22.2.1. Methods of investigations 335




The turning point in German submarine design was reached in the summer of 1943. At this time, allied countermeasures were holding the German submarine fleet in check. Leading submarine designers and engineers from all main building yards were conscripted in late 1943 and ordered to the little town of Blankenburg in the Harz mountains where the central design agency for the Type XXI program was established under the Speer Ministry. The solution proposed was the design of a highly maneuverable, high-speed vessel which could remain submerged most of the time and which could operate at greater depths than previous conventional submarines. The problem was attacked with characteristic energy, and the result was a revolution in submarine design philosophy. The most interesting example of the new trend is the well-known Type XXI.

The vessel had a large battery capacity (372 cells, 11,300 ampere-hours). The hull was designed for a depth of 120 meters, and one of these vessels had submerged to a depth of 190 meters under full control. Type XXI was the first German submarine to have 6 bow tubes with a capacity of 20 torpedoes.

Although 119 of these boats were delivered to the assembly yards, none got out on war patrol.

A still later type, the Type XXVI, was the ultimate in German submarine design, intended for continuous submerged operation, which was to be a vessel of approximately 775 tons, 177 feet in length. Walter, a submarine design engineer, at this time was able to speed up the acceptance of his hydrogen peroxide or Ingolin submarine. He had experimented on the use of hydrogen peroxides since 1935 and had built and operated an 80-ton experimental model. It performed in accordance with his design and realized some 25 knots submerged speed. Later he built five operational models of 380 tons surface displacement. These never had a war patrol because there was never enough peroxide to permit them to so operate.

  The design of the Type XXVI included in addition to the Walter Turbine, three other modes of propulsion; namely, a diesel engine of 1,200 horsepower, and an electric motor of 580 horsepower, and a creeping motor of 35 horsepower which drove the main shaft through a multiple system of V belts. These vessels were expected to make about 25 knots submerged on the turbine, and 10 on the electric motor; while for the diesel power on the surface the speed was to be 14 knots.

In general, the new concept of a submarine was a vessel which could remain submerged for a long period of time without radical changes in the design of the ventilation, air-purification, or oxygen-renewal systems. The use of the snorkel at periodic intervals for charging batteries provided sufficient air renewal and ventilation. In fact, the total blower capacity in all German submarines, including the newest types, is relatively low; but the operational doctrine was such as to eliminate any demand for greater blower capacity. This should have affected the comfort of the crews, but apparently this condition was cheerfully accepted by them as necessary to permit safe operation with a minimum use of fuel.

In earlier German submarines, no air conditioning was installed, and the large majority of operational submarines during the war had no means of cooling or drying the air in the vessel. In the Type XXI, an air-cooling and dehumidifying system was provided which could be used also as a heating system.

Plans for future submarines in the United States Navy indicate that the present fleet-type is indeed obsolete, and to replace the vessels which made such an enviable record in World War II, there will be items of conversion and items of new construction. The conversions consist of altering present fleet-type submarines in order to obtain additional submerged speed and projection by snorkel for diesel engine propulsion and battery charging when submerged.


The snorkel consists essentially of a 15-inch intake and a 15-inch exhaust tube, which are capable together of being raised or lowered hydraulically and will permit the running of the diesel engines while submerged. Thus, the batteries may be charged or the engines may be used for prolonged periods of submerged propulsion with only a few feet of the uppermost portion of the snorkel intake tube exposed above the surface. A valve, commonly called the head valve, located on the top of the snorkel intake tube, closes when submerged due to temporary loss of depth control, heavy seas, emergency deep dives, etc., and reopens on subsequent reexposure to the atmosphere. During the period in which the valve is closed, air supply for the diesel engine is drawn from the approximately 35,000 cubic feet volume within the ship, at a rate varying from 5,600 cubic feet per minute to 12,000 cubic feet per minute, depending upon the revolutions per minute and whether one or two engines _are running. This utilization of the air within the ship for engine combustion results in considerable reduction in pressure within the boat, and is analogous to ascents by planes or other means to relatively high altitudes. Engine exhaust gases are discharged to the outside via the snorkel exhaust tube. Thus, the exhaust outlet is submerged under a varying column of water, depending upon depth.

