In the middle of the ocean, a small fishing boat is floating on the waves. The cabin was filled with golden grain, and the sun shone through the portholes. The boat boss leaned out from the side of the boat and took a deep breath of the sea breeze, a satisfied smile on his face. He seemed to be admiring the wonders of nature, and he seemed to be thinking about something.
At this moment, the hull of the ship suddenly shook violently, and the grain on the deck rolled around like a reservoir dog. Before the boss of the ship could react, he heard a loud "bang", the hull of the ship had been turned upside down, and he and the crew were thrown out fiercely and fell into the sea with a thud. In horror, they watched in horror as the hull of the ship slowly sank to the bottomless depth.
Such a scene is by no means unusual, and there are great risks associated with transporting grain by sea. The reason for this lies in a seemingly unfamiliar but very crucial concept - the "angle of rest". The so-called angle of repose refers to the maximum angle of inclination between an object and the horizontal plane when it stops sliding on the horizontal plane. It may sound a bit awkward, but we can think of it as an inclined plane formed by the accumulation of sand, and the slope is the degree of the angle of rest.
So, why is this concept there? This actually stems from the law of "static friction" in physics. When an object is stationary in a horizontal plane, static friction prevents it from sliding. But once the object is subjected to an external force that causes the angle of inclination between it and the horizontal plane to exceed the "angle of repose", the static friction force cannot prevent it from sliding. Like a snowball rolling down from the top of a mountain, it's hard to stop once it starts to slide.
Returning to our protagonist grains, apparently they are all bundles of granular matter, which perfectly conform to the law of the "angle of rest". Cargo ships are inevitably exposed to wind and waves when moving at sea, and when the hull is rocking, if the angle of inclination is less than the angle of repose of the grain, the static friction can keep the grain in place. However, once this critical point is exceeded, the grain will slide and accumulate on one side, which will seriously affect the center of gravity and balance of the ship's hull, and then capsize and sink the ship.
People often say, "If you walk by the river, you can't get your shoes wet." In 2004, a cargo ship carrying 120 tons of rice capsized at a ferry in Xiangyin County, Jiangxi Province, and all the grain was soaked in water. In an even more tragic accident, in 2014, a bulk carrier named "Jupiter" sank en route to Malaysia, triggering the sparking of the bauxite loaded with bauxite that slid after being deteriorated by moisture during heavy rains, causing the hull to be severely unstable.
In the face of this worrying risk, one can't help but wonder: why not just bag the grain? It sounds more secure and reliable. However, this is not the case, and the probability of a shipwreck due to cargo displacement is actually lower than the probability of an air crash. As a result, despite the risks, bulk transport still dominates.
There are two reasons: one is that the cost of packaging is too high. Packing tens of thousands of tons of grain into bags not only requires a lot of manpower and material resources, but also increases the volume of bags several times, occupying a huge cabin space, which is undoubtedly a heavy burden for shipping companies; Second, the loading and unloading efficiency is low. The traditional use of manual loading and unloading trolleys to carry bagged grains, the low efficiency can be imagined, if you want to mechanize the operation, you must also re-purchase special equipment such as grain suction machines, bagging machines, etc., and the upfront costs and later maintenance costs are expensive.
The modern shipping industry pursues fast, efficient and low-cost in the true sense, so it chooses the bulk transportation method. With the help of vacuum suction or grab loading machinery and equipment, it can load and unload thousands of tons of goods at one time, which greatly shortens the operation time and greatly saves labor costs. In order to minimize the risk of cargo deviation, the four corners of the grain bulk carrier's cargo compartment have been specially reinforced, and compartments have also been set up to disperse the weight of the cargo. What's more, these dedicated bulk carriers also have filler openings that fill all remaining space and ensure that cargo does not slip extensively during the voyage.
Even so, there are occasional accidents. The size of life is often separated by a thin line. Even a heavily armed professional vessel can be enough to shake the balance of the hull and tilt the side to a critical point in the event of a ferocious storm. Once the "corner of rest" of grain is exceeded, the whole warehouse will be like being stabbed in the middle, all the grain will rush to one side, the center of gravity of the hull will be completely out of control, and the doom of capsizing and sinking will follow.
Every shipwreck occurs, in addition to bringing huge financial losses to the shipowner, it may even cost lives. However, behind this is the hard work of hundreds of millions of farmers. We eat every grain of rice in our home so sweet and delicious, but we often forget that it has struggled to survive in the face of many hardships. From the field to the table, the road is arduous and tortuous, and even the last journey of sea transportation is so dangerous.
Life is indeed fragile, but it is also because of this that we should cherish it even more. When you pick up a grain of white rice with chopsticks again, you might as well imagine how many brave sailors are fighting to the death against the wind and waves on the distant sea, just so that this precious food can be safely delivered to your table and mine.