Alright, here we go. This picture shows one half of the shelter - using 1.85m wide material you can get a complete half from the width, meaning you only have to sew one seam. On narrower stock you will have to sew more seams. And please note these are the actual final dimensions of each panel - you must add on an allowance for the seams (12mm in my case)
Useful tips........to layout you need a large flat area. I used a 2.1m long piece of wood as a trammel to lay out the panels - drill a hole at one end for a pencil or marker. Then measure from the centre of that hole and drill 1.5mm holes at all the necessary dimensions (i.e.1550mm, 1840mm). I marked on the base line of one panel then placed a small nail through the predrilled hole in the piece of wood through the material at a corner and then marked an arc using the pen. I move to the next corner, alter the position of the nail and make a send arc - where the two overlap is the third corner of the triangle. On such large panels this method of marking out is very useful.
Sew the main seam first, then do the bottom edges last. Sew on a reinforcement patch at the peak of the tarp BEFORE sewing the main seam. Otherwise you will need to glue this patch in using seam seam or a suitable adhesive.
To sew the main seam pin it out along the length and then roll up the surplus material and peg it into a manageable bundle so you can concentrate on sewing the seams without worrying about multiple square meters of material flapping about/getting stuck/pulling you off line.
Reinforce the area around the peg outs with either a second layer of material or a second layer of something tougher. Do this before sewing the seams around the bottom edges of the tarp.
The catenary curves along the bottom edge are not totally necessary - you can just sew a straight edge. I made an arc 90mm high at the centres and this made for a happy result. Do a quick google on catenary curves to see if its worth the hassle to you.
You can sew a loop on the front "beak" of the tarp for a guy line or you can just tie the guy line to the pole you are using.
I hope this helps - any questions ask away. I offer this plan to forum members to make their own, not to be copied commercially.
Cheers
Phil