Jesse

Sailors Used To Pour Oil on Raging Seas to Calm Them. The Crazy Part Is That It Actually Worked. | Mihai Andrei, ZME Science On November 15, 1883, a ship called the Grecian was sinking in a raging storm. Towering waves battered its hull, and the crew had little hope of escaping. A nearby vessel, the Martha Cobb, wanted to help. But the breaking waves were so violent that launching a rescue boat seemed almost suicidal. Then Captain Thomas Greenbank tried something that sounds outright weird. He poured roughly 19 litres (five gallons) of fish oil into the sea. According to accounts, something even weirder happened then. About 20 minutes later, the waves were still enormous, but their violent, breaking crests had seemingly disappeared around the two vessels. Beyond this strange patch of calmer water, the sea continued to rage. A small boat was launched. All ten men aboard the Grecian were rescued. Greenbank described the transformation as “magical.” It’s easy to dismiss this as a sailor’s tell tale. But here’s the thing. The rescue was documented, the practice had been done for centuries, and one remarkable study explained how it worked. Storm oil really is a thing. From the Romans to Benjamin Franklin Long before modern meteorology, sailors had a peculiar weapon against rough seas: oil. The practice was known in various forms for centuries. The Roman naturalist Pliny the Elder mentioned it in the first century AD, describing how divers released oil to smooth the water’s surface and allow more light to penetrate. The logic was practical. A rough surface scatters and refracts light in different directions. A smoother one makes it easier to see below. But could it actually calm a storm? The practice can be traced back as far as 350 BC with Aristotle. It was carried out for centuries during Roman time, and apparently, continued until the whaling days, when vessels “dangled blubber” around the hull when in heavy seas to help calm the ocean. But sailors do many things, and some of them were pure superstition; there’s a reason why sailing tales are often regarded with skepticism. Yet at least one famous scientist was intrigued by it; one called Benjamin Franklin. Wind and oil In 1757, while crossing the Atlantic with a fleet of sailing ships, Franklin noticed something curious. The water behind certain vessels appeared unusually smooth, even as the surrounding sea was ruffled by wind. A captain explained that greasy waste thrown overboard could produce the effect. It was the storm oil. Franklin, as any respectable scientist, was skeptical. But years later, he decided to investigate. In 1773, standing beside a wind-ruffled pond at Clapham Common in London, Franklin poured a little olive oil onto the water. Initially, nothing much happened. The wind simply pushed the oil toward the shore. So, he moved to the other side of the pond, where the wind was coming from, and tried again. That’s when he saw it. A teaspoonful of oil spread across the pond, smoothing an area Franklin estimated at perhaps half an acre, approximately 2,000 square metres. He described the surface as being “as smooth as a looking-glass.” Storm oil was real, and it worked. His observations were published in Philosophical Transactions in 1774, making them one of the earliest scientific investigations of the phenomenon. And Franklin noticed a crucial detail: the oil wasn’t stopping all the waves. During subsequent experiments at Portsmouth, the larger swells continued travelling through the oily patch, even though the surface looked noticeably calmer. How can a tiny amount of oil change the sea? An ocean wave contains an enormous amount of energy. How could a film of oil, sometimes just a few molecules thick, possibly make any difference? The answer begins with something deceptively small: ripples. Ocean waves exist on many different scales. There are enormous swells generated by distant storms, smaller waves driven by local winds, and tiny ripples known as capillary waves, which are strongly influenced by surface tension. These small ripples are more important than you’d think. They contribute to the ocean’s roughness and help determine how efficiently wind transfers momentum and energy into the water. Oil can interfere with that process. Certain animal and vegetable oils spread efficiently across water, forming exceptionally thin films. Their molecules interact with the water surface, giving the film properties quite different from those of clean water. As waves travel through the film, they repeatedly squeeze its molecules together and pull them apart. Where the molecules become crowded, the surface tension changes. Where they spread out, it changes differently. These differences create forces called Marangoni stresses, which oppose parts of the surface’s motion and increase energy dissipation. Think of it as a tiny, constantly shifting resistance to the movement of the water’s skin. The result is that small waves can be strongly damped. But this affects the waves even more. When those tiny ripples disappear, the wind encounters a smoother surface. Under some conditions, that changes the flow of air over the sea and reduces the energy available to sustain larger wind-driven waves. The oil isn’t physically holding down a giant wave. It is changing how the wind and ocean interact. It’s such a fascinating effect that modern scientists also wanted to look into it. Modern experiment showed the effect was real For centuries, evidence came mostly from sailors’ accounts and relatively simple experiments. With modern cameras and experimental setups, there was more work to be done. So, scientists got to work. In 2019, researchers published an experiment in Ocean Science that demonstrated just how dramatically a thin film of fish oil could affect wind-generated waves. They used a large experimental tank, with wind blowing across the water at a reference speed of six metres per second, roughly 22 kilometres per hour. Without oil, waves developed across the surface. With a thin film of fish oil, the normal formation of wind waves was almost completely suppressed. The remaining surface fluctuations were tiny, on the order of a millimetre. The aerodynamic stress exerted by the wind on the oily surface also fell by a whopping 95%. A 2023 study in the Journal of Fluid Mechanics revealed another fascinating piece of the puzzle. Researchers generated plunging breakers — the kind of waves whose crests curl forward and crash into the water — in a laboratory tank. When small amounts of surface-active substances were introduced, the shape of the breaking waves changed dramatically, including how their curling jets formed and trapped air. Crucially, the researchers found that differences in surface tension across the moving wave mattered more than simply lowering the average surface tension. Granted, a controlled wave tank is not the North Atlantic in a hurricane. But the experiments seem to support the practice. This trick was mandatory for decades In 1888, British lawmakers debated whether ships should be required to carry oil for emergencies. Six years later, the Merchant Shipping Act of 1894 explicitly included “oil for use in stormy weather” among the lifesaving supplies that maritime authorities could require. In the United States, the practice went even further. By 1952, federal regulations required certain lifeboats to carry a full gallon (3.8 litres) of storm oil. Sailors could release it gradually from a container near a sea anchor, spreading a thin film across the path of incoming waves. Imagine that: for generations, something as ordinary as fish oil was considered potentially lifesaving equipment, alongside the tools and provisions sailors depended on to survive at sea. The US requirement wasn’t eliminated until 1983, as modern enclosed lifeboats made the practice increasingly obsolete. Today, deliberately releasing oil into the ocean is not a recommended storm-survival technique, not least because of its environmental consequences. For centuries, sailors believed they could calm the sea with a little oil. They didn’t understand the molecular forces involved, the complicated relationship between waves and wind, or the physics of surface tension gradients. They simply observed something useful and tried to make it work (and saved a lot of lives in the process). More than two thousand years after Pliny described the phenomenon, and more than 250 years after Franklin experimented with it, scientists are still uncovering the subtleties of how a microscopic film can influence the enormous, restless surface of the ocean. Sometimes, an old sailor’s tale turns out to contain a surprising amount of science. zmescience.com/science/news-…