Hi Jan,
I’ve replied to your post here.
The polytarp I used for my experiment has held up well considering it’s only held together
with gorilla tape and single stitching. I only needed it to last long enough to establish whether
SJR would be viable for both sails on a Schooner so didn’t take any care in the construction.
I had hoped to have made the new suit of sails by now using posher cloth but haven’t had the time, however I’m getting on with it now.