This was cut and pasted on another forum I go to. I have no idea what the original source is.
Modern day adventurers have also been plagued by the problem of moisture accumulation in
sleeping bags. Twenty days out on the polar ice on his way to the North Pole in 1986, Will
Steger noted:
"I hefted my bag and found that it had gained about twenty pounds in
accumulated ice. The inner layers of insulation were still somewhat dry, but
the outer layers were frozen mats. We had been finding that a tremendous
amount of body heat was needed to bring the bags up to a temperature at
which we could sleep with minimal comfort. Some nights we shivered for
three or four hours before we dozed off. (Steger 1988) "
These sleeping bags had been specially made with 5.5 kg of polyester fibrefill and had a total
loft of 36 cm. They were designed with such a great thickness of insulation to compensate for
the expected accumulation of ice.
After 34 days, they tried to dry the bags with stoves in the tent. Steger reported:
"The effort proved futile. The volume of accumulated frost was now so great
-- some bags weighed nearly fifty pounds -- that the minimal heat from the
stoves merely redistributed the moisture rather than driving it from the bags
(Steger 1988)."
In 1986, another adventurer was attempting to reach the North Pole. Sir Ranulph Fiennes
made an attempt on foot, without support. Temperatures ranged from -47°C to -25°C.
During this man-hauling expedition he used an experimental polyester fibrefill sleeping bag
(DREO-X). He combined it with a separate waterproof breathable cover and an interior
vapour barrier. Despite these precautions, his 5.5 kg sleeping bag gained 2 kilograms in
sixteen nights. However, this amount of water did not make the bag uncomfortably cold or
noticeably wet (Osczevski 1986).
His companion used commercial down-filled sleeping bags, with a GoreTex outer shell and
was often cold. After two weeks, both of these bags appeared to be wet and the filling
material had become permanently compressed and was frozen into lumps.
Two years later, in the spring of 1988, a team of Canadian and Soviet skiers crossed the
Arctic Ocean from Siberia to Ellesmere Island. At first, all thirteen member of the Polar
Bridge Expedition slept and ate in a single tent. After a couple of nights, two of the
Canadians moved out to sleep in shelters made of snow. Richard Weber, who had served his
polar apprenticeship on the Steger expedition, was one of the "outside men". Weber’s
observations are particularly interesting. He noted on Day 5 that:
"All of the Soviets' sleeping bags, and indeed everyone's who sleeps in the
tent, are losing loft; the feathers are getting wet, and the bags are getting
thinner and thinner."(Weber 1990)
DRDC Toronto TR 2003-070 3
Laurie Dexter, an "inside" Canadian noted in his diary after three weeks that:
"The top of my bag is little more than a few layers of nylon fabric, with fistsized
or smaller lumps of frozen down scattered along the edges!"(Weber
1990)
The sleeping bags that were used in the tent were sodden with water. Weber was disgusted by
the conditions:
"It is so horrible in there. Every meal it is the same. We sit down and get
rained on. Chris [Holloway, the other 'outside man'] wears his GoreTex
pants to keep dry. This morning I brought my sleeping pad into the tent to sit
on. It slipped, and I ended up on Yuri's sleeping bag and completely soaked
my suit right through..." (Weber 1990)
Later, on Day 38:
"This evening I inspected Yuri's sleeping bag. It’s quite solid. It consists of
baffles separating icy lumps of down. There is really no insulation. He
would probably be better off with a few garbage bags, since they would be
lighter to carry, and just about as warm."(Weber 1990)
After a couple of weeks the effect of the different living accommodations on the sleeping bags
was striking. Those bags that had been used inside the communal tent were wet, thin and cold
to sleep in. The down had matted and balled, like the down filled sleeping bags used on the
1986 Fiennes expedition. The sleeping bags that had been used in unheated shelters still
retained much of their loft and insulation although some balling of the down occurred around
the head.
Richard Weber was back on the Arctic Ocean in 1992. The Weber-Malakhov expedition
reached the vicinity of the North Pole from Ward Hunt Island in Canada, skiing over the ice
without outside support. Each morning, before lighting the stoves and warming the tent, the
members of the expedition crawled out of their sleeping bags, dressed, brushed the frost off
the tent and sleeping bags and then placed the bags outside.
Weber's sleeping bag was filled with 1.1 kg of high loft down. It had an integral pad
consisting of a full-length layer of closed cell foam, 1-cm thick, with an additional 5-cm layer
of open-cell foam under the torso. Even though he used internal and external vapour barriers,
frost still collected in the outer regions of the sleeping bag. However, because it was never
allowed to warm up in a heated tent, the ice stayed as fluffy frost. Although the bag became
heavier, it stayed thick and warm. Weber suspected that the frost might even have made the
bag warmer, as during the coldest part of the expedition he was able sleep using only a single
sleeping bag although he carried a second one to fit inside the first (Weber 1992). Weber and
Malakhov have since made the round trip from Ellesmere Island to the Pole and back again,
using only those supplies that they had with them when they first left land.
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Originally Posted by Crawldaddy
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