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.
332
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.
333
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
334
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.
22.2. MEDICAL CONSIDERATIONS OF ATOMIC SUBMARINES
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
335
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
336
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-
337
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.
22.3. OPERATION HIDEOUT EXPERIMENT
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
Figure 156.-Operation hideout-reviewing the 2-month outline of daily physiological, psychomotor and psychometric tests.
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
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.
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
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.
22.4. CONCLUSIONS
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.
