F
OR MORE THAN EIGHT DECADES, the Navy Experi- mental Diving Unit (NEDU) has been on the forefront of technological advancement in virtually all aspects of deepwater diving. State-of-the-art breathing units, advances in submarine rescue, sea-floor habitats, safer deep-sea salvage, and improved diver decompression are just a few of the unit’s scientific achievements.
“We work with the fleet and the warfighter to provide timely and cost-effective solutions to support and improve manned operations in undersea and other extreme envi- ronments,” says Navy Cmdr. Keith Lehnhardt, commander of the NEDU. “We do this in two ways: with biomedical research and through independent tests and evaluation of equipment and procedures.” The NEDU’s mission is support of military divers, but the results of its work have benefited the ci- vilian sector as well. Recreational divers who have relied on *stan- dard decompression tables, for example, can thank the NEDU for enabling a safer excursion.
* 52 MILITARY OFFICER JULY 2012
Early developments The Navy formally started research into experimental diving in 1912 at the Brooklyn Navy Yard in New York under the di- rection of Navy CWO George Stillson, who felt the Navy div- ing community at the time was inefficient and lacking in proper equipment. Under Stillson’s di- rection, the group tested Scottish physiologist Dr. John Haldane’s theories regarding staged de- compression, developed the first standard Navy diving equipment, and extended the maximum diving depth of Navy divers from 60 feet to nearly 300 feet. By comparison, modern Navy *satura- tion diving can be done to a depth of 1,000 feet and has been done experimentally at the NEDU to 1,800 feet.
In 1915, Stillson’s group put its advances to the test when it was sent to Honolulu to assist with the salvage of the USS F-4 (SS-23), a submarine that sank in 304 feet of water. One dive was accomplished at that depth, and several successful working dives were made to 204 feet. However, the divers were plagued by nitrogen narcosis, a dangerous form of mental impairment attributed to breathing compressed air. A safer breathing medium was needed. The end of World War I halted
Standard decompres- sion tables list ascent
rates and breathing mixtures to pro- vide safe pressure reduction (either staged or continuous) to atmospher- ic pressure after a dive. If care is not taken to decompress, nitrogen gas can be released from solutions in the body and form bubbles in body tis- sues. This decompression sickness, or “the bends,” can present as joint pain or even numbness and paralysis. Saturation diving relies on divers remaining at a constant high pres- sure (at which their body tissues are “saturated” by gases) for the dura- tion of a long project instead of un- dergoing frequent decompression.
most Navy diving research and also saw the closing of the Navy Diving School in Newport, R.I. Through much of the 1920s, the Navy’s only ongoing studies were to evaluate helium as a safer breathing medium. This research, done in cooperation with the Bu- reau of Mines, proved the efficacy of combining helium with oxygen to prevent nitrogen narcosis.
Research revs up Research rapidly resumed when the NEDU officially was established at the Washington Navy Yard in Washington, D.C., in 1927, and the Navy School of Diving reformed under a separate command. “One of the main developments during that
time was the Momsen Lung, a submarine escape device that allowed trapped submariners to escape and safely as- cend to the surface,” says NEDU research physiologist Dr. Wayne Gerth. “There was also the development of the Mc- Cann Bell, another rescue device for submariners.”
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84