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While the conquest of space is well underway, having captured the imagination and interest of the world, the same cannot yet be said of the conquest of the ocean depths. Vast underwater areas, such as the Continental Shelf off the eastern coast of the United States, are believed within the potential range of divers, but remain beyond the reach of present-day methods. However, the techniques being developed in the Sealab projects are opening the door to “inner space.” The basic concept of these projects is to furnish a suitable habitat for men on the ocean floor, allowing them to work on the sea bed for long periods without returning to the surface, thus minimizing the frequent, long, non-productive periods of decompression associated with conventional deep diving operations. Sealab I, the first-generation U. S. Navy undersea habitat, was placed in 193 feet of water off Bermuda in July 196f. It was occupied by four men for a period of 11 days. (See D. Groves, “Sealab I,” U. S. Naval Institute Proceedings, February 1965, p. 64.) Based on experience gained from Sealab I, plans for Sealab II were formulated in February 1965, under the supervision of Captain George F. Bond, MC, U. S. Navy, who had conceived and headed the first project. Over-all management and direction would be a joint venture between the Office of Naval Research and the Navy Special Projects Office. This time, the experiment would be conducted at a site 4,000 feet offshore, near the Scripps Institute of Oceanography at La Jolla, California. A number of elements comprised the Sealab II project, most important of which was the undersea habitat. Preliminary specifications were developed by the Naval Mine Defense Laboratory, which had built Sealab I- ’ The final and detailed design and construction of the habitat was assigned to the San Francisco Naval Shipyard. The completed habitat was a cylinder 57 feet long and 12 feet in diameter, weighing 200 tons, with laboratory space and living accommodations for ten men. A diving entrance at one end and an emergency diving trunk at the other were for use on the bottom, while a conning tower permitted access when the habitat was floating on the surface.
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0r Sealab II, a pressurized personnel transfer cap- th e,Was developed to transport the aquanauts from e bottom to the surface, where they would be trans- fred to a larger and more comfortable decompres- *Wn chamber. With a capacity of ten men, the per- nnel transfer capsule was designed to be sealed at °m pressure before being raised to the surface, f base containing the ballast would be removed nor to mating with the decompression chamber. In J1 ernergency, the ballast could be dropped and the cCe.n* controlled by the aquanauts from within by a us r°"'e<^' cable payout mechanism. When not in ®e. the chamber rested alongside the habitat, provid- 9 a refuge should the Sealab have to be evacuated.
The U-shaped surface support vessel for Sealab II consisted of two YFN barges joined together. Nicknamed the Berkone, the craft was 90 feet wide and 110 feet long. On it were a control van, medical laboratory, gas supply system, and atmosphere sampling and control systems. The Berkone also housed the deck decompression chamber (lower photograph) and crane for lifting the personnel transfer capsule. Living and messing facilities for topside personnel were also provided, and an umbilical from the Berkone to the habitat provided the Sealab with an alternate source of power, communication, and gas supply. Sealab IBs normal power and communications were provided by cable from shore.
In July 1965, Sealab II was placed on a barge and towed from San Francisco to the Long Beach Naval Shipyard, and preparations began in earnest. Many last minute tests and changes were made. The 28 aquanauts who would man Sealab II reported for further training and familiarization, having completed preliminary training at the Mine Defense Laboratory, Panama City, Florida. In early August, the deck decompression chamber and personnel transfer capsule arrived from the manufacturer. Exploratory dives were made in the vicinity of Scripps Canyon off La Jolla to determine the best location for the Sealab. The uneven terrain, silty bottom, and depth made this a difficult task.
In mid-August, the commercial salvage ship Gear took the surface support vessel in tow to the selected site, where it was placed in a five-point moor. The moor was particularly important, since the lives of the men in the habitat would be endangered should the moor fail (although the habitat was designed to sustain itself for up to 15 days in an emergency)• In order for the Berkone to perform effectively, H would have to remain within a ten-foot circle, so that the equipment could be precisely lowered to Sealab II. Two legs of the moor had to span Scripps Canyon, and were 1,500 feet long. Power and water lines, attached to a power transformer, were then laid from the underwater site to the Scripps Pier. Then, several troubles struck: the transformer’s legs failed, severing the water and power lines, and divers discovered that the undersea terrain was too precipitous for Sealab II. After considerable work, the power cable, water lines, and power transformer were recovered, and the Berkone was moved to a new, more level location, some 200 feet away. In late August the habitat was sealed (top photograph) and towed to the site, and preparations were made to lower it to the bottom.
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inte ^ea^ak H habitat was designed to withstand an ;.(jurna\ pressure of up to at least 150 pounds per botJXre ln°h, allowing it to be sealed and charged to loy;em,PreSSUre w^e on the surface, and then with - bottom by means of a winch and cable, tanks l*S buoyancy controlled by internal ballast
as ■,71 a,/e over Sealab I, which had to have gas added pres " as towered since it could not withstand bottom baliaUfe’n ani^ which employed cumbersome solid habit i 26 August, after numerous checks the tanks Was Gorged to bottom pressure, the ballast with th^6- fl00(^e(t’ an(t it was lowered to the bottom weighteaid the support vessel’s winch. A counter-
After the habitat reached the sloping sea bed, instrumentation indicated a k-degree list to port and a trim of 10 degrees by the stern. To achieve a more satisfactory angle, it was raised a few feet and repositioned to a 6-degree port list and the same degree of trim by the stern. The following day, the personnel transfer capsule and the redesigned power transformer were lowered into place near the habitat. All instrumentation indicated that Sealab II was operating satisfactorily and was ready for occupancy.
