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davebrown
04-17-2012, 10:30 AM
http://4.bp.blogspot.com/-dUXgU0Aa2-U/T4xmA1nSTaI/AAAAAAAABJA/uokxH5GuBfA/s1600/photo-719224.JPGI
I borrowerd this photo from the NorEaster Dory thread because it has, by funny coincidence, a photo of the very page in my sailmaking manual that I was looking at as I was pondering the last section of our Coquina sails. The sails were done from a SailRite kit and the instructions appear to place the grommet exactly as the above illustration, on the left, which is say, the grommet pierces and ultimately cuts through the stitching. Clearly that lops off and terminates the stitching, but wouldn't it be smarter to put the grommet right on the edge of the stitching, raised an 1/8", so that it doesn't cut through the zigzag?

I appreciate how the illustration of the handsewn rings, on the right, reflects the real sailamker's art, and they look stunning. I could go to the trouble of handsewing like the rings on the right, but the same text says, later in the work, that the handsewn rings are not much stronger, if at all, since the fabric tears either way. Opinions will be appreciated. The author talks about testing the two different rings by tearing them out with a tractor, while tied to a tree. What a test!

wizbang 13
04-17-2012, 02:10 PM
I do em differently. I machine stitch nylon webbing over a metal ring, or even a cut piece of pipe. Dingy sails or cruising sails, same but different. Nylon webbing hardly fights the needle. It is easy to sew through.
My sailmaking is as funky as every thing else on my boats. Practicality trumps "beauty" every time in my world.
I appreciate time consuming craftsmanship on OTHERS boats, though.

Timotaeus
04-17-2012, 04:46 PM
BTW this page is from The Sailmaker's Apprentice by Emiliano Marino.

Ian McColgin
04-17-2012, 05:08 PM
The pressed ring seals that part of the stitching cut in making the hole for it and forms of itself a more continuous binding between the layers than any stitching could do. In short, no problem.

Timotaeus
04-17-2012, 06:27 PM
I think we can all agree that the 'bumper stress test' is a stunt. It does make you wonder, Are sewn grommets strong enough for sails? Gosh, it seems to me that they probably are for me. I'm already heading back to shore if I got to worry about my grommets! But I'm not going to sea, and if I was, it wouldn't be with sewn grommets to be sure! but I'm not in a hurry to get anywhere, at least nowhere to be found.
Regards, Tim

Todd Bradshaw
04-17-2012, 06:37 PM
It doesn't really matter if you cut the stitching. The flange and teeth on the ring or grommet (or stitching and ring if you hand-sew one) will cover the loose thread ends and keep them from going anywhere and they are what is holding everything together once they're installed. The pressed ring on the left is different from a grommet. They're installed with a 30 ton press (like a bearing press) which most folks don't happen to have on hand. A spur grommet which you can hammer in with the propper setter, is quite strong, but nowhere near as strong as a pressed ring or a hand-sewn ring. His tear test was a pressed ring vs. a hand sewn ring. In a test between a grommet and either of those, the grommet would fail (or at least deform badly) before the corner ever tore out and very long before the pressed or sewn rings would. Even so, on small-to-medium sails or other fairly high-stress applications like trampoline lacing holes, spur grommets generally work fine once you get up to size #2 or larger.

The fitting on the right is actually a cringle. Small anchor holes are made in the sail and a brass thimble is woven tightly up against the sail's edge, with the lashing passing through the anchors and around the outside of the thimble, rather than the thimble being put through the cloth. This requires the edge to be roped, so that there is something large-diameter for the near-side edge of the thimble to ride against. Cringles are also quite strong if installed and anchored well. This is a cringle. The edge roping passes uniterrupted around the corner, twine lashings connect the small anchor holes together and a single strand, unwound from an extra chunk of the same bolt rope line, is woven back and forth between two of the anchor holes. This is a little sail, so the anchors are just #000 (tiny) spur grommets. On larger sails, they would usually be sewn rings. Lashing them together spreads the stress over a greater area for more strength. The lashing holding the thimble is made undersized without the thimble in place. Then the loop is stretched with a fid and the thimble hammered in before the lashing contracts. This is easier said than done, so I ended up building a set of special cringle fids that install them neatly and then come apart.

http://webpages.charter.net/tbradshaw/Sails%20and%20Plans/tack%20corner%20copy.jpg

http://webpages.charter.net/tbradshaw/Sails%20and%20Plans/cringle%20fids.jpg

Regular sewn ring with hammered-in brass liner installed
http://webpages.charter.net/tbradshaw/Sails%20and%20Plans/corner%20detail%202a%20copy.jpg

A webbed-on round or D-shaped stainless ring isn't very traditional looking, but they are also very strong and most webbing sews easier with a machine than you might think. You can even buy stainless clew plates with slots for the webbing. It is a good idea, however, to use Dacron webbing, rather than nylon (less stretch and much better UV resistance).

davebrown
04-18-2012, 10:33 PM
As always, the professionals on this forum are just stellar. Thanks for taking time to write, Todd. I am not too concerned with looking traditional. I like the idea of doing the webbing. My wife, who is manning our somewhat outgunned machine, thinks the webbing will be a simple and very successful end to our endeavor. I have one more question and I will start a new thread on it.

Todd Bradshaw
04-18-2012, 11:20 PM
Webbing works. There are various ways to do it, but I usually cut a half-circle-shaped notch in the sail's corner to set the ring into and then use three strips of webbing about 8" long, middled and folded over the ring and running up both sides of the sail. Use a line of seam tape on the back side of the webbing to hold in in place with a strip of webbing up either edge of the sail and one bisecting the corner angle. Sew each one down well and then hand-sew across all three with heavy twine very close to the ring along the cut-out. I always had better luck with round rings than D-rings (which often want to twist).