I had a chance to try out the Mountain Laurel Designs trailstar shaped tarp. As advertised it is easy to set up. Basically you pin four corners (ideally the four that have short leads), slip the walking pole or hiking stick in (handle side up) and stake out the fifth line (using a clove hitch to tie it to another hiking stick). Voila – it is up.
That said, setting it up efficiently for the wind is a bit harder. Basically you can easily set any three or four corners taught, but there is always one that is floppy. However, basic trigonometry comes to the rescue. The tarp is made of isoceles triangles that are about 76″ (193cm) on the long sides and 82″ (208cm) on the short side. Pitched as a perfect pentagon, i.e. one that is inscribed on a circle, the radius if the enclosing circle is 104/sin(2 pi/10)) or 176.93 cm. The ideal height of the pole is then found by Pythagoras’s theorem to be about 78 cm. (I’m using cm here not just because I like metric, but because most hiking poles are marked in cm). This will be slightly shorter than ideal because I’ve left of the lengths of the guy lines and linelocks. So if you want all the corners on the ground and a more or less taught tarp, the pole height should be a little bigger than 78 cm. (for a really tight fit use all ten places that could be staked out).
I tried adjusting the line locks from inside and found them less than easy to adjust from the inside. It probably takes some practice. It was fairly windy on this campout and I had to adjust the pole height (hence the calculation on what it should be). This would have been a real pain in the rain. I didn’t have a chance to try it in inclement weather, but am not sure that the lifting a corner to get out is not the most convenient approach to egress. Certainly if you can use a pole to keep one end high, it will be better.
As delivered from MLD it comes with seam sealer and all the line needed to set up lines on all ten points. The five corners already have lines on them, with one of the lines longer for use as an entrance. With a little bit of practice it will be as secure as any tent.
One reason I became interested in the effects of the wind has to do with its effects on my sleeping – the sleeping quilt I used was a bit chilly at 42-45F. So I’m reconsidering if it will be warm enough for Philmont.