Apr 5, 2010 at 12:06 pm #1257340
THE MYTHS OF TARP DURABILITY
It is a truism in the lightweight community that modern high-tech materials are less durable than more traditional tarp materials such as nylon or polypro. Challenged by a fellow forum poster I decided to test this out with a little survey of tarp users here on the site. This post is my report based on the findings of that survey, and, while this is not truly a scientific study, I think there are some gems in here, both in terms of relative durability of different tarp materials, and development of best practice in how to care for our modern lightweight tarps.
This survey dispels the myth that Cuben Fiber is less durable than other modern materials in tarp construction. In fact, Cuben Fiber performs comparably with more common SilNylon tarp materials, and is more durable than SpinnTex/Spinnaker materials in real world use.
Note: Comparison with traditional tarp materials such as nylon or poly was not possible in this survey, since the sample size for these materials was too small.
In my opinion, there are two other important findings in this research related to the behavioral drivers of durability in tarp use.
1. How To Pack Your Tarp
The survey asked two questions related to how users pack their tarps in their backpacks. First, we asked about stuffing, folding and rolling tarps prior to packing. Second we asked if the tarps was placed in the main backpack compartment, separate pack pocket or in a stuff sack or ziplock bag inside the backpack.
By combining the data on these two questions, it becomes clear that the best practice taught on the BPL Wilderness Skills courses (at least, on the one I attended) is absolutely correct – tarp users should stuff their tarps in the main pack area without using a stuff sack. This finding holds true for all tarp material types, and yields a damage rate of about half the average damage rate across all packing methods. Users who insist on using a stuff sack would be well-advised to carefully roll or fold their tarps before placing them in the sack, since stuffing a tarp into a stuff sack yields no benefit in terms of safety – in fact damage rates in the “stuff it in a stuff sack” group were slightly higher than the average across all packing methods. The “fold or roll it into a stuff sack” group yielded protection only slightly worse than the “stuff it loosely in my pack” group.
Which methods were most likely to lead to tarp damage? Surprisingly, the “stuff, fold or roll it into a separate pack pocket” groups were significantly worse than the other groups, implying that this method of packing tarps should be avoided.
2. Which Type of Pole To Use
The second significant finding of this survey was the relative safety provided by tarp poles versus trekking poles, and the relative lack of tarp protection provided by stick or tree hanging methods. Trekking pole use yielded about average damage rates. Users who use tarp poles to suspend their tarps showed an 11% damage rate, about half the damage rates for trekking pole users. Tree or stick hanging users had an increased damage rate (~30%). It is likely that this increase is due to the large proportion of hammock users, who show a higher likelihood of experiencing damage to their tarps than ground tarp users.
An Emerging Best Practice?
Best practice for tarp use, in terms of protecting your tarp from damage, would therefore be as follows:
1. Use the lightest material you can afford. Lightweight materials are comparable in terms of durability.
2. Carefully stuff your tarp into the main compartment of your pack versus rolling or folding it into your pack. If you must use a stuff sack, then you should roll or fold it into the stuff sack. Whenever possible, avoid using a separate pocket for your tarp.
3. Custom tarp poles for your tarp are a worthwhile investment in durability for your tarp. You should conduct a cost/weight/benefit assessment to determine if you would want to add tarp poles to you setup. If you choose not to add tarp poles, trekking poles are the next best thing. Sticks and tree hanging of tarps is are more damage-prone approaches.
Personally, I will be replacing my practice of rolling & rubber-banding my tarp in my pack to stuffing it in (just like Mike C! taught me). I already own a pair of carbon fiber tarp poles, but haven’t used them since I purchased my LT4 trekking poles last year. I think it is time for me to examine this practice and see if I can find a dual-use for these tarp poles to make it more desirable to bring them along.
I’ll let you know what I decide when the time comes. Cheers & happy trails!
Fully 25% of respondents have used their tarps for more than 30 days under the stars, about a half have used their tarps for between a week and a month under the stars. The remaining ¼ have used their tarps for less than 1 week. This reflects a pretty substantial body of knowledge on tarp usage, reflecting data from 1,000s of nights of usage by the BPL community.
Fig. 1: Tarp Use Experience
Fully 65% of tarp users use trekking poles to hold up their tarps. 22% report using no poles, about half of these respondents were hammock sleepers rather than ground sleepers. A small number of tarp users (7%) use custom or purchased tarp poles.
