Inexpensive alternative to Ursack?
Jan 21, 2023 at 10:21 am #3771001
I recently bought and received this item:https://www.aliexpress.us/item/2251832858467638.html?spm=a2g0o.order_list.order_list_main.5.715b1802mAxpWW&gatewayAdapt=glo2usa&_randl_shipto=US
It looks to be made out of the same material as the pants I had earlier bought/received from this thread:
The material has a high content of UHMWPE fibers/yarns (the bag is knitted btw). This is obvious because of the high thermal conductivity and high cut resistance of the fabric.
I know what many of you are thinking, and would probably say if I don’t address it first. Yes, I know that Ursack is a legally accredited and tested product that is required in certain areas (along with bear canisters). This wouldn’t be for those areas. If you are concerned with legality, fines, etc, then stick to the law. I’m not advocating that anyone break the law.
For other areas: If modified, it possibly could be used as a bear barrier? First modification would have to be to have the nylon cord taken out and replaced with UHMWPE cord (easy enough to do). I would also reinforce the seams with stronger thread (probably black kelvar/aramid thread) just to be on the safe side. I would personally line it with/put a sleeve in there with either the heavier Mountain silnylon for slobber protection, or a mylar-aluminum foil lined bag for both slobber and smell protection.
I also thought of a lightweight way to decrease crushing if a bear does try to get into it. Take some bamboo and reinforce it with S grade fiberglass cloth and/or kevlar tow or the like + epoxy + spray or poured CCF (in the core of the bamboo. The combo of all of the above, makes for a very strong and durable for the weight material). Line the bag towards the bottom with one or two reinforced bamboo poles cut to size (note, the ends would probably need to have a soft, non abrasion material put on them, such as silicone, vinyl, rubber, etc). Then, going the opposite way, put another reinforced pole towards the center. These poles fitted to the fabric stretched out should tend to keep a strong and stiff structure to it, decreasing crushing/pulverizing of food within same.
The biggest/most common complaints of Ursacks is one or more of the following: slobber and crushing/pulverizing of food.
Note, if I was using the pole/structure adding method, I wouldn’t put it directly inside a mylar bag with aluminum foil liner–that would too easily rip and/or abrade that material. I would probably first line it with the Mountain silnylon and then put a mylar bag over that. With that said, from my research into vacuum systems and materials, a properly sealed mylar bag with aluminum foil liner inside, would limit odor diffusion enough that the food contents within same would become invisible to the bear’s sense of smell. Aluminum is a very good gaseous barrier; far, far better than most plastics. So hopefully one wouldn’t need the poles to begin with.
Should also note that the bag is smaller in person than it looks in the pic with the model wearing it. That model must be a very short and slim person. If anyone is interested in the exact, at least flat dimensions, let me know and I will get back to you with those. It does have a slight box cut/structure to the bottom, so it is slightly dimensional in shape/structure (i.e. they didn’t just sew two fabric pieces completely flat to each other to make a simple sleeve, like a pillow case/sleeve).
So much stuff costs so much. I like to try to provide alternatives to people who, like myself, don’t have a lot of disposable income.Jan 21, 2023 at 10:35 am #3771002
I was in Trinity Alps
Someone had hung ursack from tree, I don’t know how well they did this
A bear got into it and ate the contents
I question whether a bag like this is bear proof
This is just one data point, doesn’t mean that ursacks are useless. Maybe hang it from tree 10 feet above ground, 10 feet away from tree, like a regular bear hang. The ursack would give one more layer of security. It would at least keep out rodents or birds climbing on tree.Jan 21, 2023 at 10:56 am #3771003
Yeah, if you read the reviews of Ursack, sometimes bears do get into them. Sometimes it is user error and sometimes it is design fails.
The regular ones are apparently more prone to small rodents getting in.
The bear hang is a good idea and makes sense, but yet takes away from what is supposed to be the convenience factor of these not having to do that.
