In section 4 of how 3dl sails are made it said that the mylar film is joined at seams do these just disappear? or can they still be seen while sail is flying.
They are really hard to see and you have to look closely. Not what you really would call seams. The mylar film is quite thin, and as I mentioned in an earlier post, the film is in sections as it wouldn't be viable to make the whole sail as a single film (but I am sure that Norths are looking into this). The seams are essentially just a way to join the whole sail together, but wouldn't meet the definition of broad seaming in creating shape, as opposed to holding the shape made by the kevlar/carbon yarns.
