Flying Dutchman - Explanations As An Optical Illusion

Explanations As An Optical Illusion

Probably the most credible explanation is a superior mirage or Fata Morgana seen at sea.

The news soon spread through the vessel that a phantom-ship with a ghostly crew was sailing in the air over a phantom-ocean, and that it was a bad omen, and meant that not one of them should ever see land again. The captain was told the wonderful tale, and coming on deck, he explained to the sailors that this strange appearance was caused by the reflection of some ship that was sailing on the water below this image, but at such a distance they could not see it. There were certain conditions of the atmosphere, he said, when the sun's rays could form a perfect picture in the air of objects on the earth, like the images one sees in glass or water, but they were not generally upright, as in the case of this ship, but reversed—turned bottom upwards. This appearance in the air is called a mirage. He told a sailor to go up to the foretop and look beyond the phantom-ship. The man obeyed, and reported that he could see on the water, below the ship in the air, one precisely like it. Just then another ship was seen in the air, only this one was a steamship, and was bottom-upwards, as the captain had said these mirages generally appeared. Soon after, the steamship itself came in sight. The sailors were now convinced, and never afterwards believed in phantom-ships.

Another optical effect, known as looming, occurs when rays of light are bent across different refractive indices. This could make a ship just off the horizon appear hoisted in the air.