Is bauxite really new cargo? Or do they mean ship-operators need to be careful when switching to bauxite cargo?
And any particular reason for loading these cargoes with water? Why not dry?
"The International Maritime Organisation has 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."
My read on it was that bauxite was new as a solid bulk cargo, not that bauxite itself was a new cargo in general. I know nothing of the industry however, so I'm not sure whether this is a legitimate interpretation or not.
Ideally, is mined, then either stored somewhere dry, out of the weather, or delivered directly to the ship in a covered train/conveyor belt.
In reality, it's usually mined, then stored in a big pile outside in the weather for weeks/months until it's loaded. It won't pass the pre-loading transportable moisture limit (TML) tests, so they falsify the results.
A cargo with a slightly high TML can appear dry on loading, but the vibration causes the moisture to migrate down to the bottom of the hold and cause the cargo at the bottom to liquify. When the ship rolls, this layer shifts, and the rest with it.
Obviously, if the TML is way too high, the whole thing turns to slurry.
Autonomous and underwater would be hard, radio doesn't travel well through water.
>The International Maritime Organisation has codes governing...
The old way of indicating "this is a link" was underlining. That seems to have largely fallen out of favor and most websites seem to use color coding these days.
https://en.wikipedia.org/wiki/Mr._Midshipman_Hornblower
"Hornblower and the Cargo of Rice"
I'm asking because it's a fictional story and the sink ships because of the wet rice expanding. It doesn't actually save the ship, though it does likely delay its demise.
https://en.wikipedia.org/wiki/Free_surface_effect
https://en.wikipedia.org/wiki/Metacentric_height
tl;dr version as I recall: keep holds either mostly full or mostly empty, make assymetric holds and tanks, and use baffles if you have no other options.
What the article talks about is 2-phase cargoes, cargoes which are expected to behave as solids but could turn to liquid under certain unpredictable conditions.
Accounting for these scenarios might involve upsetting the economics of said cargo.
Edge cases basically :D
Think of box with a grid inside it
Once the cargo is filled
The grid lines are raised (hydraulics) which compartmentize the whole cargo into blocks.
Invidual compartment will not have enough mass of material inside it to break the dividers if designed properly.
It's probably cheaper to just have baffles and vacuum the cargo out.
The status quo is cheaper still
Discussion of the original article: https://news.ycombinator.com/item?id=17884382
Not sure what led to my submission of the BBC article from 10 months ago being targeted for a re-post.
But thanks for the link to the earlier discussion!
Drying that would require a lot of area, effort, and sun, or some type of oven. Any method of making sand drier costs orders of magnitutde more than the sand itself.
the cargo containers should just vibrate the whole time to keep things in liquefied state throughout the whole trip.
