Cloth sails are nearly impossible to make on models scaled smaller than 1:24, For the smaller scales they look like they are made from thick rope in many cases. The below photo popped up while looking for something else so I downloaded into CAD and scaled it to full size. The piece itself is 70mmX138 according to RMG. The average thread count (TC) looks to be 25 to 27 per inch. Appropriate TC cloth for a model is impossible with existing cloth commonly available today, even the finest Turkish cotton materials. I thought this sample of actual sail cloth was an interesting piece.
Allan
Allan