Fig. 2: Tarp Pole Choice
Tarp Types, Sizes & Weights
More than half of the tarps in use in our community are constructed of SilNylon, with Cuben Fiber being a close second with 29%, and SpinnTex or other Spinnaker materials in third place with 17%. The remaining 4% reflect all other tarp types (classified below as “Nylon/Poly”) reported in the survey. This makes comparison of modern to traditional materials impossible, since 96% of users in this survey used modern materials. However, comparison of the modern materials to one another is absolutely possible.
Fig. 3: Tarp Materials
On average, the weight of our tarps is in the 10-15 oz range, with fully 60% of the reported tarp weights being less than 15 oz. Roughly the same number (4%) of tarps were in each of the <5oz and >30oz categories.
Fig. 4: Tarp Weight
A little over half of the respondents reported using solo tarps, closely followed by 45% reporting on two person tarps, some used as solo since even these larger tarps are incredibly light. A small number (3%) of reported tarps were listed as “really large” or group tarps.
Fig. 5: Tarp Size
Combining these three data points, we can see that our average tarp weight by material and tarp size are as follows, we can see that Cuben Fiber is the lightest tarp material (averaging 7.1oz for solo), followed by Spinnaker/Spinntex materials (averaging 12.49oz for solo), silnylons (14.11oz for solo) and more traditional materials (28oz for solo) such as nylon or poly. Strangely, respondents using spinntex 2-person tarps reported a lighter weight than cuben 2-person tarps – this appears to be mostly driven by the high number of Gossamer Gear SpinnTwin tarps being used by respondents.
Fig. 6: Average Tarp Weights by Material and Size
A number of questions were asked on the topic of how users packed their tarps when backpacking. Almost half of users stuff their tarps in the packs in the morning, 30% fold, 13% roll, and 3% do some combination of folding & rolling.
Fig. 7: Tarp Packing Methods
But what do tarp users fold, stuff or roll their tarp into? Most users (58%) use some form of stuff sack for their tarp, with 34% placing their tarp loose in their pack (14%), either in the main compartment with their other gear, or in a separate pocket in the pack (20%). 3% use a ziplock to pack their tarp.
Fig. 8: Tarp Isolation Method
There is no discernable difference in the practice of rolling/folding/stuffing based on whether the user uses a stuff sack, separate pack pocket or carries their tarp loose in their pack. In other words, the decision to fold/roll or stuff is unrelated to the decision to use a stuff sack, pack pocket, or main pack space.
Frequency & Severity of Damage
Twenty-seven of the 121 tarps (22%) had experienced some kind of damage in the field, with only one tarp (<1%) having damage more than 1in in size.
Fig. 9: Frequency of Damage
Within those 27 damaged tarps, 25 users either opted not to repair their tarps, or were able to duct tape or sew their tarps in the field, with 2 tarps requiring repairs which could not be accomplished in the field.
Interestingly, the highest rates of damage were reported with Nylon/Poly tarps versus modern high tech materials, although the sample size was very small (n=5), so this should not be used as the basis for any significant conclusions. Within the modern high tech fabrics, Cuben Fiber and SilNylon performed similarly, with 20% or less damage rates, which SpinnTex/Spinnaker fabric performed worse with a 30% damage rate. The overall damage rate of 22% reflects the high percentage of SilNylon tarps included in the sample.
Fig. 10: Damage Rates by Tarp Material
Behavioral Drivers of Damage
In addition to the findings with respect to Spinntex/Spinnaker materials, it appears that two user choices are also drivers of damage to tarps by active tarp users.
Packing method is a driver of damage to tarps. The most damage-prone packing method is to stuff your tarp into a separate pack pocket, with a 55% damage rate amongst those users who pack their tarp in this way. Next worst is folding or rolling your tarp, either in your main pack or in a pack pocket (~30% damage rate in these circumstances). Stuffing your tarp into a stuff sack provides some protection for a tarp, but still has a 24% damage rate. The two methods providing the safest handling of tarps are stuffing your tarp loosely in your pack (11% damage rate) and folding/rolling it in a stuff sack (14% damage rate).
Choice of poles is also a driver of damage to tarps. Trekking poles are the method of choice for most users with a 23% damage rate amongst this population, tarp poles users are much less likely to experience damage to their tarps (11%) and hammock, tree or stick users are somewhat more likely to experience damage to their tarps (30%).
