Tuesday, 28 February 2017
Sewn Seized Eye for Rigging
Sail Delmarva has covered a topic which I had heard about but had never had the chance to try out. I love the idea and actually have had very good success with a similiar idea. You can read about that at the end of Sail Delmarva article here on sewn/seized eye. Besure to click over to Sail Delmarva's site for other great articles on boats, sailing, and boat products. Without further ado, Drew starts out with a prologue......
Can't Splice Old Line? Try a Sewn Eye.
Splicing is the gold standard for forming permanent eyes and joining lines; unfortunately used double braid generally lacks the flexibility required for splicing; the cover won't open and the core won't slide. Knots are a standard solution and work in most cases; yes, there is some loss in strength, but lines generally die from chafe and I can't remember having one fail at the knot, other than in testing. But sometimes there simply isn't enough space or a knot will snag.Seizing is traditional and just as reliable as ever. I've seized a dozens of eyes over the years and never had a failure. I helps if you cover them for UV and chafe protection, but if the seizing is double layer like the old days, the outside layer is the UV protection and the inside layer holds the load. But seizings are long and stiff and can hang up, since the tail is neither covered nor tapered. So occasionally I use a hybrid sewn/seized eye. This isn't an idea I dreamed up, it is an old one that I read of many years ago in theNew Glenans Sailing Manual. They also speak of stropes, the precursor to soft shackles.
First I remove about 1 1/2 rope diameters of core. This will allowed the end to be stitched down to create smooth taper. The New Glenans Sailing Manual calls for 3 1/2 to 4 rope diameters of core and I've got 4 1/2 diameters without counting the taper.
How much stitching is enough? Most whipping thread is about 50- to 60-pound test (I use 90-pound Kevlar, just because I have it), and doubled that suggests about 25 stitches on each side to reach 5000 pounds. Sure, it is not loaded in-line, but most of the load (about 65% in testing) is actually carried by line-to-line friction, just as in a seizing. Also remember that due to friction of the eye around the shackle or fitting, the free end is only carrying about 35% of the load. The results is that the stitching is only carrying a working load of about 1000*0.35*(1-0.65)=122 pounds and a line failure load of about 610 pounds (assuming 5000 pounds for aged 1/2" Stayset); not nearly as demanding as you would guess and as usual, the splice is stronger than the line. The stitching is scattered so that some are in every part of the core.
After stitching I add 2 seizings for good measure. The throat seizing is the important one, as it keeps the first row of stitches from getting over loaded.
Then cover it with something for UV and chafe protection. Heat shrink is fast and nice. tape works too, if you check it annually. Webbing would be very good in some severe applications.The New Glenans Sailing Manula only calls for 3 1/2 to 4 rope diameters and I've got 4 1/2 diameters without counting the taper.
Just the money saving trick I need today. Just recently I needed a 75-foot sheet for a new bit of rigging and I had a perfect bit of double braid salvaged from a halyard that had suffered chafe in one spot. I particularly enjoyed this lower cost (zero) solution since I am not completely certain of the final rigging. Spending money is bad, but spending money on something you might decide to change is worse.
Sooo, how strong is this? Click on over here to read about Sail Delmarva testing of the sewn and seized eyes
Demonstrated here is just one seizing to make an eye. We usually use four with a thimble to help form the eye. We then wrap the wire in self wrap tape to protect the wire.
Here to the right you can see the tool ready to cinch down the wire to form the seizing.
To the left is the finished product. We usually use four of these to seize for an eye.
To the right, the eye is starting to be formed. By the time you get four of those on, the eye will be as strong as any that has been spliced. Be sure to cover the wire with with something for chafe protection. Heat shrink is fast and nice, tape works too.
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