Home|Glossary|Links|Journal|Maps

 

Gearing Up

It's cold. It's dark. There's only one way out. Diving in the perennially ice-covered lakes of the Dry Valleys presents a lot of challenges. So how did research divers Ian Hawes, Donna Sutherland, and Maria Uhle do it? They started by layering up.

First they put on a set of polypropylene long underwear. On top of this, they wore a jumpsuit made of synthetic down and known as Weasel Extreme.

"Synthetic down is the same kind of material you'd find in a cold weather sleeping bag", explains Maria, a professor at the University of Tennessee-Knoxville.

A waterproof membrane dry suit went on top of the Weasel Wear. Although dry suits come in different designs, a typical one will have special seals on the wrists and neck to keep water out and a zipper across the back going from shoulder to shoulder to provide the entry way into and out of the suit. Another person had to help the divers zip up.

On their hands, the divers wore polypropylene glove liners and pulled on rubber gloves that, like the dry suit, had seals to keep water out. Some of the divers also wore booties on top of their suit to give their feet extra insulation and padding. Fins were a must since they helped the divers move more quickly through the water.

Perhaps one of the most specialized parts of the Dry Valleys' dive team equipment, however, was the team's headgear. Recreational divers tend to carry their air around with them in scuba tanks on their back, and they breathe into and out of a regulator they keep in their mouths. Their air supply is therefore limited, underwater communication is difficult, and underwater to surface communication is impossible.

The dive team in contrast made use of band masks. This is a mask that covers the whole of your face rather than just your nose and eyes like a normal dive mask, explains Donna, a researcher with New Zealand's National Institute of Water and Atmospheric Research (NIWAR). It consists of a steel and fiberglass frame that holds a plastic front glass. On the inside of this front glass is a rubber gasket that forms a watertight seal against the diver's face, enclosing his or her eyes, nose, and mouth. Air enters the mask through a valve on the side. The mask is held to the diver's face by a rubber hood. "Band masks are warmer than normal dive masks and allow quite sophisticated air and communications equipment to be incorporated", says Ian, who like Donna is a researcher with NIWAR. For the Dry Valleys dives, an air tube linked the mask to an air supply on the surface and gave the divers a virtually inexhaustible supply of air. A microphone, earphone, and communications wire in the air tube allowed the divers to actually talk underwater with people on top of the ice. "Water does slowly seep into the bank masks", notes Ian, "but it can be blown out and does not pose an undue cold risk".

Donna and Maria help Ian get his dive hood on

Maria with her band mask and hood on

A last piece of equipment that the divers needed may seem counterintuitive at first. If a diver dressed in all the aforementioned gear lowered him or herself into a dive hole, he or she wouldn't be able to dive. That's because the person would just float. Although the gear adds weight to the diver, it also adds a lot of volume, mostly as air spaces. This makes the divers less dense (or more buoyant) than the surrounding water. To help counteract this floating tendency, members of the Dry Valleys' dive team wore a 40 pound weighted vest. Also, increasing water pressure pushing down on the divers as they descended reduced the volume of air in their suits nd helped them sink.

Next >>