New construction's goal is primarily production and perfection of an American version of the Type XXI, with the ultimate goal of the true submarine with all operations submerged and being capable of a high submerged speed. Generally speaking, present-type submarines may be described as surface vessels capable of submerging, while the new vessel's description is more aptly a submerged vessel which rarely operates on the surface.

The medical problems to be encountered in these new ships will not be unlike those current in the present fleet-type vessels, with some notable additions. Inasmuch as there appears to be some correlation between personnel casualties and the number of days submerged, it does not seem unreasonable to expect a multiplication of all the present submarine ills. In addition, ventilation for engine combustion and compartment replacement by snorkel will probably produce some difficulties.

Ear damage is the main pathology resulting

  from experiments in loss of depth control. Aside from the purely physical ear effects, it must be realized that there is no way, at present, in which to abolish the entire crew's constant awareness of the changing ambient pressure, incident to closure of the snorkel head valve, when the water level approaches the intake. Instead of the ventilation period heretofore accomplished on the surface, being one of comparative calm except as heightened by danger of detection by aircraft and surface vessels, there is now an added tension factor, possessed of a constant reminder of the ear's sensitivity to pressure change. It is possible that personnel will accustom themselves to these changes but there remains the banging noise incident to head valve closure as a warning sign. It seems pertinent to emphasize that ear effects are not manifest during the period of closure of the snorkel head valve and accomplishment of the lowered barometric pressure, but rather appear when the snorkel emerges and pressure increases toward the former surface level. If return to snorkel depth, subsequent to loss of depth control, is sudden, as sometimes occurs because of overcompensation, those who cannot equalize because of eustachian closure will experience considerable pain and ear damage. Experience teaches that the opening of the inner end of the eustachian tubes in the presence of decreasing barometric pressure is an automatic venting process, while the opening of these tubes in the presence of increasing barometric pressure is a conscious process requiring voluntary effort on the part of the individual. Experimentally, there is confirmation by increased ear pathology among those asleep during simulated loss of depth control. Production of submarine insomniacs would destroy the last avenue of daily escape from the monotony of continued submarine residence. The implications are evident.

Experiences of the last war indicated the need for refitting of both men and machinery after 60 days. The incidence of personnel and engineering casualties increased sharply if war patrols were continued for more than 2 months. It must be remembered that such incidence occurred only when the daylight hours were spent submerged. Therefore, it does not appear unreasonable to expect that the new vessels, with continued submergence, may produce some shortening of effective patrol duration.


In the past, carbon dioxide and oxygen percentages, when a submarine is submerged, have not been matters of too great concern; at least they have not been factors limiting endurance-possibly due to the efficient ventilation accomplished during the night surface operation periods. The new types, minus the opportunity for surface-compartment air renewal, may produce unacceptable percentages in both oxygen and carbon dioxide. Important in this connection is the fact that the lowered barometric pressure, occurring in actual snorkel experiments in loss of depth control, has been of the order of 18 inches of mercury, equivalent to an altitude of about 12,000 feet. Should lowered oxygen percentages be existent during loss of depth control, oxygen partial pressure incompatible with consciousness might be encountered. It suffices that the new vessels will present such a mass of complicated machinery that rigid education will be required of all hands for normal navigational and attack operations. No time will be available to devote to the status of these gases. The need for continuous recording methods and automatic countermeasures initiation is apparent.

