WTF is up with the new Sierra Designs tents?!

2:52 p.m. on July 17, 2015 (EDT)
chomper
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I've always been a big fan of SD. They always seemed to be designing good, innovative, and most importantly, sturdy tents while the competition were chasing lighter and less durable designs. I always felt bad for SD because all their tents were always just a tad on the heavy side, which must've cost them some clientel. But I loved the original Lightning (they have recycled that name now into a non-related tent...shame on you SD!).

But I just can't get over their new wacky tents. What were they thinking? In any kind of heavy rainy windy weather, I just can't see those open, hollow, square-ish desings being a very pleasant shelter. I watched their wind tunnel test video, and while those little things seem to have a survival limit of 30 miles/hr (which isn't that much...my Lightning use to do well in 45), you can plainly see that they act like parachutes. I don't think putting people inside would stop much of the shaking and flapping.

The reason it ticks me off so much, is because I always liked them for designing a tent that pitches fly-first in the early 2000's when no one else had the sense to do it. I just wish they could finally turn that design into a conventional, non-wacky, lightweight tent! Come on SD!!

Anyway, does anyone actually own one of those wacky things adn what's your experience?

8:47 p.m. on July 17, 2015 (EDT)
Franco
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"I always liked them for designing a tent that pitches fly-first in the early 2000's when no one else had the sense to do it"

In 1972 Early Winters were selling an integral pitch tent called the Omnipotent.

Jack Stephenson already had a similar product but (from memory) with a partial inner.

Mind you in 1948 a freestanding design was patented by Eureka and that I also think was a fly first (if not fly only...) design.

1:13 a.m. on July 18, 2015 (EDT)
Sean Van Cleve
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IMG_3467.jpg

This is something like a '13 SD Mojo 2 Hybrid, and I must say it is incredible. Unless you're talking about upside-down rain, this is a great sub-3lb. three season tent. 


2:32 a.m. on July 18, 2015 (EDT)
chomper
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@ Franco:

Interesting.

I know it's been a fairly standard feature on some British tents for a long time.

2:36 a.m. on July 18, 2015 (EDT)
chomper
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@ Sean:

Have you seen the new tents? They don't make the Mojo anymore. The new ones have no vestibules to shed wind.

6:07 a.m. on July 19, 2015 (EDT)
Franco
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Chomper

There are American manufacturers that do ,now, integral/fly first pitch.

Every Tarptent model is like that.

franco@tarptent

5:25 p.m. on August 2, 2015 (EDT)
Matthew Hadfield
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I also don't like the door.  It opens down.  So you are always getting over it.  I like I full fly as well.

10:56 a.m. on August 3, 2015 (EDT)
Tipi Walter
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Yes I see the problem with the open fly with no vestibule.  This will be a hassle in a blizzard or raging high wind rainstorm atop an open bald.

But what I find most perplexing is Sierra Designs use of low denier fabrics on their 4 season "moutaineering" tents.  Their light Flashlight 2 has a 75 denier fly and 70 denier floor, very important and adequate numbers when it comes to hydrostatic head and durability.

And yet their 4 season Convert 3 tent has a 20D fly and a 30D floor---tissue paper in my opinion. I have no use for a 30D floor in my tent---just put the tent up on a puddle of water and sit down for 5 minutes and see what comes thru the floor.

Another peeve of mine is the stink flame retardant tent fabrics produce and you're getting a dose as you sleep.  Not good. 

And BTW, I just got back from a July trip and got caught in a good deluge and was camping at a decent unused spot not in a mudpit etc.  Check out the video:

This is why floor denier is so important as are the coatings used to prevent seepage.

7:04 p.m. on August 3, 2015 (EDT)
Franco
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Different materials, so not comparing apples with apples.

I bet that the Convert fabric is stronger than the one used on the Flashlight :

Flashlight 2

Fly :75D Polyester Tafetta 190T, PU 1500 mm, WR, FR
Floor: 70D Nylon Tafetta 190T, NY T/F PU 3000 mm, FR


Convert

Fly Fabric:20D Polyester Ripstop, Silicone/1200mm PE, FR 

Floor Fabric: 30D Nylon Ripstop, WR/3000mm PE, FR

(Those specs are a copy and paste from the SD page.

The correct spelling is Taffeta)

11:22 a.m. on August 11, 2015 (EDT)
Family Guy
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Tipi Walter said:

Yes I see the problem with the open fly with no vestibule.  This will be a hassle in a blizzard or raging high wind rainstorm atop an open bald.

But what I find most perplexing is Sierra Designs use of low denier fabrics on their 4 season "moutaineering" tents.  Their light Flashlight 2 has a 75 denier fly and 70 denier floor, very important and adequate numbers when it comes to hydrostatic head and durability.