Four divers, including the astronaut/aquanaut, first undersea team leader, Commander M. Scott Carpenter, U. S. Navy, made the initial descent to Sealab II. They employed Mark VI SCUBA, which uses a mixture of helium and oxygen and a recirculating system for carbon dioxide removal. Equalizing valves on the habitat and personnel transfer capsule alongside were opened, permitting the entrance hatches to be opened. The four swimmers entered the habitat, and the remaining members of Team Number One then descended from the surface in pairs. Power and water lines were connected, and Sealab II was manned.
The aquanauts in the Sealab were kept under suf veillance at all times from the surface by closed cf cuit television. Cameras mounted outside, viewing 1,1 through the ports, worked better than those inside the habitat, as the high-pressure helium atmosphere V the Sealab tended to penetrate the vidicon tubes a cause them to malfunction.
The first three or four days on the bottom were devoted to preparing the habitat for operations. The lines used in lowering the habitat were disconnected, internal and external port covers removed, and dumb waiter service to the surface established. Progress was slow because of the darkness and cold water. Donning and removing the rubber diving suits and replenishingj the swimmers’ gas bottles were also time-consuming jobs. The teams devoted a large portion of their time to housekeeping, a job complicated by lack of space, with ten occupants in Sealab II. Team members took turns at galley duty. The diet was not particularly restrictive, although fried foods were not permitted since such cooking would contaminate the atmosphere. The aquanauts were kept very busy by their various scheduled projects. Among other things, breath, blood and saliva samples were taken, and other physiological checks were made as scheduled.
Watertight pressurized canisters were used to transfer some supplies from the surface to Sealab II. Items not damaged by pressure or water were transferred by the dumb waiter in a wire cage. Canisters arriving at the bottom were secured to a block and tackle by a swimmer and then hoisted into the habitat through the entrance hatch. The hatch, seen above, was always left open, since the internal pressure in the Sealab, equal to that of the surrounding water, prevented the sea from entering.
Excursions out to about 200 feet from the habitat were made by the first team. Way stations with emergency breathing supplies were placed on the bottom (top photograph), and a weather station was set up for the measurement of currents, water temperature, and pressure fluctuations. A preventer anchor consisting of a 13,000-pound anchor attached to a 6-inch nylon line was attached to the habitat as an added stability and safety measure. The temperature at the bottom was about 50 degrees Fahrenheit, or less, limiting the divers’ excursions to a maximum of about one hour. Visibility was limited to about 15 to 30 feet, and the bottom was covered by a layer of silt, which when disturbed further reduced visibility (lower photograph).
The atmosphere in Sealab II was rigidly controlled and consisted of a mixture of about f.3% oxygen, 18% nitrogen, and the remainder helium. Compressed air could not be used, since the high content of oxygen at a pressure of seven atmospheres would cause severe pulmonary problems, and the nitrogen would create an unacceptable narcotic effect. The life support system automatically replenished oxygen in the Sealab from bottles stored outside and through an umbilical from the surface support vessel. The umbilical also contained a sampling hose to permit topside personnel to analyze the habitat’s gas mixture. Carbon dioxide was removed from the atmosphere by a recirculation unit using lithium hydroxide as an absorbent. Since helium is much lighter than air, the aquanauts’ vocal cords vibrated at a higher than normal pitch, making their speech difficult to understand. To aid personnel on the surface, a speech “unscrambler” was installed in the voice communication system. As pressurized helium causes rapid loss of body warmth, temperatures in the habitat were maintained at about 86 degrees Fahrenheit. Humidity was always a problem, even with the dehumidification system functioning properly.
After fifteen days on the ocean floor, nine of the ten members of Team One prepared to return to the surface. The day before, inspection of the personnel transfer capsule had disclosed that hundreds of fish, attracted by the lights inside, had entered the chamber and died, and it had been raised and cleaned. Before Team One departed, three members of Team Two descended to the habitat for familiarization with the operations and for. medical tests. The aquanauts’ ascent was delayed about two hours when Commander Carpenter, scheduled to remain below with Team Two, was stung on the index finger of his left hand by a poisonous scorpion fish. After medical treatment, it was decided that he could safely remain below for the full 30 days as planned. Finally, the nine aquanauts swam free from the habitat to the personnel transfer capsule; the bottom hatch was closed; and the chamber raised to the surface and mated to the deck decompression chamber on the Berkone. After all the personnel were transferred to the decompression chamber, the personnel transfer capsule was lowered back to the bottom, and the remaining six men of Team Two descended to the bottom and entered the habitat.
