Are ghost ships real? - Peter B. Campbell — Transcript

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1. 0:08One foggy morning in 1884,
2. 0:11the British steamer "Rumney" crashed into the French ship "Frigorifique."
3. 0:16Seeing their ship filling with water,
4. 0:18the French crew climbed aboard the "Rumney."
5. 0:21But as they sailed towards the nearest port,
6. 0:24a silent form suddenly emerged from the fog:
7. 0:27the abandoned "Frigorifique."
8. 0:30It was too late to turn,
9. 0:31and the impact was enough to sink the "Rumney."
10. 0:35As the sailors scrambled into the lifeboats,
11. 0:37the empty "Frigorifique" sailed back into the fog,
12. 0:40having seemingly taken its revenge.
13. 0:43In reality, the French sailors had left the engines running,
14. 0:47and the "Frigorifique" sailed in a circle before striking the "Rumney"
15. 0:51and finally sinking.
16. 0:53But its story became one of the many tales of ghost ships,
17. 0:57unmanned vessels that apparently sail themselves.
18. 1:01And although they've influenced works like "Dracula"
19. 1:04and "Pirates of the Caribbean,"
20. 1:05crewless ships aren't the product of ghostly spirits,
21. 1:09just physics at work.
22. 1:11One of the most famous ghost ships was the "Mary Celeste"
23. 1:15found sailing the Atlantic in 1872 with no one aboard,
24. 1:20water in its hold,
25. 1:21and lifeboats missing.
26. 1:24The discovery of its intact cargo and a captain's log that ended abruptly
27. 1:29led to wild rumors and speculation.
28. 1:32But the real culprits were two scientific phenomena:
29. 1:36buoyancy
30. 1:37and fluid dynamics.
31. 1:39Here's how buoyancy works.
32. 1:41An object placed in a liquid displaces a certain volume of fluid.
33. 1:46The liquid in turn exerts an upward buoyant force
34. 1:50equal to the weight of the fluid that's been displaced.
35. 1:53This phenomenon is called Archimedes's Principle.
36. 1:56Objects that are less dense than water,
37. 1:58such as balsa wood,
38. 1:59icebergs,
39. 2:00and inflatable rafts
40. 2:02always float.
41. 2:03That's because the upward buoyant force
42. 2:05is always stronger than the downward force of gravity.
43. 2:09But for objects or ships to float when they're made of materials, like steel,
44. 2:13that are denser than water,
45. 2:15they must displace a volume of water larger than their weight.
46. 2:19Normally, the water filling a ship's hull would increase its weight
47. 2:23and cause it to sink—
48. 2:25just what the "Mary Celeste's" crew feared when they abandoned ship.
49. 2:29Instead, for reasons we don’t know,
50. 2:31the water stopped coming in before the weight of the water
51. 2:35was enough to sink the ship.
52. 2:37The “Mary Celeste” was found a few days later
53. 2:40while the unfortunate crew never made it to shore.
54. 2:44Far stranger is the tale of "A. Ernest Mills,"
55. 2:48a schooner transporting salt,
56. 2:50whose crew watched it sink to the sea floor following a collision.
57. 2:54Yet four days later, it was spotted floating on the surface.
58. 2:59The key to the mystery lay in the ship's heavy cargo of salt.
59. 3:03The added weight of the water in the hull made the vessel sink,
60. 3:07but as the salt dissolved in the water,
61. 3:10the weight decreased enough
62. 3:12that the force of gravity became less than the buoyant force
63. 3:15and the ship floated back to the surface.
64. 3:19But how do we explain the most enduring aspect of ghost ship legends:
65. 3:24multiple sightings of the same ships hundreds of miles and several years apart?
66. 3:30The answer lies in ocean currents,
67. 3:33which are like invisible rivers flowing through the ocean.
68. 3:36Factors, like temperature,
69. 3:38salinity,
70. 3:39wind,
71. 3:40gravity,
72. 3:41and the Coriolis effect from the Earth’s rotation
73. 3:43create a complex system of water movement.
74. 3:47That applies both at the ocean's surface and deep below.
75. 3:52Sailors have always known about currents,
76. 3:55but their patterns weren't well known until recently.
77. 3:59In fact, tracking abandoned ships was how scientists determined the shape
78. 4:04and speed of the Atlantic Gyre,
79. 4:06the Gulf Stream,
80. 4:08and related currents in the first place.
81. 4:11Beginning in 1883, the U.S. Hydrographic Office
82. 4:14began collecting monthly data that included navigation hazards,
83. 4:18like derelict ships, whose locations were reported by passing vessels.
84. 4:23So abandoned ships may not be moved by ghost crews or supernatural curses,
85. 4:29but they are a real and fascinating phenomenon
86. 4:32born through the ocean
87. 4:33and kept afloat by powerful, invisible, scientifically studied forces.