Dangerous Dirt

Bulk Jupiter

The Bulk Jupiter sank off the coast of Vietnam a couple of years ago. There was one survivor. It was carrying a load of bauxite (aluminum ore) which was supposed to be a safe cargo, I mean it's basically just dirt, but evidently some kinds of dirt are liable to turn to liquid in the bottom of the hold is there is enough pressure and enough moisture in the material. At the bottom of the hold there is plenty of pressure due to all the material piled on top, so the gating factor is the moisture content.

If you were sailing on smooth seas this would not be a problem, but in heavy weather where the ship is rolling side to side, having the cargo turn to liquid means it is going to flow towards the downward leaning side of the ship. This can make the roll worse, and if the seas break over the hatches, and the hatches fail, it can be all over in a matter of minutes.

On average, ten "solid bulk cargo" carriers have been lost at sea each year for the last decade. - Susan Gourvenec

Looks like the Bulk Jupiter may have been the last straw that convinced the powers that be that they needed to look at the problem a little closer, so they did. Bauxite used to be a Class C cargo, but now it's a Class A cargo, which means you need to measure the moisture content.

Via Quora