CHAPTER 1

Introduction to Splicing

Rope in use is attached to something else—to another rope, to an object tobe moved or prevented from moving, or to an object that prevents the rope frommoving. The attachment can be accomplished with a knot, but knots are bulky and,by their nature, cut the breaking strength of the rope in half. The alternativeis a splice, which is capable of attaining a rope's full strength.

Splicing teaches you not only about the splice itself, but also about theconstruction and quality of the raw material. The knowledge gained frompracticing the splices in this handbook should enable you to splice anygeneral-purpose rope. But remember the wise advice, as true today as it ever hasbeen: "Measure twice, cut once."

No single splicing technique can work on all rope because the constructions varyconsiderably. Rope designers, who are functional artists much like architects,seek a perfect construction using the characteristics of various fibers:strengths, abrasion resistance, weight, shrinkage, and elasticity. They mustconsider resistance to heat, cold, sunlight, chemicals, water, dye, andmicroorganisms, as well as construction possibilities such as braiding,twisting, knitting, plaiting, wrapping, and gluing.

ROPE CONSTRUCTION

Egyptians on the Mediterranean worked with twisted and braided ropes 3,000 yearsago, as did seamen 12,000 miles away in Asia. Their ropes, knots, and spliceswere much like those we use today, except that ropes of strong synthetic fibershave all but replaced plant fibers over the past few decades. With increasedinternational shipping, ropes from all over the world are now evident in largecommercial harbors.

Any rope is a bundle of textile fibers combined in a usable form. For example, a½-inch-diameter (12 mm) nylon rope might have 90,000 tiny fibers, each witha tensile strength of 2 ounces (56.7 g), giving it a potential breaking strengthof 11,000 pounds (4,950 kg) if the fibers could be pulled in such a way thateach achieved its maximum strength. The 90,000 fibers can be bonded, twisted(laid), or braided, or these construction techniques can be combined in onerope. Regardless of the construction, the actual breaking strength of thefinished rope will be less than the potential strength of its aggregate fibersdue to a shearing action on the twisted fibers when the rope is loaded. Thiseffect is most extreme in laid rope: the U.S. standard for ½-inch (12 mm)three-strand nylon rope, for example, is a breaking strength of 5,800 pounds(2,610 kg); for ½-inch nylon double-braid, it's 15 percent higher.

The old standby, three-strand twisted nylon rope, is the most economical ropeavailable today, at about half the cost of double-braided nylon. It consists offibers (often nylon, but sometimes polyester or polypropylene) spun into yarns,which are then formed into the strands. Nylon three-strand is commonly used foranchor rodes and mooring and docking lines—applications where itsstrength, pronounced stretchiness, resistance to chafe, and reasonable cost areall appreciated.

Double-braid rope came into use with the discovery that careful design andconstruction could induce a braided core to share a load equally with itsbraided cover. When you work with this rope, you must preserve the originalcoat-to-core spatial relationship to retain its inherent strength, so tie theSlip Knot—called for in the splice directions for thisconstruction—both properly and tightly.

Dacron double-braid is stronger than three-strand twisted nylon rope (or three-strandor single-braid Dacron, for that matter), but it is also nearly doublethe price for ½-inch (12 mm) rope, and the difference in cost should beconsidered against the line's intended use. (Dacron is a DuPont trade name forpolyester, and the two terms are often used interchangeably.) Whenever thebreaking strength of a rope is critical, the manufacturer's specificationsshould be consulted. Some low-cost rope on the market is made to look likedouble-braid, but it is not, so check the product carefully and deal withreputable suppliers.

Polyester double-braid rope is low-stretch and resists kinking and hockling; ithandles well and is good for halyards and sheets.

Single-braid (also known as solid-braid) polyester is more supple, lessexpensive, stretchier, and somewhat less strong and durable than double-braid.It's useful for multipart mainsheets or vangs where ease of handling is prizedand minimizing stretch matters less than it does for, say, jibsheets.

Braid with three-strand core is another common rope for running rigging onyachts. As its name implies, the outer cover is braided, in this case with 16plaits or braids. The core, a three-strand twist, carries most of the strength.Often called Marlow, for its English manufacturer (Marlow Ropes, Ltd.), it issold with standard and fuzzy covers, the latter being soft on the hands andholding knots well. The covers are available in colors—a convenience when,for example, one must find a halyard quickly in a maze of running rigging.Marlow can be difficult to find in some areas.

Dacron braid with a Dacron parallel-fiber core is another rope with most of thestrength in the core. It stretches much less than double-braid and, pound forpound, it is as strong as stainless steel wire (see Wire Halyard ReplacementChart), so there is a trend toward using it to replace wire on recreationalnonracing sailboats. In the United States, Sta-Set X (New England Ropes) is apopular brand. This rope is also stiff and a poor choice where bend and flex...