Re: making 2 tarps
- For your purposes, the only use that a grossgrain perimeter would
serve is to make the tarps heavier. It has been suggested that an
edging like grossgrain may serve to stiffen a tarp's catenary edges,
but I have done no extensive testing on this hypothesis. If you feel
uncomfortable rolling the edges of silnylon, however, an edging may
allow you to "finish" the edges without having to extend beyond your
comfort level. Observing the pros, Integral Designs rolls the edge
twice (producing a fully-finished seam edge) and uses gross-grain on
the edge only for the tie-outs leaving three-inch tails to be sewn to
the edges to distribute the load. After using Integral Designs
products in varying climes for the past four years, I feel confident
that this is more than adequate re-inforcement.
More important than re-inforcements is the issue of the ridgeline.
Make sure that the ridgeline, or the primary direction of stress, is
parallel to the length of the fabric. Youngblood can explain this
more eloquently than I, but due to the nature of the fabric, silnylon
stretches the least along its length, and most along its diagonal.
To maintain a crisp ridgeline (and thus a more taut pitch), keep it
parallel to the length of the fabric.
-Jeremy Padgett (Hungry Howie & The New Sushi)
- Hey Wild Bill,
I have built a couple of flat tarps (8x10 and 10x10) as well as a
couple of tarps using catenary curves along the ridgeline and edges
(8x10 and 10x10). I have not used any edging material and would not
if I were to build one today. I would re-inforce the tie-out areas
with scrap nylon or silnylon material and seam seal all stitching. I
prefer a fairly diluted mix of clear 100% silicone adhesive and
mineral spirits, where I mix them in a small glass jar with a tight
fitting lid (by shaking) and use a 1" wide foam brush to apply.
David Oware has some diagrams that might be helpful at
http://www.owareusa.com/tarps.html that shows the tie-out arrangement
he prefers. A 10x10 tarp is a big tarp and it can be difficult
working with large pieces of slippery fabric. It can also be
difficult to deploy a large tarp such that it doesn't sag
excessively, collect water and/or flap in the wind. I have learned
quite a bit about tarps recently... enough to realize that there is a
lot more that I don't know. I would study the tie-outs on Oware's
diagrams and decide what you think you need for your applications,
especially the tie-outs on the side panels. Typically, I think most
tarps use a flat-felled seam for joining two pieces of material and
then use a double folded, or rolled, hem along the perimeter. It is
best to keep the folds on the inside surface of the tarp so they are
less likely to collect rain water.
How many different configurations do you normally use with your 10x10
tarps? (I'm talking A-frame, flat, etc.) If you haven't worked with
silnylon tarps before, you may not be aware that they are not as
waterproof as other tarp materials and they do stretch, especially
when wet. The waterproofness shows up under VERY HARD rains and
results in what is sometimes described as a 'slight misting'. For
most of us this hasn't been a problem because (1) these hard rains
are very infrequent, (2) the rain usually doesn't stay at that
intensity for very long and (3) most of our water sensitive gear has
DWR finishes that handle the misting without noticable 'wetting'.
The stretching is another matter. First, you can minimize it by
using low stretch guy-lines so they don't add to the problem. (Nylon
guy-lines typically stretch a lot.) Second, you can use some shock
cord with the guy-lines to help maintain tension. (Be very careful
of the sling-shoot effect when using shock cord and stakes, it can be
very dangerous if you 'launch a stake'. I posted a picture of how I
utilize the shock cord here: http://tinyurl.com/2wafe ) Third, you
can incorporate a taut-line hitch in the guy-line so that re-
tensioning is easier.
Good luck and please let us know what you end up with.
- --- In firstname.lastname@example.org, "billmoody1" <billmoody@n...>
Another source for hammock ridge-line seams is http://thru-hiker.com
Check "workshop". Anyone remember post #2505 "Sling shot tie-outs"
shock cord alternatives? To help waterproofness of silnylon, Ed
Speers's book suggests sprays available in camping stores. Oware
usa also suggests using stronger materials for large groups, esp.
boy scouts or other youths that might have a different view of the
meaning "handle with care". When adding tie-outs, Ray Jardin
emphasizes not sewing through the single layer of nylon, but only
into the hems or center seam.