I’ve not seen an Ursack up close in person, but I can tell from the pics that it’s a tighter weave than the bag that I linked and have. The latter would probably need to be lined with an even stronger material than I earlier suggested (Mountain silnylon) because of that. This might tip the strength to weight ratio too low to where a bear canister becomes more practical than a bag design.
There is a reason why I put a question mark in my subject title, because I’m not certain.Jan 21, 2023 at 2:14 pm #3771027
Yeah, ursacks are a great idea. Probably work most of the time. It’s not always possible to find a proper tree to hang a bag from. On that same trip to Trinity Alps, someone else used ursack successfully.Jan 21, 2023 at 2:42 pm #3771032jscottBPL Member
@bookLocale: Northern California
If one is relying on a hang for the Ursak…what good is it really? If the bear gets the hang, it will carry the sack off into the woods to chew on it, or will if you get up and try to retrieve it from her. what are the chances of finding it again, all slobbered on and chewed to mush? I’m not sure.
A Bearikade scout is perfect for thee or four day trips. Pricy, however. Lasts a life time tho. Very light. Doesn’t take up much space in the pack.Jan 21, 2023 at 6:58 pm #3771042Todd TBPL Member
@texasbbLocale: Pacific Northwest
If one is relying on a hang for the Ursak…what good is it really?
The Ursack shines in the scrubby zone near treeline. With real trees I always prefer a good PCT hang, even if my food’s in an Ursack, but with nothing but short stocky subalpine firs (or whatever), the only other option is a can that weighs 2 lb more and is awkward to pack/carry.
If the bear gets the hang, it will carry the sack off into the woods to chew on it…slobbered…mush
There’s little question that bear cans are superior protection. But they weigh 2 lb more and are awkward to pack/carry. I love my Ursack in the right conditions.Jan 21, 2023 at 8:42 pm #3771044Bill in RoswellBPL Member
@roadscrape88-2Locale: Roswell, GA, USA
I use an Ursak in bear heavy areas along the AT in GA and NC. Bears regularly defeat hangs, crawling out a limb and dive bombing the bag. An Ursak properly tied to a stout trunk or limb will be mastecated, but not taken away. Old sun damaged Ursaks will soon shred. Newer versions are more sun damage resistent. BTW, the AT from Carter Gap NC to Silers Bald NC is notorious for smart black bears. They do kick bear cans downhill into laurel thickets whether they meant to or not.Jan 22, 2023 at 6:01 am #3771054David HartleyBPL Member
@dhartleyLocale: Western NY
WRT the original subject of the thread – not sure how you would go about testing a homemade Ursack with any degree of confidence. And I am not sure the cost of purchasing one is more onerous than the hassle of trying to make your own – unless of course you have been bitten by the MYOG bug.
On the subject of Ursacks. I use bear cans when required, I use bear bag hanging when hiking with a partner, and I use an Ursack when solo for less overall hassle.
When solo I find the convenience of the quick tie off to a tree very compelling. Campsites are often convenient to water, but for LNT reasons not close to water (in the ADKs 150 feet or more away is required, although some older lean-tos and designated campsites are closer). I often set up my camp and relax for a few minutes before getting water. It is nice to not have to find a bear hang and instead quickly secure the Ursack to a tree, grab my water stuff, and head to the water source knowing my food is reasonably secure. Same thing in the morning after coffee and breakfast – I can quickly secure my Ursack to a tree and find a suitable spot for my morning constitutional (or head to the privy if there is one) without having to go rehang my food bag. Sure – I could modify my behavior in camp – getting water before setting up camp, packing and bringing my entire kit along for the morning poop run, etc., but I find an Ursack on solo trips makes camping a much more relaxed experience.
Of course – this assumes camping in areas where bears are not showing up nightly looking for campers food. In that case I would use a bear can.Jan 22, 2023 at 7:58 am #3771064
The Bearikade Scout is a fine piece of equipment, but yes, sure is pricey at 326 dollars. And the Expedition at 424. Not everyone can afford this kind of equipment.