Fig. 11: Damage Rates by Pole Choice
The survey was posted on March 31, 2010 and data was collected from random posters until April 2, 2010. A total of 121 tarp users from the BPL community completed the survey, 46% of these respondents reported having over 10 years of backpacking experience, 20% having 5-10 years experience and 21% 1-5 years experience. Just one novice backpacker (with less than 1 year of experience) completed the survey. This is a pretty solid, experienced population and very likely reflects the average experience levels of BPL forum users.
Fig. 12: Backpacking Experience
Also note that over 80% of respondents classified themselves as either ultralight or lightweight backpackers, claiming (5 day) base weights between 5lbs and 20lbs.
Fig. 13: Approximate Base Weights for 5-day Backpacking TripApr 5, 2010 at 12:36 pm #1594483
Richard NisleyBPL Member
@richard295Locale: San Francisco Bay Area
Great work… thank you!Apr 5, 2010 at 12:48 pm #1594490
@davecLocale: The West Slope
Very nice write up.
Got an SPSS file to share? ;)Apr 5, 2010 at 12:56 pm #1594496
Jay WilkersonBPL Member
@creachenLocale: East Bay
Thanks James for all your hard work on collecting the data.. Very interesting–This should up your BPL ranking?!?!?!?
-JayApr 5, 2010 at 1:04 pm #1594501
@jay: LOL. There's another hypothesis to be tested, I guess. :-)Apr 5, 2010 at 1:04 pm #1594502
@retropumpLocale: The Antipodes of La Coruna
Although factors such as type/material/packing method/pole use etc may be important, IMHO the design and construction methods are far more important. Silnylon is very much more forgiving of poor stitching or poor design. Cuben is very unforgiving. Also missing is the climate or common weather patterns that the users of tarps are likely to encounter. If you encounter unseasonable conditions I suspect his also has a big impact on how your tarp will perform…Folks that choose a tarp are usually not expecting prolonged really foul weather in my experience. YMMV.Apr 5, 2010 at 1:05 pm #1594504
. .BPL Member
@biointegraLocale: Puget Sound
Thanks for sharing this James!
I especially find the correlation between packing methods and damage useful and interesting.Apr 5, 2010 at 1:09 pm #1594506
Hi! All valid comments, and if we were doing this as a scientific study, all things to control for. I did do a quick review of the damage types – including questions on whether seams were stitched, glued or taped, whether lateral tears, punctures etc. Almost all the damage reported was at seams, and all but one was less than 1 inch in length.
To really understand breaking dynamics you'd need to get hold of each tarp and test them until they were destroyed. This survey was simply to put a user perspective on the question, which is why I concluded more about best practice in terms of behavior with your tarp, that drawing conclusions about tarp construction. Hopefully, the best practice would hold true in most conditions!
Anyway, thanks a bunch for your comments…
Peace, James.Apr 5, 2010 at 1:14 pm #1594508
Stephen BarberBPL Member
Does your data distinguish between using the handle end of a trekking pole vs. the ground end?
I'm guessing that the sharp tip would be much more likely to cause damage than the foam rubber handle.
Secondly, in your estimation, what about folding/rolling damages the tarp? The creation of weak points where folded?Apr 5, 2010 at 1:15 pm #1594509
This reminds me of an old Styx song. Guess which one?Apr 5, 2010 at 1:23 pm #1594512
Sam HaraldsonBPL Member
@sharaldsLocale: Gallatin Range
Well done, James.Apr 5, 2010 at 2:00 pm #1594523
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
A most excellent bit of work! My compliments.
However, I do have one doubt:
> Packing method is a driver of damage to tarps. The most damage-prone packing
> method is to stuff your tarp into a separate pack pocket,
I am not convinced by this correlation. There may be a statistical link, but that does not prove causation. It is equally possible that other user factors provide the causation, like (for instance) experience.
Let me put that a different way. What sort of damage are we talking about? If it is small rips or punctures which happen while the tarp is pitched, then how it is packed is not going to be causative, not matter what the correlation.
For instance, I stuff my tents into a stuff sack. But the only damage that has happened to them has been caused by other factors: small sticks poking holes in the groundsheet, damage to the pole tube when a pole snapped, and snags in the UL netting due to catching on vegetation.
