Boatworks

Making a Mainsail

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Staring at the heap of boxes that had just arrived from Sailrite, I kept asking myself one question: What on Earth made me think I could build my own mainsail?

I’d decided to build my own mainsail from a kit for the experience and to save money, both laudable goals. But the truth was, other than once repairing a genoa under the supervision of an experienced sailmaker, I had no experience sewing. None.

Taking a deep breath, I opened the boxes from Sailrite and laid out their contents—an LSZ-1 zig-zag sewing machine and assorted accessories, sailcloth, various sailmaking tools—even batten material. Yup, I now had everything I needed to make a complete idiot of myself.

The instructions, however, were carefully written so that even a bumbling neophyte (like me) could understand them. Every step was clearly and concisely documented, along with diagrams and photos where required. My confidence began to grow—perhaps, just maybe, I could do this.

The key to successful sailmaking is having the right equipment for the jobSailrite not only explains how to do things, but also why they are done in a certain way, which makes it that much easier to understand each stage of the process. The explanations also serve to dissuade you from making experiments that might cause trouble later. For example, I missed a sentence regarding the patches for the small reefing grommets, and found that I created quite a bit more work for myself as a result. Follow the instructions exactly, and you will be fine. Should you still have questions, the Sailrite staff is available by phone or online to advise you.

 

 

 

Normally, the first step when building a sail is measuring for it. However, that wasn’t necessary with this sail, as the measurements for most production boats’ sails are in Sailrite’s database. They did ask me to confirm my boom length, just to be safe, in case the boom had been changed over the years: an attention to detail that was typical of my dealings with the company.

In my case, the first step was to lay out the sail panels, which had been precut and marked for assembly on a flat-bed plotter. All of the relevant lines—seam line, leech, foot and hem—are clearly marked and identified. It’s actually very hard to go wrong. If you can assemble a simple jigsaw puzzle, you can do this. As promised, the fit was perfect, and nothing caused me to wonder if I’d made a mistake. My confidence grew still more.

The author hard at work, stitching together the panels of his new mainsailIt’s good to have a large workspace for this kind of project, and I was fortunate in that Jeff, owner of Coastal Kitchen at Morningstar Marina in St. Simon’s, Georgia, made his banquet hall available to me. This kind of project is always easier if you have more room. I know others have built sails in much less space, but it makes it a lot more challenging.

Time spent reading and rereading the instructions helps immensely while you’re on your knees with scissors, tape, etc., in hand. Request the PDF version of the instructions. It has color photos, which help clarify the work even more.

 

Carefully following the instructions, I joined the sections together with double-sided basting tape, making “subsections” that I would eventually sew together. It was very satisfying to see the sail begin to take shape, but I wasn’t fooling myself. I still had to sew these pieces together.

Sailmaking can get difficult if you use a sewing machine that isn’t heavy enough to handle the material. However, the Sailrite machine is designed to power through multiple, heavy layers of sailcloth—as many as seven or eight at a time. Out of curiosity, I tried to sew some heavy stuff with a good-quality household machine, and the going was hopelessly slow. I would never attempt this kind of a project with anything less than a machine specifically designed to do heavy work.

If you have no prior sewing experience, I strongly recommend you attempt a smaller project first. The skills aren’t difficult to learn, but they do require some practice: the ability to sew ruler-straight stitching for 45 feet along a one-inch seam is not a talent mankind acquired through evolution.

It also helps to have an assistant, especially as your sail gets bigger and the amount of cloth gets more difficult to handle. Work slowly. As your skills improve, you’ll find speed comes naturally. When I started, two or three feet of stitching was a challenge. By the end of the project, I was comfortably sewing seams the length of the leech, a distance of nearly 45 feet. Triple stitched. Singlehanded. And uphill both ways!

Once the sections are sewn, the next step is to sew in the patch assemblies, the thick sections of cloth that support the reef points, head, tack and clew. Once again, explicit instructions and the marked, precut sailcloth pieces make things easy. Glued to the sail, the patches must be sewed to one another and to the sail. Again, this becomes progressively more challenging as the sail bulks up and requires assistance.

Stitching the slides onto the  sail was one of the most time-consuming parts of the projectAfter that comes the sail’s edge treatment. This is where things can become a bit tricky. You have to be careful, for example, not to sew over the batten pockets you’ve built, or the boltrope and the leech line. Again, it’s not difficult. You just have to be sure to slow down and focus on what you are doing. As it was, I found myself pulling out stitches to correct errors here and there.

If you choose to install intermediate reefing points (which you should if you are considering any kind of serious cruising), this will add yet more complexity to sewing the leech. If you ever feel unsure about what you are doing, read the instructions again—preferably before you start that next step.

After that comes the last step: detailing. Most of your sewing is now done, machine sewing, that is. To install the corner grommets, the headboard, reef grommets and any other hardware not yet dealt with, you’ll be working with a hammer and die sets, big hand needles and a sailmaker’s palm. I discovered, this part of the project was physically the hardest and most time-consuming: sewing all those slugs onto the luff seemed to take forever.

Eventually, though, it was time for the very last job of all: applying the Sailrite logo. Ironically, it’s a peel and stick patch—no sewing required.

I confess, I bent on my new sail with some trepidation. If I’d made any serious mistakes, particularly in sewing in the boltrope, they were about to become obvious.

Up the mast she went, though, and...yes, everything looked good. No obvious errors in shape or fit! I was equally nervous as I adjusted the outhaul and other control lines. I had a lot of time and effort and ego invested in this project. But everthing appeared to be as I’d hoped.

Two weeks later I headed north out of St. Simons and on to the Atlantic. In 10-15 knot winds, the main filled out and—well, the day was a 7-knot romp up the coast. In my opinion, it performed at least as well as my previous professionally built mainsail, so that both my wallet and my ego couldn’t have been happier.

Since then I’ve been asked if I’d ever build another sail. For many, the effort won’t be worth the savings—about 50 percent less than you pay to have Sailrite build the sail for you (which is an option). But the feeling of pride you get sailing with a sail you’ve built yourself is a huge bonus.

I didn’t keep track, but I estimate this project took a good 50 hours. I didn’t rush it at all, and if I was unsure of anything, I took the time to double check before going to work with my needle and thread. If I’d been more experienced in sewing, I’m sure it would have taken much less time. You should also have a helper throughout the project, as some parts of the job are very difficult to do on your own.

One thing I’ve learned: I’ll never again back away from maintaining or repairing my sails. The knowledge I’ve gained on sail construction from this project was invaluable in that regard. And that’s good—I’ve noticed the leech of my genoa needs some attention.  

More on sail repair:

  • Rudy and Jill Sechez's Hand–Tailored Sail Repair HERE
  • Mark Corke's Essentials for DIY Sail Repair HERE
  • Peter Nielsen's Left- and Right-Handed Palm Cruising Tip Here 

 

Wally Moran spends
much of his sailing life on the
Intracoastal Waterway

 


 

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