Use V-69 and a #16 or #18 needle for fabrics up to six ounces and with Sunbrella. Note: when sewing on an Ultrafeed sewing machine with V-69 thread, a size No. 20 needle works best.

Thread quantity: 1 oz V-69 (350 yards per spool)

Sailmaker's thread needs to be pulled up off the top of the tube. This puts an extra twist in the thread which contributes to its strength and helps to keep the thread from unlaying. It also enables a smooth feed off the top of the cone which eases tension problems.

Which Thread or Needle Do I Use?

Thread	Needle	Fabric Weight
V-30	#12 or #14	Fabrics under 1 1/2 ounces
V-46	#14 or #16	Fabrics under 3 ounces
V-69	#16 or #18	Fabrics up to 6 ounces (can use for Sunbrella)
V-92	#18 or #20	Fabrics up to 10 ounces (can use for Sunbrella)
V-138	#20 or #22	Fabrics over 10 ounces. This thread is too heavy for practical use in home sewing machines.

Not all Polyester Threads are Equal

Sailmaker's primarily use polyester fiber threads. They are extremely strong and durable in outdoor applications and are dimensionally quite stable, i.e., they will not shrink or stretch enough to create problems. But it is not enough to simply specify a polyester thread.

As is often the case with synthetic fibers, the manufacturing process permits a widely variable thread type. The fibers can be produced with a "spun" or fuzzy surface or with a very smooth surface. The spun fiber is used in the construction of thread for dressmaking because it sews better—the fuzzy surface tends to pull through tension devices in a more consistent way than a hard, smooth, and rather brittle polyester does. But this spun thread is not nearly as strong as the smooth type. As a result, its use is rightly limited to dresses, kites, and the like.

There are two main categories of "smooth" polyester fiber thread: soft finished and bonded finished. The bonded version is especially treated to protect it from heat buildup and to improve its sewability—a coating is added that makes the thread slide more easily over metal parts. This bonding makes stitch tension more controllable.

Cheaper polyester thread, even the bonded variety, does not have the same sewability as that which is more expensive especially in home sewing machines. We have tried many thread companies in the past 26 years. One brand stands out above the others—Heminway and Bartlett manufactured by the Barbour Co (Now Coats Thread). Their bonded Dabond (polyester) thread has set an industry standard because of its high strength and controlled stretch, its stability in sunlight (UVR) and its resistance to needle heat, abrasion, saltwater and mildew. It will very seldom fray at the needle eye, and its bonded finish is so consistent that machine tension does not have to be continually adjusted.

As a rule, you will use about 10 yards of thread for each yard of sailcloth in zigzag mode. This provides some extra for sewing errors.
 

Thread Size	Government Size	Textile Size	Avg. Tensile Strength Lbs.
V-30	AA		4.7
V-46	B	45	7.4
V-69	E	70	10.9
V-92	F	90	14.5
V-138	FF	135	22.6