Wednesday, February20, 2019

Y Sheet

Soft Shackle Version


My old friend the dual soft shackle version 1 has found a new use. It is common practice to use some kind of tail on an asymmetric spinnaker to keep the clew away from the rigging. One version is called a Y-Sheet. It connects to eye splices in the sheets and extends to some kind of connection to the clew either with a knot or a shackle. This article shows how to use a soft shackle type arrangement and not only avoid the strength loss that you would get with a knot, but basically doubles the strength of the line used for a penalty of a small increase in the length of the rope you need.

This photo is a what I call a double soft shackle version 1. This article goes through making one 30 inches long for use in a Y_Sheet. The picture shows the main eye around a pair of spinnaker sheet eyes and the soft shackle eye attached to a stopper knot that is luggage tagged to the spinnaker clew.


A traditional Y-Sheet would take a section of line and put an eye splice on each end. The finished Y-Sheet would be as strong as the line it was made of. In this example I am making a 2.5 foot y-sheet. If using Amsettl, the splices would take about a foot of line each so the line you need would be about 5 feet. With this design, just over 6.5 feet but what you end up with is significantly stronger than the line it is made of.

The design

This y-sheet will be 2.5 feet long with a 6 inch loop on one end and a soft shackle eye on the other. It is made of 5/32 Amsteel that has an average strength of 4,000 pounds. The stopper knot will use 1/4 inch Amsteel with an average strength of 8,600 pounds. We know from testing that the stopper knot degrades the line strength by 50% which gives a strength of 4,300 pounds for the stopper knot. The soft shackle starts out at twice the line strength or 8,000 pounds but is degrades by the turn radius about the stopper knot by 65% for a net strength of 5,200 pounds. That is more than the stopper knot and much more than one would get with bowlines of 7/16 line (3,300 pounds).

In THIS article, Elliott / Pattison Sailmakers say this: A "Y" sheet is widely used and consists of two sheets connected with a single short tail that is tied to the sail with a bowline. This reduces the drag during the gybe.

The length I wanted to make was 30 inches overall of which 6 inches was the eye that goes through the sheet eyes with a luggage tag. With 5/32 line the eye is 38 diameters. I could have gone as small as 23 diameters or 3.6 inches, the same as what I tested on version one of the Double Soft Shackle. The calculation of the amount of rope that is needed is to add the overall length to the length of the large eye and multiply by 2.22. In this case that is (30 + 6) * 2.22 = 80 inches. The next setp is to make a series of marks on the rope.

Make marks 6 inches from the end (for the 6 inch eye). The next mark is back 6 * 2.22 inches from the end or 13 1/3 inches. Then make another mark 3 strands beyond that mark. These two marks close together allow room for the burmmel that will be formed at that point. Do this on both ends.

The soft shackle eye is in the center of the finished piece but one side needs to be longer at this point because it gets shorter when the other strand is buried inside. This bury is 24 inches long in this case (overall length less the large eye size). The shortening is 0.22 * 24 or about 5 1/4 inches. Overlap the two strands with one that length longer and fold the rope around something larger than the base of the stopper knot in this case two pieces of 1/4 inch Amsteel. Mark the line on each side where the two sides come together. That will be the soft shackle eye. Mark the longer one with a line to identify it more easily.

Prepare the first part of the taper by marking starting 6 diameters from each end and marking every other strand, right and left, for a total of 6 strands as shown. In this case, 6 diameters is just under one inch.

Pull the strands out at the marks.

Cut them off. By the way, THESE shears are amazing for cutting Amsteel and similar lines. They have micro groves so the line does not slip and basically cut through Amsteel as easy as cutting wet spaghetti with kitchen shears.

The best fid I have found is a section of stainless rigging wire folded in half with the ends tied together so you can pull on it easily. Thread this on the longer leg from the mark 3 strands from the second mark up until you get to the soft shackle eye mark with the marking showing this is the longer strand.

Place the opposite end in the fid inserting it about half way to the first missing strand. This will allow the rope to double over and be just one diameter thick which makes it easy to pull through.

Pull it all the way through.

Next insert what is the cover through the core. This will lock the core.

Pull it tight.

Now we are going to form the eye. The idea here is that both ends are buried in the opposite leg of the eye. Start with one and thread one of the fids, in my case I used a shorter one, from the crossover to the 6 first mark (6 inches in this case). Insert the tip of the other end in the fid.

Insert the tip of the other end in the fid.

Pull it all the way through.

Now do the same thing to the remaining end. Note I use a small knitting needle to lock the end I just did so that it doesn't accidentally work its way back into the cover. I also had to bend the fid to allow it to get to the mark. Finally, insert the tip of the other end and pull it through.

Pull both ends firmly so that the crossover at the outer end of the eye is snug against itself.

Cut off the top at an angle, anything more than 45 degrees is fine. This is the final taper.

Milk everything smooth to completely bury the cores in their respective covers.

Lock stitch the crossover region. Start in the center and do 7 "S" stitches, reverse and do 14 at 90 degrees and 7 back toward the center. Have the final stitch exit near the first one and tie them together and set the knot with a lighter or torch.

Back some distance, lock the soft shackle with a small needle and test the soft shackle to see that it is a comfortable fit over the stopper knot. Move the lock until you have a length you are happy with.

To make the stopper knot, use the calculator from the Soft Shackle Howto, measure off a piece twice the length of the first mark. Double the line over, tape it at the fold, and tie a diamond knot using the two ends. Lock it by placing the ends in a vice and pulling on the loop with a lever of some kind. I use a hammer with the had as the fulcrum and the loop on the handle near the head.

Lock stitch 7 down and 7 back and tie the ends off.


To use it, luggage tag the stopper knot to the clew of the spinnaker and use the soft shackle eye to attach it. Note I inserted some thread through the eye to make a pull to open it easily.

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