As the article mentioned, wave action will cause the center of gravity (CG) of the liquid to shift, and with it the overall ship's CG. This puts the ship in a new stable equilibrium heeled over to that side. If the compartment isn't dewatered, this process can repeat until the 'stable' equilibrium includes upper decks taking on sea water. CG shifts up, righting arm becomes flipping arm, hull experiences stress beyond tolerances, breaches kill remaining buoyancy, and down she goes.
By the way, the easiest way to tell if a ship is in danger of hitting critical (aka neutral aka very very bad) stablility, watch how long it takes to rock from side to side. A ship that has an excessively long roll period and appears to be hanging to one or both sides can in serious danger.
Practical Engineering has a great video on this simple but pervasive technology.
You can fill/empty these of granular cargo using large diameter hoses.
You could also create one or two special storage bins that can be rotated to an arbitrary degree to help right the ship if it gets into trouble. They're carrying ridiculous amounts of ballast, why not put some of it to use as a counter-weight?
You just need open tops and open bottoms in the grid. Open at the top so the cargo can fill the cells between baffles, and open at the bottom so the grid can be raised out of the cargo.
But I think the main problem is cost: not waiting for the rain to clear, not making time to install temporary bulk heads, and so on.
Edit. for example this article from 1998: http://www.gard.no/web/updates/content/52980/shifting-solid-...
Dry goods are supposed to be dry... soak wheat in fresh or salt water for a couple weeks you may as well dump it in the ocean, its rotted (its brewing, technically). The problem is SOME dry goods (bauxite, etc) are not the driest to begin with and of course the usual leaks and accidents.
The crew knows exactly what to do if there's a storm or the engine stops or a fire breaks out, but dry goods are supposed to be dry, so when they aren't, the blind spot kills the crew. You could give up training for storms or fires to run liquefaction drills, but that'll kill more people on long term average, because storms are more common than weird cargo issues. Even if labor money is no object, brains can only hold so much at one time.
From the article:
Yet despite our understanding of this phenomenon, and the guidelines in place to prevent it occurring, it is still causing ships to sink and taking their crew with them.
The International Maritime Organisation have codes governing how much moisture is allowed in solid bulk cargo in order to prevent liquefaction. So why does it still happen?
The technical answer is that the existing guidance on stowing and shipping solid bulk cargoes is too simplistic. Liquefaction potential depends not just on how much moisture is in a bulk cargo but also other material characteristics, such as the particle size distribution, the ratio of the volume of solid particles to water and the relative density of the cargo, as well as the method of loading and the motions of the vessel during the voyage.
Why do you have to do one or the other? ¿Por que no los dos?
There's a similar problem, at scale, for civilisation as a whole. Given a lifespan of 85 years, and working span of 65, we spend 18 years on basic education. The managing/professional class need another 4-6 for undergraduate education, plus 2 for professional degrees, 6-12 for engineering and some medical specialties. We're drawing people into the workforce in their late 20s, early 30s, and hope to get 30-40 years contribution.
At the same time, technology, or practices, or standards, obsolete much that information in 10-15 years.
How many times do you, and can you, effectively retrain someone before their prior knowledge is an inescapable impediment, and there's no useful retraining benefit regardless. Confound further with the distiction between explicit (book-learned) and taxit (experiential) knowwledge. The first can be effectvely taught through technical reproduction: lectures, books, A/V, computer-distributed or aaided materials. The latter requires small-ratio master-student raatios for transmission. Skills lacking sufficient masters (or those effective at training) die out.
Just the standard business "reason" - cost.
I would guess that, for the vast majority of bulk-cargo voyages, there is no noticeable shifting, making it it easy to assume that it is not a risk. A captain who has never experienced the problem is probably less likely to stand up to the shipper (and the ship owner's management, which is an issue in itself) over whether a cargo is fit to ship.
The article linked by pasta shows that the problem has been recognized and regulated, for some cargoes, a while back (e.g. grain in 1982), but the lesson has not been generalized.
Also, the rock eating monsters of Janus VI work well against bauxite liquefaction, and M-113 salt vampire creatures are highly effective against salt liquefaction (but unfortunately there is only one surviving creature).
If a sometimes liquid substance shifts to the side, it may become a solid again and stick there, and then it can happen again and keep building up until the ship can no longer recover.
Liquid transport doesn't have the same problem since you can just pump the cargo out.
