Ractents

John Herber Ltd / TA The Canvas Technology Centre, Christchurch, Kaiapoi, New Zealand

The Rac-Tent is a custom-built modular shelter system designed specifically for the support of scientific research in remote polar regions. Its award-winning design is based on a unique web-beam framing system that allows for an exceptionally fast assembly, rock solid security and a more effective interior work environment than possible with traditional tube-framed, dome or Quonset®-shaped shelters.

The client requested insulated modular blankets to cover the client’s award-winning modular framing system, for the use on accommodation shelters, mess hall shelters and scientific and workspace shelters in polar regions. Each blanket had to be UV stable on the outside, flame retardant on the inside and insulated to keep heat in and the cold out.

Rac-Tent shelters are used mainly in Antarctica by the U.S. Antarctic Program, Australian Antarctic Program and Antartica New Zealand, but are suitable for any cold climate or polar region.

Each blanket had to be modular to allow the shelters to be erected to any size in 4' increments, UV stable, flame resistant, insulated and a low total weight. Each blanket was manufactured in three layers. The outer canvas was an 8 oz poly/cotton that provided strength and UV stability. The inner canvas was a 12 oz poly/cotton to cope with the constant rubbing and flapping against the framework. The complication was that it had to be a certain color and flame retardant to US Building Code Standard to provide protection against the high risk of fire. There was no 12 oz flame resistant canvas available in New Zealand, so the supplier dyed the 8 oz and 12 oz poly/cotton to the color specs and the 12 oz was flame-resistant-treated during the manufacturing process. The insulation factor came from the layer of 500 gsm wool horse cover lining between the two layers of canvas. At each end of the blankets, a reinforcing flap enabled snow to be piled up on to give the shelter a complete draft seal. For this we used a strong vinylon sourced from Japan, specially designed to withstand extremely cold temperatures.

The overlapping joints on each modular blanket had to be weatherproof, so a covering band tensions down tight over each joint. These had to be extra strong because the client decided to add guy ropes to give the shelter even more stability in the harshest Antarctic storms. Other additions were to to enable some way of letting natural light in, so in some of the blankets had “sky light” panels using heavy duty sail cloth, which worked really well. In some blankets, heat-proof stove jack holes allow flue pipes of diesel heaters and stoves to pass through.

The client is satisfied both in the product and the workmanship, as well as in the knowledge that if the blankets need to be modified or customized, it can be done.