As far as testing the bag linked–I suppose one would have to test it the way that the company did–have some bears try to get into it. I could only test against black bears since I’m nowhere near any brown. I imagine a cheap trail camera would come in handy for such a purpose. Thankfully the bag is only like 27 dollar shipped. (The mods would add a little extra cost, but not much). If I’m going to do something like this, then I may as well throw in a homemade bear canister too.
You can buy 6″ diameter bamboo for quite reasonable. You can get a 2′ long x 6″ diameter bamboo pole for 12 dollars and some change. A lot of people don’t know this, but S grade fiberglass actually has higher tensile strength than commercial, common grade carbon fiber. It is also a generally tougher and more durable material than carbon fiber (this is because it will stretch some before breaking–it is very similar to nylon vs polyester in some ways). The only thing that carbon fiber has on it is a higher stiffness (Young’s Modulus) strength. But this is less important for this application, because a bamboo column is already going to have a lot of stiffness strength to it.
Point being, if you reinforce the bamboo pole with S grade fiberglass and a high quality/strength epoxy (both of which I have some left), you could get a very strong structure. I can also throw in some carbonized cellulose nanocrystals (which I can make cheaply and which are like a nature closer version of carbon nanorods) into the epoxy to increase various strengths at low weight.
* The trick to making high quality cellulose nanocrystals is unlike industry which typically uses waste wood cellulose sources (saw dust etc which is low in crystalline cellulose), if you start off with a cellulose source that is already high in crystalline cellulose (some are from around 60 to 70% or so), you can get a very high content of CNC right off the bat. Then carbonizing it is easy.Jan 22, 2023 at 5:07 pm #3771096Nick GatelBPL Member
@ngatelLocale: Southern California
I have used a Ursack since around 2008 — it is no longer approved in the areas that still accept the newer versions. I double bag my food with Nyoflume bags, am careful to secure it to a large branch or smaller tree trunk using the knots recommended by Ursack. Probably more important, I only use it in areas where few people frequent, diminishing the chance of a bear encounter.
Nowadays, I mostly use a BV450 or BV500 because it is just so much more convenient. At my age I am very weight conscious and take little in the way of “luxuries” but keeping food safe isn’t a luxury. Again, even with the Bear Vaults, I am unlikely to sleep where people or bears are numerous — this is, IMO, the most important factor.
The BV500 and BV450 can be purchased for under $100. The cheapest Ursack is over $100 and I don’t think this includes the aluminum liner, which is an additional $25. I wouldn’t want to experiment with a less expensive alternative (meaning a bear would attack it), since testing it might result in losing my food.Jan 23, 2023 at 7:05 am #3771125
“Probably more important, I only use it in areas where few people frequent, diminishing the chance of a bear encounter.”
on that Trinity Alps trip, the person that camped next to the trail had their ursack broken into
we were maybe 0.1 mile away from trail and didn’t have a problem.Jan 23, 2023 at 5:06 pm #3771211Sam FarringtonBPL Member
@scfhomeLocale: Chocorua NH, USA
Disclosure: Although I’ve not backpacked in northern Montana in areas where grizzlies are prevalent, I did take one trip northward from Banff in the Canadian Rockies, and was confronted by two grizzlies. Scat left at many places on the trails suggested they were very prevalent. Fortunately the two I met were not interested in me, just the pack, and my food had been stashed in a nearby cabin. That was enough to give up on trekking grizzly haunts, however. And I turned to Wyoming and Colorado for backpacking, not that those states don’t have black and even blond bears.
The most concern involved treks in Colorado where I had to to hang 7 day food caches at some points because there were no cabins, lodges or bear boxes in some places on the routes. This exposure meant that bears could have uninterrupted week long opportunities to get into the caches.
For those caches, Spectra/kevlar woven Ursacks were hung bearing doubled inner Opsac odor proof food bags rolled at the openings and sealed with small clamps that were posted about on BPL. The outer bag was then hung from a limb at least 15 feet high, using the cord-tied-around-a-thrown-rock method. The cord was strong and tear resistant, and it was wrapped several times around the tree trunk to avoid tempting bears to sever it and allow the Ursack to fall to the ground. The trees were always located well into the forest and away from game trails.
