the MAIB report posted upthread,
At about 0127, the ship unexpectedly rolled 20° to starboard, paused for several seconds, then rolled 20° to port, initiating the collapse.
“The amplitude of the ship’s rolling exceeded the limits set by: CMA Ships for the class of vessel; displayed by the loading computer and calculated by Bureau Veritas after the accident,” the MAIB said in its conclusion.
Maybe the only way to massage the numbers is to increase the beam to lower stack height.
But then we are back in the old bigger ship, deeper draft, fewer ports spiral but now have to add crane issues. Maybe some day there will be one or two container ports on each coast with special berths that allow mega max beam ships to be worked from both sides at once.
Today the weather forecasts are very good. The weather routing software I used showed areas where synchronous or parametric rolling would be expected, limits exceeded etc.
I set motion limits and the software and shore-side routers comes up with a route. More to it then that of course but it’s takes more work now then ever to hit heavy weather unexpectedly.
Yet incidents like ONE Apus keep happening and have for years. I remember seeing an exact copy at the dockside in Yokohama way back in the 90s so it isn’t exactly a new phenomenon.
Maybe that is why the “Well shit happens, better luck next time” approach still rules the boxboat industry.
In the case of the APL China it wan’t just a matter of exceeding weather limits. The ship didn’t behave as expected. Far heaver rolls then expected for that sea state.
I’m wondering if something similar isn’t happening with these ULCS? The ONE Apus was being managed by NYK. They are a very conservative company.
I was wondering the same thing regarding weighing them as they are loaded. I know they have limit switches on the cranes that have to be manually reset if the container exceeds SWL, but they don’t weigh them as far as I know.
I think you are right, box boats have exceeded practical limits. Especially, concerning port facilities. Soon there may be too many 20,000 TEU container ships that require too many port calls to unload 2000 containers here and 2,000 there. Or dockyards and streets may become clogged for days everytime one of these ships drops a full load or calls to load empty containers.
I fear that we are going to have a lot of multi billion dollar deep channels and high bridges that see few, if any, post Panamax ships.
They found that a 750 ATB instead of having greater economies of scale had less performance at higher operating cost than a tanker of similar capacity.
The last I heard there were too many 80,000 barrel oil barges competing for longer haul and larger terminal cargos, but a shortage of 40,000 barrel barges to deliver smaller parcels to smaller terminals.
I think box boats will start getting smaller again.