Repair a Sailboat Sail Using a Tent Rain Fly.

I acquired an old Super Snark Sailboat that had a dirty, dry rotted sail and decent hull. Most of the holes in the sail were small, but there were some long tears as well. The first thing I tried, of course, was to apply a bunch of duct tape to make sure the boat would float.

It sailed quite well, but as the wind picked up the sail began to fail repeatedly. We made it back to shore and I knew I had to put a new sail on it quickly to get back out on the water again. Almost immediately I knew what I was going to use: a disappointing old tent fly we had in our basement...

Last year my wife had returned from a garage sale gleaming because she bought a six person tent for only $2.00. When I opened it up, we were disappointed to learn that the lousy seller had failed to included the tent in the deal and so all we had were the poles, stakes and rain fly.

It sat in a basement corner for a year until I pulled it out with lofty plans of sending it out to sea (or tiny lake).

Step 1: Step 1: Salvage the Sprit Sleeves

If you're trying a similar repair on a Snark, Super Snark, Sunfish, or similar sailboat with a lateen sail, be sure to salvage the sprit sleeves. Many small sailboats use this sail system because its so easy to rig and sail.

These sails are made of lighter nylon or polyester fabric, but the sprit sleeves on the luff and foot edge are usually much heavier fabric. The sprits are the two poles that form the shape of the lateen structure and by salvaging the sprit sleeves will also save a lot of sewing.

To salvage the sleeves, cut along the sewn edge, being sure not to damage the sleeves. If at all possible, try to leave any grommets attached to the sprit. My salvaged sprit sleeve was L shaped with a grommet in each corner with small triangular piece of fabric around each grommet.

Next, lay the old sail on top of the tent fly and position it so that they sail fits and aligns with as few seams as possible in the sail area. You'll see in the pictures on Step 3 that I managed to only have two
rain fly seams in my sail and one of them is perpendicular to the leech. The rain fly seams should be taped and sewn well, but too many may affect the sails performance.

I actually thought the rain fly would make a good sail because it is water proof and so wind proof, but the dome shape of the rain fly would also lend itself well to forming the air foil shape necessary to sail upwind.

If you don't have a good donor rain fly, you can substitute water resistant fabric.

Step 2: Step 2: Cut Out the Sail and Begin Sewing

Cut out the sail
You may notice the old sail has a slight curve to the two edges where you just removed the sprit sleeves. When you begin cutting, make sure you are not cutting in a straight line, but follow the curve instead. The curve in the luff and foot edge will force the extra fabric into the sail area which help give the sail shape.

Also, be sure to leave a seam allowance on all edges. If you salvaged the sprit sleeves, you wont need much extra fabric as a seam allowance, maybe 1" inch on all sides. As you begin sewing, you'll use the seam allowance to sew a rolled hem for strength.

If you did not keep the sprit sleeves, be sure to leave enough fabric to form the sleeves into which the each sprit slides, unless you have another method to attach the sail to the sprits.

Begin Sewing
As I mentioned earlier, you'll use a rolled hem for strength. What this means, is you take the frayed outer edge of the fabric and roll, or fold, it over itself so that the frayed edge is sewn under the stitching. It may be difficult at first, but you'll get the hang of it. It helps to fold the frayed edge over and then to fold the folded edge over so the frayed edge disappears inside the fold. Place the sewing machine foot down on the start of the hem and then maintain the fold or roll as you sew the edge.

Now, before you begin sewing, set your sewing machine to sew a stitched zig zag pattern, so each zig zag has several stiches in each zig and zag instead of loose thread. Sew from either of the tips of the sail toward the tack, or bottom corner of the sail. This stitch is strong, but also lets the sail stretch a little.

Pro Tip
If you're using a large spool of thread, as I did, try putting the spool on the floor instead of a spool carriage. I had issues with thread tension until I put the spool on the floor. If you're using small spools, ignore this tip as a small spool on the floor would be silly. Also, I sew on my kids craft table. The low height helps when you're moving a lot of fabric around.

Step 3: Step 3: Finish Sewing and Enjoy

I sewed both tips first and worked my way to the bottom corner, resulting in a bunch of unsightly fabric that I pleated toward the center of the sail. Be sure to sew from one tip toward and around the bottom corner and back to the other tip to sew any access fabric out of the sail.

Now that you have the entire perimeter sewn, you'll need to go back and reinforce the head, tack and clew. This means, go back and reinforce each corner. I was able to leave the grommets attached to the sprit sleeves, so I simply went back and sewed around those grommets. These parts of the sail take a lot of the vertical and horizontal force of the sail and you want to make sure they don't tear.

If you can't sew around the salvaged grommets, you can cut a triangular shape of discarded rain fly fabric to reinforce each corner. You can then add your own grommets or method of securing the sail to the spits by sewing a button hole or fabric loop into these corners.

Be sure you have a paddle in the boat in the event your sewing fails or you don't have good upwind performance. If it works, you might be the only Kelty, MSR, or Coleman sail on the waters.

Happy sailing.