TedEd: Are ghost ships real?

A TedEd by Peter B. Campbell

In 1884 the British steam ship "Rumney" collided with the French ship "Frigorifique". The French crew saw their boat filling with water and boarded the Rumney. But as it sailed away, the Frigorifique sailed out of the fog and sank the Rumney. What happened? The French sailors had left the engine of their ship on, and it had sailed in a circle before hitting and sinking the Rumney. It became a tale of a ghost ship, ships that seemingly sail themselves without a crew. One of the most famous is the Mary Celeste. It was seen in the Atlantic in 1872 with no crew and water in its hold. The reasons it didn't sink can be contributed to buoyancy and fluid dynamics. Buoyancy works by creating a force up on an object when it displaces a fluid. The strength of the buoyancy is equal to the weight of the fluid that was displaced. This is called Archimedes's Principle. This is why things less dense than water float, while things more dense, like steel boats, need big hulls to float. But if it fills with water, it gets heavier, causing it to sink. However, the flooding of the Mary Celeste stopped when the water reached the equilibrium point, the same level as the hull. This is fluid dynamics at work. Another strange tale is of A. Ernest Miller, a boat transporting salt. It sank in a collision, yet was seen on the surface a few days later. What happened was that the heavy salt in the hold dissipated over time, and it was just enough to reduce the weight of the ship and bring it back up. The final part of the ghost ship legends - multiple sightings of one boat in locations far apart. This can be attributed to ocean currents. Caused by differences in temperature, salinity, and wind, they are like little rivers in the ocean, and they carried ships around the world. This is how scientists identified some of the largest currents, such as the Gulf Stream. So ghost ships aren't supernatural phenomena, but ships kept afloat by the mysterious powers of physics.