Passive methods of protecting a diver from cold exposures are constantly being sought as alternatives to active heating systems. All passive thermal protection techniques share one common advantage over their active heating counterparts; they have no requirement for energy storage or energy distribution. This advantage tends to make passive protection less complex and usually less expensive. Unfortunately in severe cold water, passive systems have customarily required divers to use thick, layered insulating garments worn beneath waterproof diving suits to reduce the loss of body heat to the surrounding cold water. These suits tend to be excessively bulky — inhibiting diver mobility; inherently buoyant — requiring 40–60 pounds of lead weights to make the diver neutrally buoyant; difficult to keep waterproof — an uncertainty that could fatally reduce the diver’s thermal protection during long duration missions; and only minimally effective in protecting the divers’ extremities. Even the best conventional drysuits have been found to be inadequate to meet the full requirements for long duration missions in near freezing waters.
The objective of the research reported in this paper has been to provide the diving community with improvements in thermal protection for long duration, cold water missions. The unconventional approach proposed here, the use of liquids as an insulating medium for divers’ suits, shows promise as a means of significantly surpassing the performance, and acceptable durations, of conventional drysuits. Laboratory testing of conceptual insulating concepts are reported.