I’ve made several IOM sails using a ‘Claudio gadget’ where a flexible beam is used to build the broadseam into one of the panels. When I made sails from thin ‘cellophane’ from the florist (flimsy stuff to use but it’s cheap) I found that quite often the broadseam would wind up lop-sided, with most of the camber being built into one panel and hardly any on the other side. I think this is because the seam itself is relatively stiff (two layers of film plus a layer of adhesive) compared with the panels and so it resists being bent in the plane of the sail and does not curve when released from the gadget to allow the broadseam to be ‘shared’ equally with the other panel.
So I tried making a gadget with two flexible beams instead and found a big improvement as each panel gets the same amount of broadseam. As a bonus I also found it much easier to stick the two panels together without kinks or wrinkles - by far the trickiest moment using the usual gadget. If you’d like to try it I have attached instructions. (I’m assuming you know how to use a regular ‘Claudio gadget’ - if not search on this forum first and read up on it).