Productive work of Team Two was started sooner, since many of the tasks that Team One had to accomplish to occupy the habitat did not have to be repeated. A major portion of Team Two’s efforts were devoted to physiological, biological, and other scientific experiments within the habitat. In one experiment, seen above, the effect of a pressurized^ helium-rich atmosphere on plant growth was studied■
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earn Two conducted tests with Tuffy (top photo- S^ph), a porpoise trained to respond to sound sig- a s> to determine whether such an animal could be SeJul to men in the sea. At first the porpoise did not sPond as expected, probably because of the new groundings and noise of the surface support ship, owever, he later performed beautifully by making overal dives to 205 feet, delivering mail attached to !ls harness, and carrying a guideline to a diver in- ntionally signalling that he was in need of assis- ^nce- On his longest dive, Tuffy stayed below for U\ lnutes. Sea lions in the area (bottom photograph) ere attracted to the habitat by the abundance of sh surrounding it. After gorging themselves, they amuse themselves by peering in through the ass ports at the aquanauts.
Electrically heated wet suits were tested by Team Two. Heated by AC umbilical cords connected to the habitat or by waist-mounted batterypacks, the suits in general extended the swimmers’ endurance from one hour to about two hours in the 50-degree water. However, a number of modifications will be required to make them completely successful.
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While Teams One and Two were on the bottom, helium and oxygen for the swimmers’ SCUBA tanks had to be replenished on the surface, and a great deal of time was expended in transferring the tanks between the Sealab and the surface. During Team Three’s stay, a high-pressure supply hose was sent down, and the team was able to charge its own bottles within the habitat.
Team Two came up in the personnel transfer capsule on 26 September without incident, and on the same day, the third and last team descended for its 15- day stay. Team Three, headed by Master Chief Torpedoman Robert Sheats, U. S. Navy, comprised one of the most experienced groups of divers in the Navy, and a primary mission of the team was to perform salvage experiments. In one test of a new salvage concept, an aircraft fuselage was filled with buoyant foam generated on the bottom, and raised. In another, a lifting pad and a plate patch were attached to a one-inch-thick, high-yield, steel plate simulating a portion of a submarine hull, and torque free and explosive tools were tested. The lifting capability of a new type of inflatable pontoon was also tested. All of these tasks were performed expeditiously and were considered successful.
Normally the aquanauts were limited in range of depth to one atmosphere above or below their average depth, that is, to depths between about 170 and 230 feet. Team Three, however, received permission for excursions into the Scripps Canyon to a depth of 300 feet. One team member is seen above, collecting a sample from a ledge near the 300-foot level, on the first such dive. (Swimmers from Team Two had earlier descended to the brink of the canyon, a depth of 266 feet.) The greatest danger to Sealab II swimmers was that of accidentally being forced to the surface, which, in their saturated state would be fatal. Another danger was that of becoming lost and running out of breathing gases. Perpetual near darkness, poor visibility, and the absence of diver communications with the habitat and the surface contributed to this problem. Within the habitat itself, atmospheric contamination, flooding, and power and equipment failure were potential hazards.
During its last three days on the bottom, Team Three prepared the habitat for its return to the surface, including the attachment of air salvage hoses and lines, and installation of pressure-proof internal port covers. Finally, on 10 October the team entered the personnel transfer capsule and was hoisted to the surface (above). As soon as the team members were safely in the decompression chamber, work was started on recovery of the habitat, and it was successfully refloated the following day.
With the aquanauts inside, pressure in the deck decompression chamber was slowly reduced from 100 pounds per square inch, absolute, to normal atmospheric pressure of lf.7 pounds per square inch. Between 31 and 35 hours were required for decompression, to allow gases to escape from the divers’ saturated body tissues without harming them. Chief Sheats of Team Three had to remain in the chamber for an additional 12 hours for treatment of a case of bends, but all other personnel of the three teams decompressed without incident. During their f5 days on the bottom, the three teams had logged more than 300 man-hours of work outside the habitat. While the long-term effects of their dives cannot be easily predicted, exhaustive tests conducted at the San Diego Naval Hospital upon their return from Sea- lab II disclosed no immediate discernible physical or psychological ill-effects in any of the men.
J'he Sealab II project demonstrated that man can •?*e and perform productive work under the sea • 0r long periods of time. The cost of the project, dhout l .5 million dollars, was modest in view of the knowledge gained. The undersea world has great economic and scientific potential, but the frontiers of ‘his vast world have barely been dented. As man goes deeper and deeper, the problems will compound, but ‘hey will be solved if appropriate effort is applied. : he rewards of the conquest can only be guessed at, hut they will be enormous.
Commander Robert H. Smith, Jr., U. S. Navy, receives a gold medal, a life membership in the Naval Institute, and a cash award of $1,500 for his prize-winning essay,
“The Submarine’s Long Shadow,” entered in the 1966 General Prize Essay Contest.
More important, his essay was published in the Proceedings and mailed to more than 60,000 members.
If you have something to say to a professional Navy audience, plan your essay now.
Enter the 1967 General Prize Essay Contest. (Deadline 1 November 1966)
For complete information write the Secretary-Treasurer,
U. S. Naval Institute,
Annapolis, Maryland 21402.