Tarp Size Rules of Thumb?

John,

Can't comment on the 2 kids. But for me…

5' X 8' Poncho tarp requires a bivy for splash, etc.

8' 10' requires no bivy. Can sleep two people theoretically. But I almost never hike with company. I think this size would work for you.

I actually did take the bulls by the horn and developed a way to objectively choose my tarp size.

Assumptions: pouring rain, hunkered down for the day waiting for weather to pass, thus tarp needs to be staked to ground.

I measured myself sitting up to see how high the roof would need to be for my head to not rub. Measured width of my head at that height off the ground, then width of shoulders and height off the ground. Then I measured myself laying down and how much space had to be over my face so I was clausterphobic, and width and height off shoulders for comfort. Then I plotted models of myself sitting at the midline of the tarp, and two of me sleeping on backs with enough space for a child in between. I did this all in sketchup. Then I mapped an A-frame over these figures.

All that said, I came up with 10 feet wide (almost exactly), 8 feet long (a bit more arbitrary -but I am making separate beaks).

Once I had those dimensions, I then went on to sketchup multiple pitches to see if everything was still possible: lower wider pitches to get 4 people in and taller pitches when it is just myself and maybe a companion.

Overall, for purposes of multi-person utility without getting too large to make unweildy for a single individual, all all things in between, 8X10 seemed to be the ideal go-to size.

Cheers

John

I really like the tarp configuration depicted by Mike Clelland in the paperback "Lighten Up!" on the bottom of p. 13. That is one of the most stormproof setups I've ever used back in my tarping days.

But it requires what Mike labels as "quarter point" pullout loops sewn to the tarp at the proper locations. He has convienantly drawn a bird's eye view to show the pullout locations.

For a trial run I'm using an old urethane coated tarp to attatch tie-outs in the same pattern before getting a silnylon tarp with the same setup. As a dayhike leader I'll carry the silnylon tarp for emergencies. One pound is not too much to carry for a safety item for shade or rain protection for an injured hiker.

Oh, yeah, the size will be 10' X 10', as Mike describes.

Once you have a decent idea what size you'll need, I'd try a couple nights under a cheap blue tarp of those proportions. I'd hate to get $100 into a cuben tarp only to find I made it a foot too short.

John, I'm going through the same process as you with very similar parameters. Similarly, I have determined that an 8×10 is just about perfect: a palatial overnight retreat for the soloist and a reasonable emergency shelter for 2 or 3 dayhikers waiting for a storm to pass. In cuben it is still light enough. A larger size or a heavier fabric begins to get on the heavy side to me. I'm sticking with 0.74 oz/yard cuben for now, I'm not sure if I can keep the 0.51 oz/yard stuff from getting thrashed.

One thing you might try is to cut a 3 mil polyethylene drop cloth to your selected size and set it up for real. Cost would be just a few bucks.

I have a 8.5 x 10.5' silnylon tarp. I don't think I'd want to try to fit more than 2 people under it in a blowing rainstorm. I think I'd go with a 10'x10' tarp for three people.

See the flat tarps section of this site for ideas about how many will fit under what size:

http://www.owareusa.com/