Tarp Pitching Woes

Take a look at this Jacks'R'Better product.

http://216.83.168.206/index_files/Self%20Tensioning%20Lines.htm

Pitch it as tight as possible when first pitching. Really tight.. Scarry tight…

If you position the front pole at a slight angle leaning forward, at night you can reach out easily and shift the pole bottom (tip) forward to straighten it up and thus make it about an inch or two taller and that can take out some slack.

I like to point the trekking pole tips to the ground and seat them. -A bit less less potential to skitter or slide out if the tarp gets hit with a big gust that lifts it a bit. I use a girth hitch of the guyline to the trek pole handles.

If you are iffy on pitching it really tight, perhaps you are concerned that the stakes will pull out under the strain. In that case bigger/longer stakes or something to better secure the stakes/guylines is needed.

All tarps and tents stretch a little at first as the stitching eases into its natural stretched position.
And all nylon tarps and tents stretch as the nylon absorbs water – which happens overnight due to your own insensible perspiration, dew (whether you notice it or not), and/or precipitation. This is a permanent feature of nylon shelters. Would that manufacturers provided lightweight polyester material. Polyester does not stretch, and some good tents have been made of it. The up side of nylon's stretch is that nylon's strength is in the stretch; it absorbs wind shock and other abrupt stress loadings.

Yes, elastic guy lines will keep your tarp from sagging. I make loops of 12 inches of round waist cord elastic through the pull-outs, and attach the guy lines there with taut line hitches (prussic knots) so they are easy to reach and adjust without getting out from under the tarp. The idea is to tension the elastic about half way so it has enough pull to keep the tarp taut through the night as it absorbs water while leaving some spare stretch to absorb wind shock or the incautious step when I venture out in the middle of the night.