There were 4-5 times when the Ursacks were hung in the above manner, and when I reached the caches, they were unmolested. I did affix a small sign asking humans who ran across the hung caches to leave them be, and rehang them in place if cut down. And offering $50 with my name and mailing address to anyone who did so.
The caches never showed any signs of molestation, and the signs appeared untouched. While all this may sound over-redundant, the alternative of having to bag a trek would have been worse, as was noted when health issues interrupted a couple treks because the human proved to be the weakest link.Jan 23, 2023 at 7:09 pm #3771225baja bobBPL Member
I doubt S-glass and bamboo is going to put up much of a fight for a bear. A few bites into the fiberglass and it can be ripped right off the bamboo. The bond between bamboo and S-glass is not going to be very strong.Jan 23, 2023 at 9:40 pm #3771241
Thank you to Nick, Jerry, Sam, and others for sharing their experiences with different systems.Jan 23, 2023 at 10:09 pm #3771242
“I doubt S-glass and bamboo is going to put up much of a fight for a bear. A few bites into the fiberglass and it can be ripped right off the bamboo. The bond between bamboo and S-glass is not going to be very strong.”
S-glass fiberglass is ridiculously strong and tough stuff. The only thing that regular/common grade carbon fiber has on it is stiffness strength. Meanwhile, S glass handles impacts and sharp, pointy stuff… way better than carbon fiber. (And yet, what are the Bearikades made with?)
When you sand the first layer off of bamboo, which is very silica rich (the silica can make problems for very good bonding), it then becomes like bonding epoxy to most non oily woods i.e. the epoxy bonds to it and the S-glass extremely well. (And like anything you plan to put epoxy on, you want to rough up the surface first anyways–somewhere between 80 to 120 grit is a good range). As I have mentioned, I have made composites with bamboo and various reinforcements. My journey started with this in relation to bikes, and figuring out what would make a good reinforcement for bamboo on a bike. Carbon fiber was a no go because when carbon fiber gets warmer, it very slightly contracts, while bamboo expands with heat and/or moisture (hence if carbon is tightly wrapped around and bonded to bamboo, it can crack it due to the difference in expansion/contraction properties). Thankfully, I didn’t find this out the hard way, because a bike making company did that for me–Calfee (I still made a composite pole out of curiosity though). After Calfee realized (via the hard way of experience) that carbon fiber wasn’t a good reinforcement to bamboo, they switched to E grade fiberglass. It should be noted though that there are significant strength differences between E and S grade fiberglass both in tensile and Young’s modulus strengths. S glass is very slightly less dense than E glass, but with about 25% higher strength in the former two mentioned areas.
Then consider that bamboo is already like natures fiberglass, then chances are, a bamboo column reinforced with high quality, high strength epoxy and S-glass, will stand up well to bears. Rarely in composites and composite use/structures, is a core material so strong as bamboo used–and that is just the core.
I guess fiberglass sounds less sexy than carbon fiber, but in anything that doesn’t need a very high stiffness above and beyond anything else, I would choose S-glass time and time again over carbon fiber, both for material properties and for expense.
Kevlar is the one that is a bit harder to bond well with epoxy. And forget bonding epoxy to UHMWPE. Unless the surface is specially modified and/or its blended with a lot of carbon fiber or fiberglass, it’s a complete no go.
The following is a very good primer on reinforcements for composites in relation to epoxy btw:
p.s. and I have access to a “secret sauce” that few so far use, carbonized cellulose nanocrystals. Carbonized cellulose nanocrystals are like a more nature made version of carbon nanorods (first you have to isolate/concentrate the crystalline cellulose and then carbonize it–neither of which are particularly hard to do once you read through the research literature and give it a go a couple of times. And sulfuric acid is not nearly as scary as many make it out to be). 2% of this powder by weight, added to the epoxy will up all the various strengths of the composite.Jan 24, 2023 at 2:27 am #3771244John S.BPL Member
The ursack needs competition. I would like to see another fabric bag undercut their prices.Jan 24, 2023 at 7:50 am #3771252Ben H.BPL Member
@bzhayesLocale: No. Alabama
…S glass handles impacts and sharp, pointy stuff… way better than carbon fiber. (And yet, what are the Bearikades made with?)….