The diseases peculiar to submarines consist of colds, constipation, skin diseases, and various physical complaints of neurogenic or psychic origin. (See chapter 20.) The appearance of this quartet of maladies appears likely to continue unabated or to be increased in the new designs. The submarine medical officer, therefore, is concerned chiefly with preventive medicine, and his field of greatest usefulness is in the selection of personnel. It is not only mandatory that crews of submarines be composed of personnel who are free of actual and potential disease, but also that they possess a high degree of natural or acquired disease immunity. Probably more important is the necessity for a stable or even phlegmatic psyche. Reasons underlying these standards are obvious: (1) the limited facilities for treatment aboard the submarine itself; (2) the inability to request medical aid for fear of disclosing the vessel's location; (3) the usually remote location of patrol areas and thus remoteness from treatment centers, and the desirability of not having the vessel abandon its mission to make the long return journey to seek medical assistance for the sick; (4) the need for each crew member to be physically self-sufficient and to be able to perform his allotted tasks without reliefs, which cannot be carried; (5)

  the need for stable alert personnel to perform highly technical tasks during high-tension episodes; (6) the very nature of submarine residence in its capacity to propagate and disseminate illness, wherein a focus of a single diseased person is a most undesirable factor.

Training and facilities for escape (see chapter 21) are still a necessity for submersible vessels because, in spite of present perfection, accidents involving trapped live personnel are still a possibility and were an actuality as late as 1944, when one of our own vessels was sunk by erratic performances of its ordnance weapons. Submarine escape is divided into two types: (1) individual escape, consisting of rising through the water from a submerged hulk by use of the submarine "lung" or by free escape with no breathing Apparatus; and (2) collective escape with the rescue chamber or bell. Submarine medical officers are vitally concerned with escape training, especially free escape or escape with the Momsen lung, principally because of the respiratory physiology involved and the nature of the resulting accidents. In fact, submarine escape training methods are considered a valuable adjunct in personnel selection and are utilized as such. Men's reactions underwater provide visible indices to their stability in stress situations.

During war patrols there is no dumping of garbage and sewage during the daylight hours or during any period when any craft are likely to be in the immediate vicinity for fear of disclosing the submarine's location. Such materials must be stowed for later disposal in sanitary tanks, along with the water from the clothes washing machine. This waste accumulation, subjected to agitation from the ship's motion, is productive of offensive odors which permeate the boat during submerged periods. Vapors from cooking, hydrocarbon vaporization from the machinery and bilges, together with body odors, plus the factor of age of accumulation, accentuate the degree of offensiveness. These odors represent a factor thought to be distinctly detrimental to morale. Successful countermeasures are now imminent. At present they remain as a submarine problem in the submarine medical officer's field.

The submarine medical officer's role in procurement of select personnel appears to remain as his most vital function. (See chapter 19.) The effort expended toward personnel selection seems to have


been warranted as may be attested by the fact that (1) Japanese submarine personnel, without comparable selection, exhibited crews with the following disease incidence: tuberculosis 10 percent; skin disease 95 percent; intestinal parasites 80 percent; Neisser infection 30 percent; syphilis   5 percent; typhus 1 percent. (2) In a force that represented approximately 1 percent of our naval strength, and which accomplished the sinking of more than 60 percent of the ships sunk by all forces of all the United Nations, there occurred an attrition rate of less than 1 percent.
The advent of atomic propulsion for submarines has posed many new medical problems and added to the multiple existing projects which required immediate answers. Most vital and of major concern is that of atmospheric vitilation. The solution of this subject has been a matter of continuous study since 1901, when the first experiment was conducted by submerging a submarine alongside a dock for 24 hours in order to determine the quantity of oxygen consumed by its occupants.

Albeit much scientific knowledge has been acquired in the interim concerning oxygen consumption, and related facets, the development of nuclear energy for submarine propulsion has created additional interest. Consequently this subject is currently being attacked with renewed interest.

22.2.1. Methods of investigations.

With the knowledge that greatly prolonged periods of submergence were anticipated in the atomic submarine, considerable attention was directed to the study of physiological changes which occur when air containing elevated concentrations of carbon dioxide is inspired. An exhaustive study of this problem has recently been undertaken by the United States Naval Medical Research Laboratory at New London, Conn.