So, we need to look into the data a little more deeply. Hum?
CheersApr 5, 2010 at 3:33 pm #1594550
@bderwLocale: Northeast Pennsylvania
To those who stuff their tarps into their bags, where do you store the stakes? I don't normally carry any ditty bags, just an Aloksak that holds my toiletries and ID.Apr 5, 2010 at 5:41 pm #1594596
Gerry B.BPL Member
@taedawoodLocale: Louisiana, USA
From my reasoning, the last place I would want to put my loose tarp would be in the main compartment of my pack, especially when it is wet and/or dirty. Isn't that why so many pack designers are putting outside pockets on their packs so that wet and/or dirty gear does not mess up the gear in your pack?
I would be interested to hear a response from those leading the BPL outdoor courses.Apr 5, 2010 at 5:47 pm #1594598
Jamie ShorttBPL Member
@jshorttLocale: North Carolina
James, That was a great piece of work. It is a BPL article quality write-up. Thank you for the insightfull write up.
JamieApr 5, 2010 at 6:28 pm #1594610
@cbertLocale: N. California
just speaking for my tarps, the only damage they seem to suffer is emotional. When I don't use a stuff bag, they feel left out, and when I do use one, they feel like I'm embarrassed by them and just want to hide them from the world.Apr 5, 2010 at 7:42 pm #1594634
Tom KirchnerBPL Member
@ouzelLocale: Pacific Northwest/Sierra
"From my reasoning, the last place I would want to put my loose tarp would be in the main compartment of my pack, especially when it is wet and/or dirty"
+1Apr 5, 2010 at 8:01 pm #1594639
@bderwLocale: Northeast Pennsylvania
Nah, you just stuff it in the bottom, then in goes the pack liner, then in goes your stuff.
Alternatively, you could seal the pack liner and stuff the tarp on top of everything.Apr 5, 2010 at 8:04 pm #1594641
@rosierabbitLocale: Pacific Northwest
James – thanks for the great work you did creating this survey and the summary charts.
As you say, "This survey was simply to put a user perspective on the question, which is why I concluded more about best practice in terms of behavior with your tarp, that drawing conclusions about tarp construction."
It would be interesting to find out if other variables might cause some of the tarp damage and whether the survey results would be the same for stuffing other silnylon shelters, such as tarptents, into a pack.
Did the instructors in the wilderness course describe any "whys" when they recommended stuffing a tarp into the pack? It really does seem counterintuitive.Apr 5, 2010 at 8:13 pm #1594643
Greg MihalikBPL Member
nmApr 5, 2010 at 8:24 pm #1594646
John DonewarBPL Member
@newtonLocale: Southeastern Texas
+1 to your take on the survey.
+1 & Insightful as always.
>>Packing method is a driver of damage to tarps. The most damage-prone packing method is to stuff your tarp into a separate pack pocket, with a 55% damage rate amongst those users who pack their tarp in this way. Next worst is folding or rolling your tarp, either in your main pack or in a pack pocket (~30% damage rate in these circumstances). Stuffing your tarp into a stuff sack provides some protection for a tarp, but still has a 24% damage rate. The two methods providing the safest handling of tarps are stuffing your tarp loosely in your pack (11% damage rate) and folding/rolling it in a stuff sack (14% damage rate).<<
Numbers and statistics can be misleading. I don't believe a tarp stored in a stuff sack is more prone to damage than one loosely "stuffed" into a pack. It is more likely that whatever damaged the tarp in the first place might be worsened by the physical act of stuffing an already damaged piece of gear into its stuff sack.
Is a racing driver who is tightly strapped into his car more prone to injury than one who simply climbs in a drives off without buckling up?
Party On ! 2010
NewtonApr 5, 2010 at 9:05 pm #1594659
Cayenne RedmonkBPL Member
@redmonkLocale: Greater California Ecosystem
Any link between nights under a tarp and experiencing tarp damage ?
Seems like the more use gear gets, the better the odds of experiencing damage.
Adding a question on *how* the damage occurred would be valuable.
(flying debris, high wind, tent stake, while packing, from trekking pole, etc)Apr 6, 2010 at 5:43 am #1594722
Thanks for all the excellent feedback… I'll try to answer as best I can, forgive me if I miss something, I'm running between work, teaching and taking classes this week!