Yeah, but Bearikades don’t hold up too well against Grizzlies, who are the only remaining testers of food storage devices. Bearikade still exists because they were able to get certified with black bears. New devices don’t have that opportunity.Jan 24, 2023 at 4:26 pm #3771338
“The ursack needs competition. I would like to see another fabric bag undercut their prices.”
Don’t know if this is the material to do it or not, but +1 to the above. I’m going to be experimenting with some double TPU bonding with UHMWPE fabric in between and see how that goes, as well.Jan 24, 2023 at 4:40 pm #3771343
“Yeah, but Bearikades don’t hold up too well against Grizzlies, who are the only remaining testers of food storage devices. Bearikade still exists because they were able to get certified with black bears. New devices don’t have that opportunity.”
To the latter, interesting, wasn’t aware of that. To the former, I’m out of the loop–so these are becoming known to fail in relation to Grizzlies? Imo, all the more reason to switch to S glass. Not only does it have higher tensile strength to weight ratio than common carbon fiber, but it is far more tough and durable of a material.
The only issue I can see with the bamboo core is that as far as I know, you can only get bamboo (online, in non bulk quantities) up to 6″ in diameter. Ideally you want the structure to be wider than that to make it harder to bite, grip well, etc. I wonder about the idea of putting a non food based wax coating (like paraffin) on the outside to make it more slippery though. Perhaps even put some ground up copper particles into it as well. From what I’ve read, a number of animals really, really dislike the feel/sensation of copper in their mouth, which is why copper mesh is used to line problem holes etc in buildings to keep out rats, mice, etc.Jan 24, 2023 at 4:48 pm #3771345Nick GatelBPL Member
@ngatelLocale: Southern California
The ursack needs competition. I would like to see another fabric bag undercut their prices.
Sure, but good luck getting certification in an area that requires bear canisters.
I like the avoidance strategy best, and as I mentioned earlier, I am just bringing my canister more and more often.
When I started backpacking the population in California was around 18M and now it is almost 40M. Add in printed trail guide books, the Internet with trail guides, trip reports, GPS tracks, etc. and it should be obvious we don’t have a bear problem, but a people problem. Before 2010 less than 1,000 people attempted to thru-hiked the PCT each year. Now it is over 7,000. Many other trails have become just as popular. When I was young no permit was required anywhere — now a permit is required in so many places, often via a limited lottery.Jan 24, 2023 at 5:25 pm #3771351
To be honest, I am most interested in the food “ninja’ing” concept. If you properly seal up a mylar-aluminum layer bag, not even a bear will be able to smell the contents in same. Things like PET, PE, nylon/polyamide, etc plastics do not compare to the gaseous barrier properties of aluminum.
Aluminum is so good at this, that it is the fundamental and essential barrier material in vacuum insulated panels–some of which are rated up to 50 years to hold a high enough vacuum to provide very high insulation value. It has to be combined with good getters in this case, only because the plastic layers will off gas, the micro gaps between the plastic and Al layers do allow some gaseous permeation over time, and/or moisture vapor ingress also through those micro gaps. But the Al layer itself is doing most of the important work of being the gaseous barrier.
Bears have a very impressive sense of smell, but not even they can smell something that is not exchanging molecules with the ambient atmosphere. The only smells they will smell, will be faint residual type scents from handling the outside of the bag with hands etc. And for most bears, most of the time, that is not worth the risk to investigate, especially when the average hiker already has all kinds of interesting residual smells all over them and their equipment. They are usually looking for the direct, concentrated stuff i.e. enough food for a meal of some kind.
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