When Your Dry Suit Will Double as Day Wear

Coming soon: forget that change of clothes .

If there’s one thing James Bond didn’t have, it was decent amphibious — wet and dry — clothing. Just think of all the times he clambered out of water clad in dive gear, only for the bad guys to get a head start while he struggled to get into dry clothes.

Now the US Army’s Soldier and Biological Chemical Command Lab in Natick, Mass., has come up with an answer: a dry suit you can wear comfortably out of the water. The amphibious suit is designed so US Navy SEALs can get out of the water ready for action in lightweight garb.

In the water, the dry suit performs like any other, keeping the wearer warm by preventing water from reaching the skin. But once out of the water, the structure of its novel three-layer membrane changes to let perspiration escape, so the wearer doesn’t become overheated and have to change into dry clothes.

Navy SEALs are now testing the suit for general comfort and warmth in a range of water temperatures and pressures. It will be at least a couple of years before the suit is ready for use, says Quoc Truong, program manager at the Natick lab, but after that it won’t be long before it finds its way into civilian life.

“Compared to a dry suit, it will be a bit heavier because we wanted to use a durable fabric,” says Truong. “But it’s still very light.” And SEALs won’t have to lug around an extra set of dry clothes.

So how does it work? The suit consists of a polyurethane-based shapem emory polymer layer, sandwiched between a laminated low-drag stretchable outer fabric and a heat reflective insulation layer on the inside. The transition temperature of the polymer membrane is predetermined; between 55-65 degrees F it has a dense molecular structure that stops water molecules from passing through it. When the temperature rises to between 65 and 80 degrees F, the material softens and becomes more amorphous, so sweat molecules can pass through it.

The suit is also impervious to urine, says Truong. On land, wearers can relieve themselves by way of a zipped opening that reaches from the shoulder to the groin, but in the water, SEALs would have no alternative but to pee in their suit. Truong is confident that the acid in urine will not rot the new suit’s material and hamper the diver’s activities.

New Scientist, March 31, 2001.