Data from both acute and chronic exposures had to be gathered in order to construct a predictive time-concentration toxicity curve for carbon dioxide. Such information has partially been supplied from three primary sources: (1) recent laboratory studies which prescribed both short and relatively long exposure periods to varying carbon dioxide percentages, figures 154 and 155; (2) past operational experiences where prolonged, but interrupted, exposures were encountered during war patrols of both American and German submarines and, (3) a recent research project, known as "Operation Hideout," in which a considerably prolonged and uninterrupted exposure was simulated aboard a partially activated submarine.

  The acute effects were investigated by exposing 60 human volunteers to carbon dioxide concentrations of 1.5, 3.3, 5.4, and 7.5 percent in air over a a period of 15 minutes. Each exposure was preceded and followed by an air-breathing period of equal duration for control observations. Measurement of the respiratory rates, tidal volumes, respiratory minute volume, alveolar carbon dioxide tensions, cardiovascular and neuromuscular responses, basal oxygen metabolism and blood chemistry levels, permitted the establishment of an adequate quantitative relationship of these variables during the steady state and an evaluation of the transitory response to carbon dioxide.

All of the above concentrations caused an increase in the respiratory minute volume due mainly to increased tidal volumes. Decreases in basal oxygen consumption and blood sugar level occurred with concentrations over 3 percent. The pulse, blood pressure and respiratory rates increased significantly only with concentrations above 5 percent.

In contrast to these stimulatory effects of carbon dioxide on respiration, circulation and the autonomic systems, depressive effects in the central nervous system were also produced. These were demonstrated by a decrease in the flicker fusion frequencies as measured with the Krasno-Ivy meter and by changes in the EEG pattern. The latter revealed that the time required to produce blocking of the alpha rhythm by a light stimulus increased in direct proportion to increasing carbon dioxide concentrations.

These findings indicate depressed activity of the cerebral cortical centers with simultaneous stimulation of lower brain stem centers, the autonomic nervous system and the endocrine system.

In regard to prolonged exposure to carbon dioxide, laboratory studies have shown that exposure to 2.5-3.0 percent over a period of 3 to 6 days produced depressive effects on the central nervous system following a transient period of


Supine patient with three medical staff in attendance.
Figure 154.-Obtaining cardiorespiratory data during short term inhalation exposures to high CO2 mixtures.
excitation. These depressive effects usually became apparent after 3 or 4 days and were indicated by a reduced sensitivity of the respiratory center to carbon dioxide, an increased chronaxia, and a decrease of the blocking effect of light stimuli on EEG alpha waves. The initial period of excitation, manifested subjectively by euphoric symptoms and a feeling of improved efficiency, is not unlike that produced by mild anaesthetic agents and may in effect be due to a depression of the higher brain centers. Operational experience during American and particularly German submarine war patrols disclosed that similar mental effects were produced by intermittent, but successive, exposures to high carbon dioxide concentrations. The coexisting depletion of oxygen may possibly have had an augmentative effect on these mental reactions.   The regulation of the acid base balance during exposure to 3 percent carbon dioxide shows two distinct phases. In the first or acute phase, lasting up to 3 days, the normal plasma pH is maintained through increases in respiratory ventilation and renal excretion of bicarbonate. In the second or chronic phase, the blood pH is maintained by gradual shifts of electrolytes while hyperventilation and bicarbonate excretion are decreased. The increase of plasma alkali, as indicated by a change of the carbon dioxide dissociation curve, is explained by renal retention of sodium and by shifts in the distribution of chloride. It is interesting to note that the depressive effects of 3 percent carbon dioxide upon the nervous system appear simultaneously with these adaptive changes of the blood. Body pH and the homeostasis of the internal environment are maintained, but the


Supine patient with lots of equipment attached.
Figure 155.-Obtaining electrocardiographic and electroencephalographic data during short term inhalation exposures to high CO2 mixtures.
organism pays for it with a decreased sensitivity of the nervous system.

