A permanent method of joining two lines together, or one line to itself, is splicing. Not only is a splice the least likely to part, it also retains the greatest amount of strength, in some cases up to 95%.
Each line is opened up, placed together (called “crotching”) and secured (by tape or whipping, called “stopping”), and then tucks are made. This holds about 85% of the breaking strength of the line, and so is the best splice for repairing parted mooring line until it can be condemned and replaced. Interestingly, the only short splice acceptable for cargo use is with wire rope, not with synthetic or natural materials.
There are many forms of long splices, resulting in the addage, “different ship, different long splice.” More time consuming than a short splice to effect. Strands from each line replace strands of the other line for some length. This keeps the splice the same diameter as the two lines being spliced and is useful for running rigging which passes through small openings, blocks, and pulleys. The cost is strength; it will hold about 80% of the original breaking strength of the line.
A permanent loop may be affixed in line. For greater strength, a steel thimble may be spliced in which holds the line in a fixed shape, reduces chafe, and extends life.
For wire rope, the strands should be unlaid a distance of 36 times the diameter of the wire in inches in preparation for splicing. After completing, the splice should be parceled and served to prevent hand injury by covering the loose ends, covering any “fish hooks” or “meat hooks” as these stray wires are called.
Wire splices require the use of a wire vice—called a rigger’s screw—a marlingspike, a metal thimble, and a sturdy pair of leather gloves. The thimble is captured by the wire during the splice and takes the chafe of future loads, adding to the strength of the finished product.
A Liverpool splice uses backhanded tucks, that is, the tucks go with the lay of the wire. This is not a good splice for any form of running rigging or cargo operations. If the eye is twisted the strands may open, causing the splice to fail.
A splice acceptable for cargo use is not unlike one made in natural or synthetic rope. This involves three tucks with whole strands and two tucks with ½ the wire cut from the tucking strands. It is permissible to use this splice for cargo work.
An old technique not likely to be observed, but still technically correct, is called serving. This is the process of covering wire rope (or manila or hemp) standing rigging with a protective layer of smaller stranded tarred manila, known as marline. This would then in turn be slushed with pitch tar to form a weatherproof seal. A serving mallet, a specially designed tool, would be used to apply the service.
This or some other covering (such as leather) should be applied to a wire splice that may be handled, on account of the fish hooks, or meat hooks, of stray pieces of wire that may otherwise snag working hands.