Sew This Jib Sock to Protect Your Furled Headsails

If you install a cruising furler like I describe in Headsail Furlers For the Trailer Sailor and you don’t also add sacrificial cover strips to the leech and foot of your headsails, those edges of your sails will be constantly exposed to UV sunlight and the weather and will deteriorate much faster than the rest of the sails. Having a sail loft add sacrificial strips can be expensive, particularly if you have it done it to multiple sails, say, your jib and a genoa. An alternative solution is to make this DIY jib sock. You can use it to protect whatever sail you have on your furler and at a fraction of the cost of sacrificial strips.

A jib sock (also called a snorkel) is a tube of weather resistant canvas that can be closed around a furled sail with fasteners like zippers, twist locks, or hook and loop tape. When it’s time to sail, you simply remove the sock and unfurl the sail as usual. At the end of the day, you hoist the cover up the forestay and furled headsail using a spare foredeck halyard while a crew member on the foredeck closes up and secures the cover. One person can do both jobs if you use the trick I explain at the end of this article.

This sock requires an unused halyard to hoist it up the furled headsail. If you have a cruising furler that uses the jib halyard at all times, you will need another halyard for the sock. You can use a spinnaker halyard if you have one. If you don’t yet have a spinnaker halyard, this is another reason to rig one like I describe in How to Rig a Cruising Spinnaker in 4 Stingy Stages. If you have a different type furler that doesn’t use your jib halyard, you can use that halyard for the sock.

This is a relatively easy project to make. Most of the sewing is in straight lines and there are only a few pieces. An industrial or walking foot sewing machine is not necessary even though one does make the job easier. You can make this project with any home sewing machine that can sew through several layers of canvas or denim. You can purchase all the materials you need à la cart from Sailrite. You can find a materials list for a sock up to 29′ long at the end of this article and I provide a dimensioned drawing that also has the materials list on my Downloads page.

Let’s get started!

1. With your largest headsail attached to the furler and furled, measure loosely around the thickest point of the sail – we’ll call this dimension A. Also measure the total length of the furled sail from the end of the halyard to the top of the furler drum – we’ll call this dimension B. These two dimensions will determine the finished size of the sock. You can also use it with your smaller headsails.

2. Unroll the fabric and cut two strips the full length but make the width equal to A + 6″. For best results, use a hotknife. You will join the strips end to end in step 4.
Note: Depending on the width of the fabric that you buy, you might have a lot of fabric left over. You can reduce the waste by buying less fabric but joining more pieces end-to-end to achieve the same length. These instructions minimize the number of middle seams to just one. On the other hand, more leftovers means you can make other projects for almost no cost. Think storage bags or some of the other sewing projects on this site.

3. If your fabric has a coated side, mark that side temporarily as “IN” and the uncoated or right side as “OUT.” A soap stone pencil works well for this or you can use an ink pen on masking tape.

4. With the OUT sides of the strips facing each other, sew them end-to-end using a semi flat felled seam as shown in this video. You should end up with one strip B in length. If you’re unsure how to do any of the other sewing in these instructions, check the Sailrite website, they have lots of videos available for free.

5. Cut the cover to a length equal to B + 4″ + 1″ for every 10′ of dimension B. For example, if dimension B = 25′, cut the cover to 25′ + 4″ + 2.5″ = 25′-6½”. You can cut all of the excess from one end of the cover or cut half of the excess from both ends. The location of the middle seam is not critical.

6. Sew a 1″ double hem across both short edges on the IN side of the cover. For best results, use Seamstick basting tape to make your edges straight and to hold the fabric in place while you sew.

Picture 1: Applying Seamstick basting tape at the hem fold
Picture 2: Sewing the folded hem

7. Now for the most complicate step in this project, installing the zippers. But if you keep the OUT side of the fabric facing the outside of the zipper tapes and the zippers oriented so that they close from top to bottom, the sewing is easier than it seems.

This design uses two zippers, one long and one short with a 6″ gap between them to allow the jib sheets to lead from the clew to the lead blocks as shown in this picture. This lets you leave the sheets attached and ready to go.

Picture 3: Sheets lead out through the gap between the upper and lower zippers. Cord tied to the zipper pull holds the slider when hoisting the sock single-handed.

Separate both zippers into halves. Apply Seamstick tape to the outward facing side of one half of the long zipper and flush with the zipper tape outer edge. Align the end of the zipper tape to the top end of the cover with the slider pull tab pointing toward the bottom of the cover and affix the zipper tape edge to edge on the OUT side of the cover and press the basting tape down along its full length.

8. Repeat the preceding step to apply one half of the short zipper below the longer half, leaving a 6″ gap between the tapes. The bottom end of the short zipper should align with the bottom end of the cover.  If necessary, adjust the position of the zipper tapes to align their ends with the ends of the cover. You might need to trim the bottom end of one or both zippers and sew on fabric stops to make them fit.

9. Mount a zipper foot on your sewing machine and sew a continuous row of stitches through the assembly 1/8″ inside the edge of the zipper tape. Always start and end a row of stitches with several reverse stitches to lock them in place. At the end of one zipper tape, continue sewing through the gap and continue down the other zipper tape.

10. Fold the cover onto itself along the zipper teeth so that the zipper tape is now on the IN side of the cover. Use more basting tape to hold the edge in position, if necessary. The fold should be even with the zipper teeth so that the two edges of the cover will meet neatly to enclose and protect the zipper from UV exposure.

