.51 cuben and .74 cuben

I have a .51 CF tarp from Hammock Gear and would say it's pretty transparent. I don't think it would provide much shade from the sun. If I had the option I would choose the .74. The weight increase is pretty small for a more durable material.

Kind of what I was thinking. I do love my .74 cuben patrol shelter. IT's just perfect.

Zpacks uses the .51 cuben in their shelters and tarps. I have owned two of them. Never had any durability issues with the .51 cuben in a shelter. I think it comes down to a weight issue. If you are really counting ounces and grams, I think it matters. If you are cost sensitive, as in pricing the cost per ounce of your kit, which is something I look at when trying to lighten my kit, going with .51 cuben over .74 cuben can get you a few "free" ounces as well.

In this case, the weight difference between the Canopy 2 in .51 and .74 looks like 2.5oz per BPWD specs. The price looks the same, so the 2.5oz is "free" in my book, to either take off your total base weight or to "invest" in a heavier piece of gear. You can think of it as a cuben cap and trade. Save 2.5 ounces here lets you spend it somewhere else in your kit or save it. 2.5 extra ounces of scotch in my pack is worth it's weight in gold. If you care for your gear, I don't think the durability difference is that great, especially in a tarp.

"2.5 extra ounces of scotch in my pack is worth it's weight in gold." Cheers :-)

In a tarp or canopy the .51 weight cuben has been proven to be plenty durable. If you need shade or less transparency, the .74 is a darker olive color.

Christopher – Well, to be honest, I usually keep my hooch entirely off budget when calculating the weight of my food. Learned that trick from Congress. It's morale value is simply too great to cut ounces there.

Does anyone find that the .74 cuben provides significantly more sun shade then the .51? If it really does, that would be a valid consideration. I would love to see some wonky, way overly analytical test of the opacity of different weights of cuben!

Just to add something not already covered above, a BPL fellow member, Ryan Smith, had this to say over on a MYOG thread the other day:

.74 cuben has the same Mylar layer as .51. Think it's .08, while 1.0 cuben uses a .18 Mylar film. If memory serves, the 1.0 has the same spectra content as .74 only the film is different. I would have to dig out my spec sheet from CubicTech to verify."

If it's true, then it's certainly something to think about. I don't know how much the mylar thickness vs. the spectra content contribute to the abrasion resistance of the material, but I'd guess that the mylar thickness is very important. If this is the case, then maybe 0.51 cuben isn't all that much less abrasion resistant than 0.74 after all?

Anyone with personal experience doing an A vs. B comparison between the two can chime in.

IIRC, .34, .51 and .74 all have the same thickness of mylar, but the amount of dyneema increases wit each increase in material weight. So I would thnk they all have similar abrasion resistance but increase in tear stregth and, to some extent, puncture resistance.
I once made a stuff sack out of .34. In a moment of carelessness, I put my fingers through it while stuffing a sleeping bag into it. I don't think that would happen with .51. I suspect that resistance to puncture by something very sharp would be similar in the 3 grades, though.

The following is a list of the various weights and factory specs:

1.43 oz/yard—CT5K.18
1.0 oz/yard—-CT2K.18
.74 oz/yard—-CT2K.08
.51 oz/yard—-CT1K.08

The number before the K is the relative amount of dyneema, and the number after the decimal point/period is the relative thickness of the mylar layers.

I couldn't find the lighter version's (.34 oz/yard?) specs.

Edit–so that's how you spell dyneema…

.34 oz cuben is CT0.3K.08.

i have a zpacks shelter with .51 and an MLD duomid with the .74.

The .74 is more opaque and does give more privacy than the .51…but honestly, they are both serious hotboxes in the sun.