The alveolar carbon dioxide tension gradually increases during prolonged exposure to 3 percent carbon dioxide and after a period of 4 to 6 days reaches a level which corresponds with that found during short exposures to 5 percent carbon dioxide. This level appears to be the threshold concentration for depressive effects upon the central nervous system.

Coincident with these adaptive changes of the blood and alveolar carbon dioxide are certain changes which occur within the endocrine system. Data from experiments on guinea pigs and dogs indicate that during prolonged exposure to 3 percent carbon dioxide a hypersecretion of adrenalin is followed by a period of hyposecretion. Histologic

  changes, consistent with a phase of hyperactivity followed by hypoactivity, were also found in the adrenal cortex and in the basophilic cells of the pituitary gland. Thyroid activity in these animals also appeared to decrease. Apparently chronic exposure to 3 percent carbon dioxide initially stimulates the autonomic nervous system and certain endocrine glands but eventually leads them to exhaustion. This final exhaustion phase closely simulates the depression syndrome produced when high carbon dioxide concentrations (e. g. 30%) are breathed for brief exposure periods.

When the rigorous requirements for the SSN were made known, it soon became apparent that past research and operational experience did not begin to solve the many pressing problems. Of prime concern was an answer to the question-


what is the maximum allowable concentration of carbon dioxide for extended operation? How large and how efficient would the carbon dioxide removing machinery of the SSN have to be? How much carbon dioxide could such machinery leave unabsorbed and yet be tolerable by the crew? What about other vital human factors? How   long could men be incarcerated without exhibiting signs of mental or physical breakdown? These questions led to the undertaking of a large-scale study in submarine medicine early in 1953 at the Medical Research Laboratory, United States Naval Submarine Base, New London, Conn.
In this experiment one volunteer medical officer and 22 enlisted men were confined aboard a partially activated fleet type submarine for a period of 2 months, figure 156. Additional participants included 60 guinea pigs and 100 white rats. The basic experimental design of "Operation Hideout," consisted of measuring   human performance in three dimensions. These were psychomotor performance, measurement of physiological functions and psychiatric and sociological studies. The latter studies were included in order to make observations on such variables as mood swings, social adjustment and interpersonal relationships which might possibly color
Two crew members reviewing some data.
Figure 156.-Operation hideout-reviewing the 2-month outline of daily physiological, psychomotor and psychometric tests.


Drawing a finger blood sample.
Figure 157.-Operation hideout-obtaining blood samples.
the results obtained in the first two areas. Specific details cannot be discussed here but some of the general considerations of the experiment will be presented.

Out of some 200 actual volunteers, the group was scaled down to 40 by selecting only the most physically fit men. The final 22 men were chosen on the basis of temperament and background. It was intended to seek men of a variety of ages, home state, and skills, and to select some with fiery natures as well as others with placid dispositions. Only two men, besides the medical officer, had served before on submarines. Four others

  had just completed training at the Submarine School. The rest were nonsubmariners from other branches of the service.

The volunteers were first given an exhaustive physical, psychiatric and psychological assessment. Following this they were practiced on various psychomotor tests and base line data was obtained for the physiological measurements. On 19 January 1953 they were placed aboard the U.S.S. Haddock and after a brief shakedown period on air, the desired carbon dioxide concentration was maintained. The exposure was continued until shortly prior to their release when


Nine sailors and one doctor gathered in the control room for testing.
Figure 158.-Operation hideout-testing auditory pitch discrimination.
fresh air replaced the carbon dioxide laden atmosphere. On 19 March they were released from the Haddock, and after a 10-day rest period, all of the studies carried out on board the Haddock were repeated.

