Hot pants: Heated garments in works for divers, sailors

Whether it'is divers at dangerous depths, aircrews at high altitudes or Marines in cold, wet climes, just about every old salt has a story about battling bitter chill.

Electrically heated thermal undergarments that maintain core temperatures in the most extreme conditions are in the works. Funded by the Office of Naval Research and developed by the Underwater Systems Development and Acquisition Branch at Naval Surface Warfare Center, Panama City Division, in Florida,Fla., the effort is focused on the diving community, but its headchief designer sees it them as an amphibious-based garment for use in and out of water.

Staying warm is the name of the game, but the go​al is more than comfort; this is about resiliency and mental acuity, said Klose, a submarinerbubblehead by trade who has worked on underwater mobility projects for 25 years. A suit that maintains regular body temperature means the body doesn't need to expend energy to stay warm. In addition, your brain is much like your fingers and toes, the brain : It doesn't work well in frigid temperatures. Its ability to make decisions diminishes as it gets you get colder, and confusion — deadly in extreme conditions — can quickly set in quickly.

In seeking a solution, Klose first looked at heating fibers available in the commercialprivate industry, but none met the energy efficiency or safety levels required by naval standards. He was, however, intrigued by cCarbon nNano-cCore fibers produced by Coliant Corp.ration, a company that manufactures heated motorcycle jacket liners. An alliance was forged, made and design modifications followed over the next 18 months. The team put its prototype polypropylene long underwear to the test last fall and reported its findings in late December — and initial reports were good.

Unmanned testing measured heat characteristics at various voltages and found no hot spots. The latter has been a point of contention with electrically -heated diver thermal protection suits in the past, as hot spots tend to burn the diver. Manned testing in a 40-degree cold water tank followed at the University of Montana's Center for Work Physiology and Exercise Metabolism. That temperature was picked because 95 percent of diving operations are in waters 40 degrees and warmer, said Klose, who was among more than a one dozen subjects who took the plunge.

For a sailor wearing a normal wetsuit in 40-degree water, Hhypothermia — a loss of core body temperature that can quickly lead to death — would take about 20 minutes in those water temperatures in a normal wetsuit. But Klose said he "was perfectly comfortable," sitting in the tank. Test results showed the subjects expended no extra energy to maintain core temperatures. In fact, the team found its suits used "a lot less power than other systems have used before" and still maintained core temperatures in that extreme environment.

But don't expect to find the suit in your dive locker run out to the exchange just yet. Klose's team must next work with Naval Sea Systems Command to transition this technology from a proof of concept to a program of record. That is not an easy task; the path is often referred to as "the valley of death." Klose will use the coming months to refine the product and design mission-specific prototype garments to better convince the bean counters and decision-makers.

Indeed, this is not a matter of throwing in a couple of AADuracells. Batteries that power this type of gear hold significant energy contained in small spaces, and that makes the power packs potentially dangerous and heavy — two attributes Klose is unwilling to accept.