Thank you Hammer and Dave M for your time and trouble in response to my query. Very useful information from you both.
And thank you for putting me right! 😀

Ihpen, Are you worried about cutting & hemming, That is why you though of non rip. As Dave said if you want a scale appearance you need a cloth, tightly woven cotton.
My method is easy just takes a little time. When cutting out Have the warp of the cloth parallel to the leach (back edge) of the sail. Cut 1/4" larger all-round. I have an old steam Iron which I use to Iron a hem with practice 1/8", but to start 1/4" will be fine. Then I paint PVA ( not to thick) glue in under the hem and Iron again. I clamp a section of sail to a board with the bolt rope over the hem & start stitching. I do this watching TV. I mark the seams with pencil then apply a very thin wash of acrylic grey paint on white sails as in photos.

HI Ihpen
Your gaff rigged model would not really suit rip stop nylon, which is more suited to racing type yachts.
I used cloth purchased from Chris Brown Models for my Cariad but I have also used bed sheets purchased from Aldi, cut up dyed and sewn.
I suspect this is similar to Hammers's suggestion but will produce a more scale apperance and really catches the wind. 😀

The material I use for scale models is called "ticking". Originally used for lining pillow cases, tightly woven to stop feathers pocking through. So ideal for stopping wind. Also takes dye better than some nylon . 🔨