Well, I made it to Broken bay, 35 miles in a 20 knot following wind and 2 metre seas. As expected, my homeward bound stitches failed due to the weakness of the surrounding cloth and a hole about 300mm x 75mm appeared, but my very strong boltrope/ leech tabling held the sail together and the sail did not tear right across, as I feared it might.
The good news is that this appears to be the only seriously weak patch in the sail, an area of about 400mm x 100mm, near the leech, just below the peak, so I won't have to scrap the sail after all! Just a panic attack when it happened at dusk yesterday, on the eve of a passage. It may be caused by the tension on the THP, but I'd be surprised if it is, as my Arne type sail does not seem to have very high loads on the THP and my top panels are almost flat cut.
It looks like chafe, but that is also puzzling as there are lots of other places in the rig, such as where the sail is pinched between the mast and the battens, which I have always worried about but which seem fine. I have been wrapping a preventer around the bundle near that point and hauling the sail bundle outboard when at anchor, tensioning it against the sheet, to stop the bundle squeaking against the mast when rolling in a swell (don't you hate that!) and also to expose the solar panels. Perhaps this has somehow pinched the sail and worn that patch tissue thin. Whatever, I will just glue a big patch on either side and carry on.
I am pleased to say that the rest of the sail appears to have plenty of life in it. Odyssey is a light, stretchy material and my cambered panels set nicely in a light breeze, but I have had trouble with eyelets pulling out if it and a few straight-stitched seams pulling apart. I have reinforced these areas with extra stitching and it seems to hold together. (Next time I'll use strops instead of eyelets).
For offshore work I'd like a sail with vertical, triple stitched seams and good reinforcing patches. That way, if you get a few holes here and there they won't matter. With my sail, where each panel is made up from one piece of cloth, if you do get a hole it can take out the whole panel. I like 5 oz Dacron, as it is strong and chafe resistant, but I have read that it is more subject to chafing where it is pinched on a junk rig than softer materials. I am still a babe in the woods with this rig, so don't have any firm opinions. I do have a beautifully built flat Dacron sail on board which I will probably refit if my cambered sail falls to bits, which would give me some experience with this material. But I love the performance of my cambered sail so won't change it unless I have to.