Keep the cargo in containers which are always full or nearly so. If it doesn't have room to slosh around or shift, it won't.
The added bonus is that it costs less per volume to ship, if the vessel is always full.
> Commercial agendas also play a role. For example, pressure to load vessels quickly leads to more hard loading even though it risks raising the water pressure in the cargoes. And pressure to deliver the same tonnage of cargo as was loaded may discourage the crew of the vessel draining cargoes during the voyage.
If crews don't want to dump some cargo to restore balance, they surely don't plan to to ship less cargo.
Nothing melts or freezes. More to the point, the motion of the macroscopic objects (rocks, sand, dust, powder) being dumped in by conveyor belt create huge piles that slump in odd ways, as piles form, and then settle oddly.
>In physics, self-organized criticality (SOC) is a property of dynamical systems that have a critical point as an attractor. Their macroscopic behaviour thus displays the spatial and/or temporal scale-invariance characteristic of the critical point of a phase transition, but without the need to tune control parameters to a precise value, because the system, effectively, tunes itself as it evolves towards criticality.
>The concept was put forward by Per Bak, Chao Tang and Kurt Wiesenfeld ("BTW") in a paper published in 1987 in Physical Review Letters, and is considered to be one of the mechanisms by which complexity arises in nature. Its concepts have been enthusiastically applied across fields as diverse as geophysics, physical cosmology, evolutionary biology and ecology, bio-inspired computing and optimization (mathematics), economics, quantum gravity, sociology, solar physics, plasma physics, neurobiology and others.
>SOC is typically observed in slowly driven non-equilibrium systems with extended degrees of freedom and a high level of nonlinearity. Many individual examples have been identified since BTW's original paper, but to date there is no known set of general characteristics that guarantee a system will display SOC.
I’m assuming that means that historically, the refiner owner the pulverizing equipment and shipped in bauxite rock or gravel as raw material. When you hear of liquefaction in terms of earthquake damage, they are always talking about saturation of fine materials. Saturated gravel doesn’t behave as badly as saturated sand or clay.
Similarly, Wikipedia claims bulk carriers have been around since 1850: https://en.wikipedia.org/wiki/Bulk_carrier
Doesn't sound all that new.
Triboelectric charging is not well understood yet, it happens in dust storms and volcanic eruptions where charge is transferred to particulates from the air. As charge increases this results in "dry lightning" or other discharges.
If you wanted a research topic, I think you could look into the hypothesis of whether or not a powdered material could be charged to exhibit liquid properties.
Note that the way these bulk solids are loaded on to ships it typically by conveyor belt where they then drop through the air (charging opportunity) and then dropped into a conductive container (the hull of a steel ship).
If someone has looked into this already I'd love to read the paper on it.
The article has a pretty good description of how liquefaction proceeds: higher pressure -> water present in material reduces contact between solid particles -> material friction reduced -> material behaves like a fluid. If you want more, find a book on basic rheology. I'm certain there are civil engineering textbooks that contain the material.
Further, it does not stand to reason that charged materials would suddenly acquire fluid properties. Solid materials are quite capable of sustaining charge without changing their bulk properties. Prior to significant change, local voltages would exceed the breakdown voltage and the charge would be neutralized.
The title could differentiate between being a total loss at sea, versus sinking while docked in a harbor, at least in terms of statistics and death. Also, how is there not one picture of a listing ship in this article?
Insurers work with ship regulators and ship owners to prevent this, as not only does it mean they've lost the ship and cargo, but picking up a new ULBC is not a quick process.
(Which uses this as it’s source: https://web.archive.org/web/20070408154846/http://www.nautin...)
So, out of around 70K trips, 10 result in ship loss. It's entirely possible that the cost to reduce that loss rate against all reasons for loss and across all 10K ships and 70K journeys is far greater than simply allowing 10 failures.
Those losses are also likely insured against with the cost spread across the 70K trips. The insurance against them is likely therefore cheap.
While that isn't a huge amount compared to say their capital costs it is a non-trivial amount of money.
Note that your $20M ignores the cost of the cargo as well as the cost of the lives lost. The later can tend to get much higher if fixes aren't found for problems that are known since letting ships sink to save some money is negligence assuming a fix can be reasonably found.
I'd assume there are smart people in the shipping industry that have spent a lifetime on such issues. I suspect there is not some "reasonably found" solution that will help.
It may be as simple as surprise severe weather events sink many of those lost - and the cost to protect such a large fleet from rare events is extremely costly.
