To assist design of adequate protective clothing, mathematical model of man's thermoregulatory system has been developed so that body thermal responses under immersed conditions can be predicted accurately. Experimental data encompassed wide range of water temperatures, protective clothing, breathing-gas mixtures, and durations of immersion

Montgomery, L. D.

English

NASA Technical Reports Server

February1975	 B75-10029 
NASA TECH BRIEF 
Ames Research Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Analytic Model for Assessing Thermal
- Performance of SCUBA Divers 
As explorations of the oceans continue, it may be 
necessary for man to dive to greater depths and stay 
under water for longer periods of time. Diver per-
formance is in large measure limited by the lack of 
adequate thermal protection as required for all com-
binations of diver activity, depth and duration of 
dive, and ambient water temperatures. To assist the 
design of adequate protective clothing, a mathemat-
ical model of man's thermoregulatory system has 
been developed so that body thermal responses under 
immersed conditions can be predicted accurately. 
The biothermal model is divided into the physical-
controlled system and the dynamic-controlling system. 
Two types of experimental data were used to sub-
stantiate the analytical model: immersed-to-the-neck, 
seminude subjects in cold-to-temperate water and 
immersed-to-the-neck, "wet-suit" subjects in cold 
water. The experimental data encompassed a wide 
range of water temperatures, protective clothing, 
breathing-gas mixtures, and durations of immersion. 
From the law of propagation of errors, influence 
coefficients have been derived for 16 parameters that 
affect the skin and rectal temperatures. These influ-
ence coefficients were integrated to obtain four general 
influence equations for the parameters considered 
upon the temperatures at rectum, trunk, fingers, and 
toes. It has been demonstrated that the equations
may be used to predict rectal and skin temperatures 
for various dive conditions represented by small 
parameter changes around the standard set of values. 
The parameters that can be controlled by appro-
priate engineering design to improve the underwater 
performance of man in cold water have been identi-
fied; other parameters have been shown to be ineffec-
tive in preventing rapid cooling of the diver. By use 
of the various influence coefficients, equations, and 
the analytical model, any proposed engineering design 
can be evaluated without need to construct expensive 
systems or to undertake testing programs with human 
beings. The model may also be used to assess the 
endurance and performance of a diver in cold water. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: TSP 75-10029 
,Source: Leslie D. Montgomery
Ames Research Center 
(ARC-10927) 
Category 09 
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Analytic model for assessing thermal performance of SCUBA divers

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