11. Sew down the fold with another row of stitches along the edge of the basting tape closest to the zipper teeth. Be careful to not sew too close to the zipper teeth or the slider will not pass. The outside of the zipper should look like picture 7 below.

Picture 4: Sewing the second row of stitches in the zipper

12. Repeat the preceding steps to baste and sew the remaining zipper halves to the opposite edge of the cover. All ends of the zipper halves must align together perfectly or the zipper will be difficult or impossible to close.

13. With a hotknife, cut three 6″ long pieces of 1″ webbing and fold them in half lengthwise to form loops.

Picture 5: Cutting webbing with a soldering gun and rope cutting tip on a sheet of glass to protect the table

14. Sew the cut ends of the loops to the IN side of the cover– two loops at the bottom of the cover as shown in picture 7 and one loop in similar fashion in the middle of the top edge of the cover as shown in picture 6. You will use the top loop to hoist the sock while keeping the zipper on the underside and the bottom loops to secure it to a cleat, stanchion base, or whatever is close.

Picture 6: Webbing loop at the top of the cover for connection to a halyard (spinnaker halyard, in this picture) for hoisting
Picture 7: Webbing loops at the bottom for securing the sock. The white paracord is tied to a snap shackle attached to the furler underneath and is not part of the cover.

15. Tie one end of the paracord to the top loop. You will wrap this snugly around the sock as shown in the picture at left to prevent the sock from fluttering in the wind or oscillating around the furled sail, causing chafing. When you determine how long the paracord needs to be for your sailboat, cut off the excess and tie it to the upper zipper pull tab. You can use that to hold the pull tab down near the deck while you hoist the cover up the furled sail single-handed. This process is described below.

16. Optional. This step isn’t necessary for the function of the sock but it makes it much easier to stow and deploy. Without it, the two paracords are loose and will tangle when stored. For an easy storage solution, sew a roughly 6″ x 6″ pocket on the IN side of the sock at its top near the halyard loop where the long paracord is tied. Before you stow the sock, loosely wind up the paracords and secure them in the pocket with a small patch of hook and loop tape on the inside of the pocket opening. Then you can fold or roll up the sock without any cords hanging out. See the sock drawing for more about the size and location of the pocket.

17. Optional. You can stow the sock folded or rolled up but for maximum convenience, make the two bottom loops from loop tape instead of webbing and sew patches of hook tape onto matching locations on the cover so that it is self-securing after you roll up the cover.  You can also stow the cover inside a nylon bag with a drawstring to keep it from fouling during storage.

How to hoist the sock

Hoisting the jib sock by one or two crew members only takes a few minutes. With a little practice, you can do it in under a minute.

  1. Lay the sock in a loose pile on the foredeck near the furler with its outside facing down and the top of the sock on the top of the pile.
  2. Connect an unused foredeck halyard to the top loop of the sock.
  3. Wrap the top of the sock around the furled headsail and start the upper zipper slide with the zipper on the underside of the sail.
  4. If you have a crew member to help, have them hold the upper zipper pull tab stationary and guide the sock over the furled headsail while you hoist the sock to full height. If you are doing this alone, tie the loose end of the short length of paracord that you cut in step 15 to a deck cleat or pulpit stanchion base to keep the pull tab within reach while you stand at the mast or in the cockpit and hoist the sock to full height. You can guide the sock over the furled sail at the same time if you stand on the foredeck and pull the descending part of the halyard in front of the mast.
  5. With the top (long) zipper fully closed, start the bottom (short) zipper below the jib sheets and close the rest of the sock around the bottom of the furled headsail.
  6. Wrap the long paracord (attached to the top of the sock) snugly around the sock 5-6 times and secure the end to a deck cleat, stanchion, or other stationary hardware. If you don’t do this step, tie one of the bottom loops to deck hardware with a short piece of cord.

How to remove the sock

One person can remove the sock in about one minute.

  1. Unwrap the paracord from around the furled headsail and untie the bottom loop, if necessary.
  2. Unzip the lower (short zipper).
  3. Uncleat the halyard attached to the sock and let the sock slide down the headsail from its own weight.
  4. Unzip the upper (long zipper) with one hand while you pull the sock down with the other hand.
  5. Disconnect the halyard.
  6. Wind up both paracords and stow them inside the sock pocket.
  7. Roll up and stow the sock in a dry, well ventilated space.

Materials list

  1. 5 yards heavy duty canvas (Sunbrella, Top Gun, or equivalent)
  2. 2′ x 1″ white nylon webbing
  3. 72″ #10 zipper
  4. 222″ #10 zipper
  5. 3/8″ Seamstick basting tape (optional)
  6. 1″ x 1/2″ hook and loop tape (optional)
  7. 35′ paracord

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4 Comments Add yours

  1. JimF says:

    What type (material) and size of thread do you use? Also what needle size?

    1. Hello, Jim

      I used Top Gun fabric for this project instead of the Sunbrella that I’ve used on everything else. I want to see how it compares and holds up. I used V-69 White Polyester thread. I don’t remember what size the needle is but I think it’s the next to largest size that will fit my machine. I use the largest for V-92 thread but my machine struggles with that large of thread.

      Hope that helps,

  2. Jib Sock Drawing link is not downloading

    1. Thanks for the heads-up, Joanne. The link is working now.


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