The general plan consisted of taking physiological measurements in the mornings and psychological tests in the afternoons, 5 days each week. Pulse, temperature, blood pressure and urinalysis from each subject were recorded daily. Respiratory tests were conducted on each group of 10 men on alternate days. While in the basal state, these consisted of measuring tidal and minute volumes, vital capacity, alveolar carbon dioxide levels and tolerance capabilities to higher carbon dioxide concentrations. Periodic blood samples were drawn for chemical and cytological studies, figure 157. EEG's were recorded and the effects of

  light stimuli upon the alpha waves were measured. Many EEG's were recorded during complete sleep cycles. Circulatory efficiency tests were performed in the late morning. Particular attention was focused upon whether stimulatory or depressive effects took place within the central nervous system, the respiratory center or the circulatory system and what adaptive changes took place in the blood and kidney functions.

The psychological and psychomotor tests included measurements of body sway, neuromuscular coordination and reflexes, visual perception, auditory pitch discrimination, figure 158, and manual dexterity and alertness tests, figures 159 and 160. They were administered not only to evaluate any adverse effects from carbon dioxide but also to analyze individual reactions to the long period of confinement.


Performing reaction tests.
Figure 159.-Operation hideout-observing psychomotor response.
The psychiatric studies of "Operation Hideout" were necessarily limited by the primary mission of the experiment. The methodology consisted of a pre-experiment assessment, daily written comments by each volunteer with no attempt to structure or channel the material, casual conversation and observation with various volunteers by the psychiatrist on daily visits aboard the submarine, and a structured questionnaire of four questions at the termination of the incarceration period. In addition, the volunteers were asked to complete a self-rating scale in several word association tests during the course of the experiment.

The psychiatric assessment revealed that the volunteers possessed personalities of considerable variety. These ranged from compulsive and anxiety patterns to calm, easy-going, phlegmatic types; from inadequate and immature youths to realistic, ambitious, mature individuals; from below average to superior intellectual individuals; and from apparently well adjusted persons to

  individuals who displayed obvious signs of deep emotional conflict.

The motivation for volunteering was an important clue to certain personality needs. Those

Sailor with doctor.

Figure 160.-Operation hideout-recording psychomotor data.


with feelings of inadequacy, insecurity or unsatisfied achievement offered their services in order to identify themselves with something big or important. On the other hand, the more materialistic and practical men volunteered to avoid more disagreeable duty such as mess cooking or deck swabbing. Still others with a more realistic consideration of the problem felt that the undertaking was worth any personal inconvenience for the knowledge they acquired and the great service   that they rendered to the Navy and their country. A most interesting observation was that this group of strangers with relatively few characteristics and interests in common, molded themselves into a well-integrated and loyal team. At the conclusion of the study half of the volunteers stated that they would be willing to repeat the experiment and none of them expressed any regrets over having volunteered.
It must be recognized that the consistent and prolonged effectiveness of the crew of any submarine is a direct reflection of the state of morale of the group, and morale is a product of many components, the environment being not the least. All possible measures are being taken by the doctor and the engineer to lessen personal anxiety and irritability. Men can be strained to the breaking point when they are confined in close quarters where day and night have no meaning, where there is no sense of progressive motion and where only the vessel's log will tell them whether they are under Arctic ice or in the warmest waters of the South Pacific.

The interior of the atomic submarine will be pleasant and habitable. Every human effort will be exerted to that end. Air conditioning, heating equipment, special lighting, color schemes, and interior design for eye-resting comfort will be incorporated in the general plan. Comfortable berthing and messing spaces, the best food the Navy knows how to buy and prepare will be

  provided along with adequate bathing and toilet facilities. A small library and writing space, tables for small space games, a motion picture outfit, phonographs with a large collection of records, and a table always set with tasty snack items for between meals munching, a coffee urn steaming around the clock will be a part of the overall scheme designed to improve the environments of the submarines.

The personnel assessment and selection program assumes more importance and is being pursued with greater impetus so that it will be possible to pick nuclear submariners who have what it takes with something more to spare. They must be physically fit, emotionally mature, temperamentally stable and above average in intelligence and aptitude. They must possess the necessary stamina to live for long periods in crowded quarters with little privacy. They must be able to withstand the stress of monotony and boredom, yet capable of enduring the intense excitement which attends contact with the enemy.


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