[pct-l] Bear Can Cost/Materials (was Bear Cans)

[stevesgt at effable.com (Steve Sergeant)]

dude typed:
> why can't they make a super-light Ursack-type product that can
> withstand attack from bears?

"They" have, it's called the (third-generation) Ursack TKO.

> If kevlar can stop a bullet, shouldn't it be able to stop a bear?

Different problem, different forces. A single bullet is a relatively blunt
impact compared to a bear's teeth, and considerably less persistent.

Any woven fabric is subject to some movement of the threads with respect
to each other, allowing small holes to be opened (otherwise, one couldn't
sew it).  SIBBG feels that if a bear can get the smallest amount of food
out through the weave separations, then the bear has not been discouraged.

However, at least in the Folsom Zoo tests, bears were not able to do this
to the Ursack TKOs.

>  Just make the whole damn pack out of it and
> now you don't even need a can.  I hear that spectra is even tougher and
> lighter than Kevlar.

The Ursack TKOs are made from Spectra, about 4X the tear resistance of
Kevlar.  The original models were made with Kevlar, and have long since
been discontinued.

> I don't know anything at all about these
> materials, but I guess its the seams that fail.

The last published Ursack failures were seam failures. A subsequent
redesign eliminated all exterior seams on the bottom of the bag.

> I guess the other problem would be that your food would be smashed up
> and/or carried off by the bear.

If you've tied it down according to instructions, they're not likely to
carry it off. However, as a Sierra National Forest ranger said to me,
"even if they don't get your food, after they've chewed on your sack,
you'll wish they had."

All of that said, I still find the Ursack, in conjunction with the
odor-proof liners, a completely reliable solution in areas where bears are
not "urbanized". In places where bears are no longer really wild, like the
heavily used areas in the Sierra, they appear to be inadequate. Even if
they don't smell food in the sack, they have a history of success getting
food from hanging bags near hikers, so they'll persistently work to breach
the sack, and SIBBG feels there is a chance they'll succeed. For now,
hard-sided canisters seem to be the most reliable deterrent.