1. Causality – this survey cannot establish causality for anything, since it is a point in time study. In order to establish the causes of correlation we would need to execute longitudinal studies using very tightly controlled / prescribed methods of (say) packing, erecting tarps under monitored (and therefore comparable) weather conditions. This is way beyond what I can handle off the side of my desk, but would definitely be worth while to establish the REASONS for these correlations, and even to confirm that these correlations exist!
2. Sample sizes – the total respondent base for this survey was 121 tarp users. Only one person put in more than one tarp, so this is 120 different people. While this is a decent (if not extensive) sample size at the 90% confidence level, individual cells within the study are far below statistical confidence level. This is why I called this a non-scientific study. What this DOES do is establish a basis to create a series of hypotheses which could be tested by other, deeper studies over time.
3. Stuffing vs rolling/folding – I too was surprised at the advice given on the BPL course re stuffing the tarp in the bottom of the pack, underneath the pack liner, but it actually is a good way to pack, allows you to shape your pack and prevents excessive folding or creasing of the tarp. If there was a deeper rationale than that, I don't know what it was (perhaps Mike C! could jump in on this!?). My observation / guess on the risk of rolling/folding is that this then creates a "solid" inside your pack, which is more prone to puncture from tent stakes, spork, etc, whereas a loosely stuffed (not stuff sacked) tarp might flex more and not puncture so easily. Since Mike C!'s advice is that your pack should be completely empty each night (and usable as part of your sleep system), and completely repacked each morning, you have the ability to carefully repack vs stuff the tarp in AROUND other things in your pack. Perhaps when you take a systems view, it makes more sense.
4. Tent stakes – I use a small MYOG nylon bag (made specifically for my stakes) to protect my fragile things from my stakes, and I slide it into what's left of the back pad space in my Jam 2 (along with my folded z-lite). This protect other things from my stakes, and means I can easily find them when I need them.
5. Next Steps – I plan to take this study, plus the feedback I have received and put together a set of hypotheses and a test plan for each hypothesis. I'd like to publish the study here and see if folks are up for turning it into a longitudinal study, with all that would entail (specific tests and documentation collected on trail while volunteers are outdoors with their tarps). In addition, perhaps BPL would be willing to sponsor a process for all of us to LOG tarp, hammock AND tent damage AS IT OCCURS, so that we can build a long term database of durability of our shelter systems. I think this is the only way to really establish best practice around these things.
Post if you are in support of this / willing to volunteer some time to complete documentation following a few backpacking trips over the next year or so, and I'll directly approach Ryan in a few weeks once I have the hypotheses established. It would also be great if one of the scientists on the form (Rog C????) would be willing to act as peer reviewer / advisor over time. Would love our comments on this?
6 – Perhaps in parallel with the data analysis which I am willing to pull together over time, there needs to be a gear destruction test or something like that, to test the resilience of construction methods/materials IN THE LAB. I cannot do that type of testing, but would LOVE to collaborate with someone who can. Please, if you are interested in collaborating on that – PM me!
7 – You will note that I did not publish any of the information about the different manufacturers, couple of reasons for that – primarily, this was not a supportable scientific study, so didn't want to bad mouth anyone, and secondarily, it wasn't an apples to oranges comparison. I think it would be great to do comparative studies on this, but that would need much deeper and more controlled samples.
Anyway, gotta head out now… but, once again, thanks for your feedback on this… keep it coming, as it will form a strong basis for the hypotheses needed for the next phase of this work.
Cheers and happy trails!
Peace, James.Apr 6, 2010 at 6:46 am #1594737
Even if stuffing the tarp at the bottom of the pack results in less damage statistically, it would never work for me. I always keep my tarp easily accessible so that it can be put up quickly in the rain and keep the rest of my gear dry. Having to pull everything out first and risk getting all my gear wet makes no sense. I guess people rely on their pack liners to keep things dry outside of the the pack too?Apr 6, 2010 at 6:55 am #1594740
Hi! Not trying to tell you how to do it for yourself… in every case, the macro analysis from a survey is a roll UP of the individual experience of the respondents, nothing more. In no way does this imply that you are being told to do something different. My editorial (and it is just that, so don't take it the wrong way) – you could just put your tarp in the top of your pack, on top of your pack liner, seems to me that would be a simple solution to the challenge, for the way you like to use your tarp.
Anyway, happy trails mate!
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