Tips for Sewing Large or Heavy Sails on the Ultrafeed LSZ

Even though the Ultrafeed^® LSZ Walking Foot Sewing Machine is small and compact, it still has the power to sew larger sails for boats up to 35 feet. If you’re thinking about taking on a large sail project like this with your Ultrafeed, we have a few pointers and tips to help make your sail construction or repair as smooth and successful as possible.

When working on a large sail project, the preparation you do in advance of sewing is key to how smoothly your project will go. First, you’ll want to make sure you have a large enough workspace so the sail can be supported as you sew. If the sail gets caught on something, falls off the front of your table, or drags behind the sewing machine, you could see uneven stitch spacing, skipped stitches or you could even break a needle.

Timing & Tensioning Your Machine

Before beginning any large or heavy project, such as a sail, it's helpful to verify your machine's timing. Verifying proper timing will ensure your needle is aligned and your machine won't skip any stitches. Always check the machine's timing with a #20 needle installed, no matter what size needle you'll be sewing with. This is also a great time to clean out your hook and make sure it's free of any lint or dust. If you need guidance on how to check your machine's timing, refer to your Ultrafeed Guidebook, which has a thorough and extremely helpful section on machine timing and maintenance.

With your thread and needle installed and ready to go, get a scrap piece of two layers of Dacron^® and set the tension in those two layers. You want a tension where the knot is pulled into the sailcloth weave. This will be a higher tension setting than is used when sewing canvas. Once you have the tension properly set in two layers of fabric, it should regulate itself as you sew your project, but it’s always a good idea to double-check the tension at the end of each line of sewing.

Needle & Thread Recommendations

Make sure you use appropriate needles and thread for the application. We recommend using Tex 90 polyester thread for most large sails. For 6.4-10.4 oz., start with a #20 needle; this will be sufficient for sewing two to three layers, such as seams or patches. If your material is over 7.4 oz., we suggest switching to a #21 Serv7 for seaming or a #22 SD1 needle for sewing thicker corner patches. If you're starting with anything over 10.4 oz. of sailcloth, start with a larger needle. These thick needles are great for use with heavy sailcloth because they have a cutting point that partially cuts into the fabric and then pushes the fibers away, leaving a clear path for the thread without breaking or fraying. This should be avoided in the seams but has no measurable effect on corner reinforcement.

Tips for Assembly

When you’re all ready to sew, you’ll want to consider how best to feed the bulk of your fabric through the sewing machine. If you’re building a new construction sail, piece it together so the sail builds out and away from the sewing machine as you sew. If it’s a sail repair, you’ll want to roll up the sail on both sides and then feed one of the rolls carefully underneath the arm of the machine.

If you’re assembling a new sail, it’s also a good idea to be careful with the placement of basting tape as you baste pieces together. Always make sure that the overlapping fabric is thoroughly covering all of the basting tape, as it will catch dirt if left exposed. We suggest using the Sailrite^® Leather Press Roller (#123301) or a wallpaper seam roller to press the basted seams together. This will help them hold while you sew.

Tips for Sewing

When you start sewing, it’s important to find a consistent rhythm with your sewing speed. No need to be fast, slow and steady is perfect. Another helpful tip that you might want to consider is to change to a full bobbin with the start of each long row of sewing. We like to do this so you always know how much is in your bobbin and then you won’t have an awkward start and stop point in the middle of your sail. You can then use the partial bobbins for the corners and other smaller areas.

When it’s time to attach the boltrope, you’ll need to have a left roping zipper foot. This will let you get your stitches as close as possible to the boltrope to sew what’s called the “sticking stitch” that pushes the boltrope tightly against the fold in the tape. When you’re ready to sew this stitch, set your machine to the longest straight stitch and the needle to the right-hand position.

More Helpful Tips

Here are two more bonus tips for your large sail project. First, we recommend having a hotknife on hand for your project. When you use polyester thread, the hotknife will heat seal the stitching too as you cut pieces to size.

Second, we highly recommend spending a little extra to get good webbing. A high-quality webbing like Dyneema^® will provide all the needed strength with less bulk than cheaper options. The thinner webbing will be much easier for your Ultrafeed to sew as well. Think of it as choosing the right material for your machine.

We should also note that if your sail calls for 7.4-ounce Dacron or heavier and there are places on the sail that will have 8 layers of Dacron and webbing, then you will be hitting the upper limits of what the Ultrafeed can handle. If you’re right at this point, you may be able to use the hand crank on the Monster^® II Balance Wheel to get through the heaviest corners of the sail, so making sure you have the Monster II is a must. Alternatively, you can upgrade to the Sailrite^® WorkerB^® Power Pack to power through all your sail's layers of fabric and webbing. The 1/4-horsepower motor and power boosting technology provide enough torque to push through such thick and heavy assemblies. With the Monster II wheel, the WorkerB offers extreme slow speed sewing.

Do you have experience sewing large sails on your Ultrafeed LSZ Walking Foot Sewing Machine and have any tips or advice to add? Join in the discussion in the comments below!