And yet their 4 season Convert 3 tent has a 20D fly and a 30D floor---tissue paper in my opinion. I have no use for a 30D floor in my tent---just put the tent up on a puddle of water and sit down for 5 minutes and see what comes thru the floor.

Another peeve of mine is the stink flame retardant tent fabrics produce and you're getting a dose as you sleep.  Not good. 

And BTW, I just got back from a July trip and got caught in a good deluge and was camping at a decent unused spot not in a mudpit etc.  Check out the video:

This is why floor denier is so important as are the coatings used to prevent seepage.

 Franco beat me to it, but in a nutshell denier does not determine hydrostatic head (waterproofness) nor does it determine tear strength.  Your commentary is factually incorrect as a generalization.

4:33 p.m. on August 11, 2015 (EDT)
Patman
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Franco and Family Guy (or of course anyone who wishes to opine),

I can understand how hydrostatic head may be more or less regardless of denier based on the applied coating (and perhaps tightness of weave?) but what is it that can make tear strength greater with a finer denier than a courser denier?

If denier is a unit of measurement representing linear mass density of a single strand or filament comprising a fabric, and density is the concentration of matter in an object, and the matter in both is nylon, how can a 70D fabric ever be weaker than a 30D fabric?  Does it not stand to reason that given the same nylon with the same properties and weave, the 70D example would be stronger fabric that the 30D example (simply having more matter)? Is the overall distinction the quality of the nylon itself? If so, how do you determine from examining a manufactures specification which nylon is better?

5:07 p.m. on August 11, 2015 (EDT)
Family Guy
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Patman, it will depend on the tightness of the weave and the coating applied to the fabric, not necessarily its thickness.  In addition, PU coating a fabric will actually weaken it over time (also providing less UV resistance).  

The point of the commentary was that there are many factors to consider and generalizing that a 70d fabric is stronger or more waterproof than a 30d fabric isn't necessarily true.  

Franco is sleeping.

6:47 p.m. on August 11, 2015 (EDT)
Franco
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Technically a denier is :

"a unit of weight by which the fineness of silk, rayon, or nylon yarn is measured, equal to the weight in grams of 9,000 metres of the yarn"

so if woven the same way a square yard of  70d fabric strand will be heavier than a 30d but not necessarily stronger .

If you take a piece of fabric (nylon/polyester)  and you coat it with PU (as a lot of tent fabrics are) you reduce the tear strength by at least 30% because the PU coating will concentrate the stress to a particular line .

If on the other hand you coat the same fabric with silicone , it increases the tear strength because the silicone is flexible and spreads the stress over a larger area.

Jack Stephenson and Bo Hilleberg discovered that a few decades ago.

(the Hilleberg "Kerlon" fabric is  siliconised nylon)

 

This is a comment from Outdoor Gear Labs on the matter :

Silicone elastomer coated nylons are used on all high quality backpacking and mountaineering tents. SilNylon is highly water repellant, elastic, and UV and temperature stable. SilNylon is considerably stronger, lighter, and more durable than PU coated fabrics. It's also much more slippery than PU, which makes it an ideal choice for winter applications because snow slides off easier. Silicone is widely regarded as the best coating for nylon fabrics used for pack tents.

Unfortunately, for the budget conscious consumer, silicone is more expensive than PU and coating a fabric with it takes longer than coating a fabric with PU; it's markedly more expensive. Furthermore, it's difficult to stick things to SilNylon, which means that the seams on silicone coated fabrics can't be factory taped. Thus, most "good quality" tents from major manufacturers use nylon that's coated with silicone on the outside and PU on the inside (the PU is then seam taped). Double-sided silicone coated fabrics are lighter, stronger, and more durable than PU/silicone combinations.

 

This is how Roger Caffin explains it :

Technically, the 'silnylon' fabric is 'double-coated'. That is, a coating of silicone polyer has been applied to both sides. Well, fair enough, but there is a huge difference in the result between PU and silicone coating. The PU coating sits on the surface of the fabric, but the silicone polymer goes right in. As far as I can see (with a microscope) the silicone polymer completely permeates the fabric fibers and forms a layer right through the fabric. As far as the final fabric properties are concerned, you should not think of 'silnylon' as a 'coated fabric', but rather as 'nylon-fabric-reinforced silicone polymer sheet'. This is a bit like fibreglass or glass-reinforced epoxy.

This difference translates into mechanical properties too. A key parameter is 'tear strength'. It is claimed that a PU coating focuses the stress in a tear right at the tip of the tear, and this actually makes a PU-coated fabric behave weaker than the base fabric. However, the elastic silicone polymer in silnylon fabric takes over and distributes the stress across a number of threads, and this makes the silnylon fabric significantly stronger in tear than the base fabric - reportedly up to 2.2 times stronger. Note this does not apply to EPIC fabrics.

 

Roger is a retired textile scientist working as a moderator for Backpackinglight.

 

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