Paying $3200/trip for insurance against ship loss of this kind is peanuts for protecting a $20M item that generates millions annually in revenue.
And the insurance on the goods (and this $3200) is simply passed on to those paying to ship goods.
Can this situation can be avoided if the loading bay has a cover/lid on top of the material?
As long as the loading bay is 'full' (or the top is movable to fit the cargo) the material won't be able to slosh around, thus preventing the situation described in the article.
Also, we can have articulated baffles that raise into place from below, cutting into the solid material.
I think this is a solvable problem.
Murphys Law is someone will put an aluminum smelter pot on a nuclear powered ship, during a storm the molten cryolite will slosh out of the pot freezing onto one side of the ship, sinking the ship, and we're right back to where we started.
From where below? My understanding is that the bottom of the tank is the hull.
Although possibly you could put baffles in place, tip the grain, then crane them out for unloading.
It’s like an avalanche or rock slide.
From the article, it doesn't sound like it's about trace amounts of water at all. It sounds like water is somehow involved in the loading process...?
I guess you need something solid, and fixed to the boat, so there is nowhere for the material to go.
As an experiment, fill a bowl with sand. Level the sand with a scree bar. Tilt it until you notice sand shifting, and note the angle of tilt.
Now level the bowl and put an inflatable bag on top. Tilt until you notice sand shifting and note the angle.
Further experiment: put a vacuum hose through the center of the bag, and suck air out of the bowl as the bag covers the top. Tilt again. If your bag can make a decent seal against the rim of the bowl, and you keep that vacuum pump running, you can almost flip the thing without shifting any sand.
See also Glückauf, the first tanker designed to transport oil directly in the hold rather than in barrels. https://en.m.wikipedia.org/wiki/Gl%c3%bcckauf_(1886)
I suppose in addition to the measures described in the article, bulk ships could adopt cargo holds divided into more subcompartments (including longitudinally, to reduce risk of capsizing) , similar to tankers.
I’m guessing insurance going to be even more expensive now unless 10 ships a year out of however many ships out there is minimal.
But if you're going to spend the money, maybe you could entirely fix the problem. You'd have to run the numbers!
Think of a ship transporting prisoners in their own little cells. Then think of all the prisoners working together to throw their weight against the walls of the cells at just the right moment in an effort to sink the ship.
The prisoners would only have enough of an effect to make the guards a little nervous. The ore sloshing around in the containers weighs tons and tons, though, enough to actually sink the ship.
I had a hard time reading this part, as the puzzle placement seemed so forced and nonsensical to the plot. What did the Japanese gain from this stunt if it worked? A sunken ship in their harbor leaking mercury from hundreds of smashed jars...?
So they keep the wootz payment, they recover the cargo, and they don't lose reputation by just murdering the crew of a merchant vessel outright. If the merchants capsize instead, that's a shame, and a result of poor seamanship, and they'll just go ahead and pretend to be sad during the salvage operation.
What I did find is Minamata disease, which is a particular set of symptoms from severe mercury poisoning, documented in a town in a bay on the western end of Japan.
Maybe Neal was making some sort of nod to that?
I'd imagine that the exact values are not monitored, so that what is written as "in the hold" and what is actually there are subject to natural variation, which can be asymmetric, and thus theory and practice are not the same thing.
If seawater gets into the mix, it will have more water.
There are thermal phase changes in the liquefication. It can behave very differently at 10 deg C warmer than one expects from 0 deg C warmer.
Over a relatively long trip, with agitation, the mean particle size is going to change. Big particles are going to break into smaller particles. This is going to change the liquefication physics.
YouTube science educator Mark Rober's
"Liquid Sand Hot Tub - Fluidized air bed"
You learn something new everyday
Ore starts out as rock buried in the ground. So, you're going to need to get that out of there. While you could do that with a bloke and a pickaxe I'm sure lots of the processes actually involved add water, even if not terribly much.
Also, this stuff isn't expensive, it's basically just slightly valuable dirt, so if it's stored somewhere they're not going to be keeping it in water-tight containers, it'll be in an open truck, or an open freight car somewhere, getting rained on.
Now, shipping dirty water across the ocean is pointless and costs money, so it's not as though they're going to add more water just for fun, but if the contracts involved don't specify that it has to be less than so-and-so much water in the cargo, then it's nobody's job to ensure it isn't damp.