I think hanks made using YKK LB10FR micro-buckles are the best available. Sadly the minimum quantity I had to buy was 100, but I have used most of them over the last few years.
This (above) is how I attach them (I expect there are other ways). I used to use soft sailcloth or spinnaker leech tape, triple thickness and zig-zag sewed to make a flexible strip of material just under 10mm wide. You need a strip 40mm long to fix a socket, you need a strip 50mm long for a plug. Currrently I am trying polyester webbing 10mm wide, this is thicker than sail cloth, so the plug strip needs to be longer - I am currently trying 60mm. I also tried 12mm webbing, but it was too wide.
First remove your velcro, or screw on, hanks.
I do sockets first and put them on the starboard side of the sail. Mark 10mm from the luff with a pencil where the old hanks were (you should be able to see the holes from the sewing or the screws). You want the edge of the socket to be 10mm from the luff (edge) of the sail. You use a 40mm strip looped through the socket. A bit fiddly, but use the needle on the sewing machine to hold in place, then sew. Go up and down a few times (using the reverse button). It needs to be strong, so maybe do a row at the end and near the socket. I use triangular cross section needles (Schmetz Leather 130/705 110/18) and polyester thread. You can try zig zag stitches, but I find a normal running stitch works OK. That also means you can have the needle offset so you can get it close to the socket. Needless to say, you want the body of the sail off to the left of the sewing machine, so it does not crumpled. Have the sail the correct way up, start with the top hank and work down.
Then do plugs. They go on the port side of the sail level with the sockets. Once again mark 10mm from the luff with a pencil. This time the end of the loop of the 50mm sailcloth/60mm webbing is 10mm from the luff of the sail. You should be able to sew the plugs on without the sockets (on the other side) getting in the way, but you might need to fold them out of the way. This time you need the sail upside down. Start with the bottom hank and work up.
That's it. My aim was to get my 2.5mm wire forestay as close to the luff of the sail as I could.
